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Annual Research and Monitoring Report, 2007 Lewa Wildlife Conservancy

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Lewa Wildlife Conservancy

Research and Monitoring Annual Report 2007

Geoffrey Chege and Edwin Kisio

February 2008


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ACKNOWLEDGEMENTS The staff of the Lewa Research and Monitoring Department would like to thank the following individuals and institutions for their unwavering moral, logistical and financial support of activities completed in 2007: The Board of Lewa in Kenya, USA, UK and Canada, Dr Tim Woodfine, Tanya Langenhorst and Guy Parker, Grevy’s Zebra Trust, Kenya Wildlife Service, Management of Lewa, Marwell Conservation, Mulhouse Zoo through Pierre Moisson, Mpala Research Centre, Northern Rangelands Trust, Princeton University, Prof Dan Rubenstein, Richard and Rhoda Goldman Fund, Sacramento Zoo, Save The Elephants, Saint Louis Zoo, Safaricom Ltd, Tusk Trust, Toronto Zoo, US Fish and Wildlife Society, Wilhelma zoologisch-botanischer Garten Stuttgart, Zucher Tuitchetz and Zurich Zoo. Finally, special thanks to the security personnel who gather basic wildlife monitoring data in the field together with other staff who offer logistical support to the department. Without all your contributions, the specific details described in this report would not have been completed.


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EXECUTIVE SUMMARY In 2007, the Research Department of Lewa undertook several pertinent research and monitoring activities aimed at providing insight into specific management issues to better inform decisions on proactive management of species and habitats in the Conservancy. Black rhino The population of black rhinos rose to 55 following three births representing 5.7% growth rate compared to the national meta-population target of 5%. The average growth rate since 2000 has been 10%. Mean inter-calving interval was 2.5 years with several calving intervals being <2.0 years. In particular, Mawingo’s last two inter calving intervals were ≤1.6 years. This was exceptional considering that the gestation period of black rhinos is 18 months. Overall, Lewa’s population performance in the year was above average compared against standard benchmarks for evaluating performance of black rhinos. All rhinos either maintained or improved their body condition due to the 2007 rains. Six “clean” rhinos were notched for identification. Introduction of camels into the extreme western side of the former Manyagalo Ranch and increased human activities in the central parts appeared to negatively affect the spatial and temporal utilisation patterns of rhinos in the two areas. The carrying capacity of black rhinos was estimated to be 70. Surplus production will need to be moved out in the next two years. It was recommended that the population of black rhinos on Lewa should be maintained at maximum sustained yield of 52 non-sex biased stock for maximum productivity. Efforts should be enhanced to either extend the existing IL Ngwesi sanctuary and translocate excess animals out of LWC or to amalgamate Lewa and Borana and ultimately with Il Ngwesi in the next five years in order to raise the ecological carrying capacity of the expanded area to about 160 animals and become a Key 1 rated population. Before this happens, there will be need to closely monitor activities of the upcoming adult bulls for remedial actions to be undertaken as necessary. White rhino The population of white rhinos stood at 37 animals. There were two births in the year. Age at first calving was 7.9 years and inter-calving interval was 2.5 years. Seven rhinos have been translocated to Ol Pejeta in the last two years in order to achieve a balanced sex ratio, and establish a founder and breeding stock of the same at OPC. Even though Guidelines on Management of White Rhinos in the country do not advocate rapid growth of this species, it was recommended that the current growth rates in LWC should be maintained in order to attain stocks that can be moved to other private and community areas on custodianship agreement basis. For such rates to be achieved, an active balancing programme should be continuously pursued in order to stock a non-sex biased population. Grevy’s zebra The Grevy’s zebra population stood at 430 compared to 399 in 2006 representing a potential 7% population increase. At least 69 foals were born in the year. Survival rate of these foals at the close of the year was 70%. However, this rate was expected to further reduce as monthly foal patrols continued in 2008. The overall recruitment rate into juveniles’ stage of foals born in 2006 was 49% which compared well with 2005 when 47% of foals were recruited. However, the survival rate of foals born on Lewa since 2004 has been below 50% which is the minimum infant survival per annum required for Lewa’s Grevy’s zebra to increase in numbers. Scat analysis of lions showed that zebras continued to form the main diet of lions with twice as much Plains zebra being predated compared to Grevy’s zebra. This contrasted with 2003-2005 when the two zebras were predated almost equally. This lowered rate of predation may have been due to a reduction in lion numbers arising from emigration. This demonstrates the potential benefits that Grevy’s zebra population can achieve when low numbers of lions are maintained in the Conservancy.


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Consequently, it was recommended that in collaboration with Kenya Wildlife Service, lions in Lewa should be maintained at agreeable low thresholds to avoid negative predator-Grevy’s zebra interactions. Such site specific plans have already been incorporated in the National Grevy’s Zebra Strategy Plan, 2007 and have been proposed for inclusion in the National Lion and Hyena Strategy Plan (in preparation). General Wildlife Monitoring The annual game count showed that most of the key wildlife species registered an increment in numbers when compared to the 2006 count. In particular, eland, oryx, Grevy’s zebra, Plains zebra, giraffe and ostrich registered positive trends while waterbuck had a negative trend. Rainfall Lewa received 620 mm of rainfall in 2007 compared to 758 mm in 2006. This contrasted with 286 mm that was received in 2005. This amount of rainfall was also way above the long term mean rainfall of 517 mm averaged since 1972. Management issues A number of issues that have a direct impact on the current status of LWC’s biodiversity were evaluated. Intensive community cattle grazing was found to have a positive impact in improving the range for Grevy’s zebra. In order to achieve extensive optimal results and suit LWC’s ecological and environment conditions, it was recommended that at least 4 bunches of community cattle with a minimum of 500 herds per bunch, should be grazed and paddocked in the Conservancy. In future, both cattle grazing and prescribed burning should compliment each other for extensive results to be achieved. The ecological impacts arising from the annual marathon were similarly evaluated. The significant impacts were categorised into four: depletion of resources; pollution; vegetation degradation; disruption of animal behaviour; and physical impacts. Large stands of Datura stramonium were found to prevent growth of grass and herbaceous material in the heavily infested areas. The plant was insignificantly utilised by browsers. It was recommended that the existing early detection and monitoring programmes of invasive species be maintained. Similarly, regular surveys of known infestation areas should be initiated by laying of transects to monitor the rate of spread or reduction. Again, elimination of D. stramonium should be effected before the fruiting stage.


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TABLE OF CONTENTS

ACKNOWLEDGEMENTS .............................................................................................................. i

EXECUTIVE SUMMARY .............................................................................................................. ii

TABLE OF CONTENTS ............................................................................................................... iv

LIST OF FIGURES....................................................................................................................... vi

LIST OF TABLES.........................................................................................................................vii

1. RHINO MONITORING .......................................................................................................... 1

1.1. Status and performance of black rhinos in Lewa as at December 2007 ....................... 1

1.2. Population growth rate in 2007 ..................................................................................... 2

1.3. Ecological carrying capacity of rhinos on LWC............................................................. 3

1.4. Predicted future rhino growth rates and numbers in LWC ............................................ 5

1.5. Projected future expansion programmes for the benefit of rhinos................................. 6

1.6. Population performance indicators ............................................................................... 7

1.7. Milestones in LWC’s rhino conservation efforts ............................................................ 7

1.8. Home ranges of black rhinos ........................................................................................ 8

1.8.1. Breeding female black rhinos ............................................................................... 8

1.8.2. Breeding males black rhinos................................................................................. 9

1.9. Translocation .............................................................................................................. 12

1.10. Ear notching of black rhinos ................................................................................... 12

1.11. Recommendations.................................................................................................. 12

1.12. Rhino body condition scores................................................................................... 12

1.13. Performance of white rhino in Lewa........................................................................ 13

1.13.1. Status of white rhinos in LWC, 2007............................................................... 13

1.13.2. Growth rate in 2007 ........................................................................................ 14

1.13.3. Sex ratio and translocation ............................................................................. 15

1.13.4. Overall performance of white rhino on LWC................................................... 15

2. GREVY’S ZEBRA RESEARCH AND MONITORING.......................................................... 16

2.1. Introduction ................................................................................................................. 16

2.2. Methods...................................................................................................................... 17

2.3. Results and discussion ............................................................................................... 17

2.3.1. Dynamics of Grevy’s zebra numbers in 2007 ..................................................... 17

2.3.2. Survival and recruitment rates of foals born in 2006........................................... 18

2.3.3. Survival and recruitment rates of foals born in 2007........................................... 18

2.4. Seasonality of foaling.................................................................................................. 19

2.5. Inter-foaling interval .................................................................................................... 20

2.6. Distribution of lactating females and foals in 2007...................................................... 21


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3. PREDATOR MONITORING IN LEWA ................................................................................ 23

3.1. Lion profile on LWC as at 2007................................................................................... 23

3.2. Collaring, tracking and identification of lions............................................................... 23

3.3. Collection of scat ........................................................................................................ 23

3.4. Scat and hair analysis................................................................................................. 24

3.5. Results and discussion ............................................................................................... 24

3.5.1. Dynamics of lion population in Lewa .................................................................. 24

3.5.2. Scat and hair analysis in 2007............................................................................ 25

3.6. Comparative assessment of predation rates, 2004-2007 ........................................... 26

3.7. Conclusion .................................................................................................................. 26

4. TRACKING OF COLLARED GREVY’S ZEBRA IN NORTHERN KENYA........................... 27

5. GENERAL WILDLIFE MONITORING ................................................................................. 30

5.1. Annual game census .................................................................................................. 30

6. ECOLOGICAL MONITORING ............................................................................................ 33

6.1. Rainfall in 2007 ........................................................................................................... 33

6.2. Vegetation monitoring................................................................................................. 34

6.2.1. Grass assessment.............................................................................................. 34

6.2.2. Prescribed burning ............................................................................................. 34

6.2.3. Fixed point photography ..................................................................................... 34

7. MANAGEMENT ISSUES .................................................................................................... 35

7.1. Improvement of rangeland for Grevy’s zebra.............................................................. 35

7.1.1. Background ........................................................................................................ 35

7.1.2. Methods.............................................................................................................. 36

7.1.3. Results and discussion....................................................................................... 37

7.1.4. Impact of the programme and future .................................................................. 38

7.1.5. Recommendations.............................................................................................. 38

7.2. Management of invasive species................................................................................ 39

7.2.1. Invasive and alien species in LWC ..................................................................... 39

7.2.2. Control of invasive species in LWC .................................................................... 40

7.3. Impact of the Marathon............................................................................................... 42

7.3.1. Depletion of natural resources............................................................................ 42

7.3.2. Disturbance to biodiversity.................................................................................. 42

7.3.3. Pollution.............................................................................................................. 43

7.3.4. Physical impacts................................................................................................. 43

7.3.5. Compromise in wildlife monitoring activities: ...................................................... 43

8. REFERENCES ................................................................................................................... 45

9. APPENDIX 1: BREEDING PERFORMANCE OF RHINOS ON LEWA, 1985 - 2007 .......... 46


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LIST OF FIGURES

Figure 1.1: Sex and age structure of black rhinos in Lewa, December 2007 ................................ 1

Figure 1.2: Number of calves born per breeding female black rhino in Lewa: 1984-2007............. 2

Figure 1.3: Trend in black rhino population including births, deaths, translocations and temporal

growth rates on LWC, 2000-2007 ................................................................................................. 3

Figure 1.4: A hypothetical production curve of rhinos showing density dependent declines in

performance beyond 75% of ECC with zero growth rates at ECC level........................................ 4

Figure 1.5: The relationship between the current population, predicted ecological carrying

capacity and maximum sustained yield, and surplus production that need to be regularly

removed to maintain maximum growth rates of rhinos on LWC, 2007.......................................... 5

Figure 1.6: Predicted performance of black rhinos on LWC at 6% and 9.4% p.a. growth rate...... 5

Figure 1.7: The relationship between MSY, current population and future population numbers on

LWC based on 6% and 9.4% growth rates ................................................................................... 6

Figure 1.8: Location of LWC showing the possible expansion routes to Borana and IL Ngwesi

Group Ranches for subsequent colonisation by black rhino ......................................................... 7

Figure 1.9: The ranging areas of four breeding female black rhinos on LWC, 2007 ..................... 9

Figure 1.10: The ranging areas of five breeding female black rhinos on LWC, Jan-Sept 2007... 10

Figure 1.11: Ranging areas of Mama C and Seiya between Jan. – Sept. & Oct. – Dec. 2007.... 10

Figure 1.12: Ranging areas of Ndito and Nashami between Jan. – Sept. & Oct. – Dec. 2007.... 11

Figure 1.13: Ranging areas of Oboso and Zaria between Jan. – Sept. & Oct. – Dec. 2007 ....... 11

Figure 1.14: The ranging areas of Sonia between Jan. – Sept. & Oct. – Dec. 2007 ................... 12

Figure 1.15: Sex and age structure of white rhinos on LWC, December 2007............................ 14

Figure 1.16: Number of calves born per breeding female white rhino in LWC: 1984-2007 ......... 14

Figure 1.17: Trend in white rhino population including births, deaths, translocations in LWC..... 15

Figure182.1: Grevy’s zebra population trends in Lewa and Kenya’s Rangelands, 1978-2007...... 16

Figure192.2: Comparison of survival rate of Grevy’s zebra foals born on LWC, 2003-2007 ......... 18

Figure202.3: Comparison of Grevy’s zebra foals born annually on Lewa since 2003 ................... 19

Figure212.4: Age of Grevy’s zebra foals born in 2007 and still surviving at end of the year.......... 19

Figure222.5: A comparison of numbers of Grevy’s zebra foals born per month on LWC against the

2007 rainfall – note the non-synchrony of foaling with the rains.................................................. 20

Figure232.6: A comparison of numbers of Grevy’s zebra foals born per month on LWC against the

2006 rainfall – note the non-synchrony of foaling with the rains.................................................. 20

Figure242.7: Proportional inter-birth intervals for Grevy’s zebra on LWC, 2007............................ 21

Figure252.8: Distribution of Grevy’s zebra foals and juveniles on LWC, 2007 .............................. 22

Figure263.1: Performance of Grevy’s zebra and lions in LWC, 1996-2007................................... 24

Figure273.2: Trend in the number of lions on LWC, 2000-2007.................................................... 25


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Figure283.3: A comparison of the proportion of equids versus bovid hair found in lion scat on

LWC, 2004-2007......................................................................................................................... 25

Figure293.4: Comparative assessment of predation rates of Grevy’s and Plains zebra from hairs

found in lion scat ......................................................................................................................... 26

Figure304.1: Movement patterns of 3 collared Grevy’s zebra in Laisamis area, Feb. – Jul. 2007. 28

Figure314.2: Movement patterns of one collared female Grevy’s zebra between food and water in

Laisamis area covering 280 km from 1-14 Mar. 2007 ................................................................. 28

Figure324.3: Movement patterns of Liz (June 2006 – March 2007) showing the extensive

distances travelled by the Grevy’s zebra from the National Reserves to the community areas of

Kalama and West Gate (mapping by Henrik B. Rasmussen)...................................................... 29

Figure335.1: Comparison of the dynamics of some key wildlife species on LWC, 2006-2007 ...... 30

Figure345.2: Trend in Grevy’s and Plains zebra numbers, 1999-2007.......................................... 32

Figure355.3: Trend in Buffalo, Eland and Waterbuck numbers, 1999-2007 .................................. 32

Figure376.1: Monthly rainfall received in LWC (2005-2007) against the long-term mean ............. 33

Figure386.2: Amount of rainfall received per station in LWC, 2007............................................... 33

Figure397.1: Diagrammatic representation of the systematic rotation of cattle pens..................... 37

Figure407.2: A section of the cattle pen showing impact of intense cattle trampling for 5 days .... 37

Figure417.3: A comparison of location of cattle pen sites versus non-pen sites/non-grazed areas

showing the impact of trampling and subsequent phased grass regeneration............................ 38

Figure427.4: Distribution of Datura stramonium on LWC, 2006 – 2007 ........................................ 41

Figure437.5: Areas that witnessed significant wildlife disturbance due to the Marathon ............... 44

LIST OF TABLES

Table 1.1: Sex and age structures of black rhinos in Lewa, December 2007................................ 1

Table 1.2: Inter-calving intervals of female black rhinos in Lewa, December 2007....................... 2

Table 1.3: Performance of LWC’s rhino population against set benchmarks ................................ 8

Table 1.4: Black rhino body condition scores.............................................................................. 13

Table 1.5: Sex and age structures of white rhinos on LWC, December 2007 ............................. 14

Table65.1: Game count figures in Lewa, 2001-2007................................................................... 31

Table 7.1: Exotic plant species found in LWC as at Dec. 2007 (from Giesen et al., 2007) ........ 39

Table87.2: Some pertinent data on the impact of Safaricom Marathon ...................................... 44


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1. RHINO MONITORING

1.1. Status and performance of black rhinos in Lewa as at December 2007 The population of black rhinos in Lewa Wildlife Conservancy (LWC) stood at 55 animals comprising of 16 calves (0≤3 years); 13 sub adults (3≤6 years); and 26 adults (>6 years) (Table 1.1; Figure 1.1). The sex ratio of males to females was 1:1.1. Three births were recorded in 2007 compared to eight in 2006. Seiya (8.7 years) gave birth to her 2nd offspring while Waiwai (12.5 years) and Mawingo (18.6 years) gave birth to their 3rd and 6th calves respectively (Figure 1.2). Mawingo’s last two inter-calving intervals were 18 and 19 months respectively (Table 1.2; Appendix 1). This is significant considering that the gestation period of black rhinos is 16 months. The two inter-calving intervals are the shortest in LWC and may be among the least in the country. Most of the breeding females born in LWC have inter-calving intervals <2.5 years suggesting a settling effect of the rhinos (Table 1.2; Appendix 1). It is predicted that 10 females will calve in 2008 (Figure 1.3). This prediction is based on the mean inter-calving interval of each female and age at first calving of 7.0 years for first time dams. Stumpy (nearing natural attrition age of c.40 years) and Solio are the oldest breeding females in LWC and are expected to calve to their 8th and 9th calves respectively. To date, both Stumpy and Solio have given birth to 7 and 8 calves respectively since they were introduced in LWC in the 1980’s (Figure 1.2). The only other known female to have produced such high number of calves was from Ol Jogi which was credited with 8 calves before she succumbed at c.40 years. Table 1.1: Sex and age structures of black rhinos in Lewa, December 2007

Age class Males Females Not sexed Sub total Proportion in population

Calves (0≤1 year) - 2 1 3 5%

Calves (1<3 years) 8 3 2 13 23.5%

Sub-adults (3<6 years unless calved) 7 6 - 13 23.5%

Adults (6<30 years) 9 15 - 24 44%

Adults (>30 years) - 2 - 2 4%

Grand total 24 28 3 55 100%

02468

10121416

Calves (0≤1 years)

Calves (1<3 years)

Sub adults(3<6 years)

Adults (6-30 years)

Adults (>30 years)

Sub

-tota

l

Males Females Unsexed

Figure 1.1: Sex and age structure of black rhinos in Lewa, December 2007

Proportion of population that is actively breeding


2

0

2

4

6

8

Solio

Stumpy

MawingoZaria

Junip

ierNdit

oNyo

taSonia

Waiwai

MeluayaSeiya

Samia

Oboso

Nashami

Natumi

No.

of c

alve

s/fe

mal

e

Figure 1.2: Number of calves born per breeding female black rhino in Lewa: 1984-2007 Table 1.2: Inter-calving intervals of female black rhinos in Lewa, December 2007

No. Female name Current ageAge at 1st

calving (yrs)1 2 3 4 5 6 7

1 Juniper 19.5 7.6 3.2 2.3 2.2 2.3 - - - 2.52 Mawingo 18.6 ** 2.2 2.8 1.7 1.5 1.6 - - 2.03 Meluaya 11.9 8.4 1.9 - - - - - - 1.94 Ndito 18.0 9.3 3.2 2.2 2.1 - - - - 2.55 Nyota 11.9 7.8 2.7 2.4 1.5 - - - - 2.26 Solio 32.0 ** 3.1 3.5 3.9 3.2 2.1 2.9 2.3 3.07 Sonia 16.4 7.1 4.7 2.4 - - - - - 3.68 Stumpy 39.0 ** ** 3.9 2.8 2.2 3.0 2.0 - 2.89 Waiwai 12.5 6.8 2.1 2.3 - - - - - 2.210 Zaria 19.8 7.8 2.3 2.1 3.0 2.2 - - - 2.411 Seiya 8.7 5.5 2.7 - - - - - - 2.712 Nashami 9.5 7.6 Mean inter-calving interval = 2.513 Natumi 9.3 6.714 Samia 9.3 8.215 Oboso 7.2 5.4

Mean age at 1st calving = 7.3

Inter-calving intervals Mean calving interval/ female

1.2. Population growth rate in 2007 In 2007, the population of black rhinos in LWC had an overall growth rate of 5.7%. This rate was slightly lower than that recorded between 2000-2003 and 2003-2005 (Figure 1.3). However, this lowered rate was expected considering that growth rates in 2005-2006 hit a record high of 15% p.a. with 13 out of the 15 breeding females with calves <2.0 years in 2007. Nevertheless, this rate was above the national metapopulation target of 5%1 as was recommended in the national Black Rhino Strategy Plan, 2000-2005 (KWS, 2000). In 2006, potential factors that may have led to the very high growth rates of black rhinos observed in LWC since 2000, and that exceeds the intrinsic rate of increase (rmax = 9.4%) for non-sex biased rhino populations were discussed2. It was also mentioned that it is critical for LWC and all other rhino areas in Kenya to maintain such high growth rates since large, rapidly

1 Since then, a revised Conservation and Management Strategy Plan for the Black Rhino and Management Guidelines for the White Rhino in Kenya that targets an annual growth rate of 6% in established sanctuaries including LWC, has been produced. 2 Factors needed to achieve high growth rates are contributed by: (i) a non-sex biased population that is expanding as a result of active breeding and has a young age structure; and (ii) when a population as described in (i) is in good habitat.


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breeding and healthy populations not only provide the best insurance against any future poaching events, but also prevents loss of heterozygosity by ensuring maximum rate of gene transfer to future generations (Okita-Ouma, Amin, Adcock, Emslie, Pearce-Kelly and Kock, 2007). It is from this realisation that LWC will need to either translocate its excess stock of rhinos in the next two years or expand into the neighbouring Borana and Il Ngwesi Ranches so as to maintain current productive levels, and for the overall population to attain a Key 1 rating3 as per the AfRSG guidelines (Emslie and Brooks, 1999).

55

29

0

2

4

6

8

10

12

2000 2001 2002 2003 2004 2005 2006 2007 2008Years

No.

of b

irths

/dea

ths/

tra

nslo

catio

ns p

er y

ear

20

30

40

50

60

Pop

ulat

ion

size

No. calves DeathsTranslocations OUT Population size

Predicted biths in 2008

Figure 1.3: Trend in black rhino population including births, deaths, translocations and temporal growth rates on LWC, 2000-2007

1.3. Ecological carrying capacity of rhinos on LWC The ecological carrying capacity (ECC) of black rhinos in LWC was reviewed in 2004-2005 using a multi-faceted model for estimating the holding capacity of rhinos in the nine well-established rhino sanctuaries in Kenya (Okita-Ouma et al., 2007). The model took into account productivity and quality of the standing crop of browse (based on 150 detailed vegetation transects on LWC), and also put into consideration other auxiliary data4 on variables that affect ECC of rhinos. This information was combined with Landsat-7 satellite imagery data to give overall browse-availability and browse suitability index maps for LWC. Using the above parameters, the mean ECC of black rhinos in the Conservancy was adjusted from the initial 83 animals estimated in 2006 to 70 (range 61 to 80) (Okita-Ouma et al., 2007). It is imperative to note that the maximum sustained yield (MSY) for large bodied animals e.g. black rhinos is attained at 75% of ECC, and that exceeding stocks beyond this level is characterised by a tumble in annual growth rates over time as the population under review manifests density dependent declines (Figure 1.4) (Amin et al., 2006). With this in mind, a population that is at MSY has the capacity to produce maximum surplus production that can be translocated without compromising the stock and productivity levels as long as all other factors are held constant. Therefore, in the case of LWC, the MSY of rhinos is 52 (using ballpark figure of 70 = ECC) (Figure 1.5). Hence, with the current population at 55, in theory, MSY has already been exceeded by three animals. Therefore, if the ECC and hence the MSY are correct, then LWC’s

3 A population that is increasing or stable and n > 100 4 Such data include soils, populations of competing browsers, long-term rainfall and temperature.

12%

13% 15% Growth rates for

the period

5.7%


4

population will start showing reduced annual growth rates in the coming years unless remedial actions are undertaken as soon as possible. However, in reality, the estimated ECC will need to be regularly reviewed since:

(i) The dynamics of the numbers of competing browsers is expected to change on a temporal basis and will affect the ECC of rhinos. This is because cumulative browser impacts alter the carrying capacity in the rhino feeding layer, since competitors like elephants remove most of the vegetation lying within 2m (critical feeding level of rhinos) from the ground level. Such a case was observed in Ngulia Rhino Sanctuary (Okita-Ouma et al., 2007) until the elephant population had to be reduced.

(ii) Large, long-lived animals like rhino have the ability to overshoot the ECC for several

years before feedback from the habitat conditions affects population performance indicators (Amin et al., 2006) (growth rate, age at first calving, percentage of females calving per year, proportion of calves in the population, sex ratio etc) e.g. as witnessed in the Solio population5 up and until 2007 when 27 rhinos were translocated out.

It imperative to note that habitat monitoring procedures have already been developed to help provide an additional early warning system in the carrying capacity of rhinos. In line with this, one LWC research staff was trained in the use of such techniques.

0

2

4

6

8

10

0 10 20 30 40 50 60 70 80 90 100

Ecological carrying capacity (%)

Gro

wth

rate

(%)

rmax = 9.4

Density independent phase

Density dependent phase

Figure 1.4: A hypothetical production curve of rhinos showing density dependent declines in performance beyond 75% of ECC with zero growth rates at ECC level (Amin et al., 2006)

5 This population had a disproportionate age structure that was heavily biased towards adults and a skewed sex ratio in favour of males as the population had overshot the carrying capacity and past removes were not based on monitoring data.


5

r max = 9.4%

ECC = 70

75% of ECC ≡ MSY = 52

Current population = 55

Surplus Production that should be removed regularly to attain MSY and maintain growth rates at rmax = 9.4% p.a

Population level

Need regular review due to flactuating biotic and abiotic factors

0

10

5G

row

th ra

te %

Figure 1.5: The relationship between the current population, predicted ecological carrying capacity and maximum sustained yield, and surplus production that need to be regularly removed to maintain maximum growth rates of rhinos on LWC, 2007

1.4. Predicted future rhino growth rates and numbers in LWC The minimum metapopulation growth rate of black rhinos in the well established sanctuaries in Kenya, including LWC has been set at 6% (Okita-Ouma et al., 2007). This rate has been attained in the Conservancy in the past few years where growth rates have even exceeded the intrinsic rate of increase = 9.4% p.a. Similarly, as stated in earlier, the MSY of black rhinos in LWC (c. 52) has already been realised. However, using past performance of this population as a guide (mainly between 2000-2006), and the fact that rhinos can overshoot their carrying capacity for several years before density dependent declines are noted, the time taken to reach ECC of black rhinos in the Conservancy has been modelled using the metapopulation target of 6% p.a. and rmax = 9.4% p.a., assuming all other factors remain constant within the life of the current Black Rhino Strategy Plan in the country. Using the above model, at 9.4% p.a. growth rate, the population will hit the ECC of 70 by 2010 while it will take 1½ years more to reach the same figure at 6% p.a. (Figure 1.6). Using the same projection, the relationship between the current population and estimate of numbers at the close of each year until 2013 is shown in Figure 1.7.

77

55

94

55

40

50

60

70

80

90

100

2007 2008 2009 2010 2011 2012 2013

Years

No.

of b

lack

rhin

o in

Lew

a un

der d

iffer

ent g

row

th ra

tes

p.a.

6% per annum 9.4% per annum

Time to reach ECC at 9.4% p.a. growth rate

Time to reach ECC at 6% p.a. growth rate

Figure 1.6: Predicted performance of black rhinos on LWC at 6% and 9.4% p.a. growth rate


6

ECC = 70

MSY = 52

40

50

60

70

80

90

100

Pop

ulat

ion

of b

lack

rhin

os

in L

ewa

9.4% per annum 55 60 66 72 79 86 94

6% per annum 55 58 62 65 69 73 77

2007 2008 2009 2010 2011 2012 2013

Figure 1.7: The relationship between MSY, current population and future population numbers on LWC based on 6% and 9.4% growth rates

1.5. Projected future expansion programmes for the benefit of rhinos As discussed in section 1.3, the factors affecting the ECC of rhinos in LWC will vary over time due to several external factors. Therefore, for LWC’s black rhino population growth rates and maximum productivity to be sustained in future, there is need to continuously remove surplus production that overshoots the MSY (Figure 1.5). Translocation of surplus animals for long distances may not be economically and ecologically sustainable as few areas in Kenya are available or suitable for the establishment/augmentation of existing stocks. Similarly, the current Black Rhino Strategy Plan lay emphasis on the crucial role that partnership between government, private and communities6 can play in future rhino conservation ventures. Based on this information, the most readily available options for LWC’s rhino expansion programmes would be:

(i) In the medium term, continue to liaise with Il Ngwesi Group Ranch for the expansion of its existing rhino sanctuary and translocate a minimum founder population from LWC into the area. Such plans should follow all relevant KWS guidelines and approvals.

(ii) Amalgamate LWC with Borana Conservancy and Il Ngwesi Group Ranch in the long-term (Figure 1.8). Using experience gained from elsewhere (e.g. Ol Pejeta), a decision should be made on whether to immediately drop the dividing fence lines or to translocate in a phased manner excess animals into Borana, with subsequent dropping of the dividing fence once the two populations have established themselves. As in (i) above, acceptable standards of security and biological monitoring techniques in these areas have to be put in place and verified by all concerned stakeholders. The expanded range including Ngare Ndare Forest Reserve will be approximately 450 km2 with an estimated ECC of about 160 rhinos. If this is achieved, it is predicted that the LWC/Borana/Il Ngwesi stock will be among the first populations to be rated as Key 1 Population in Kenya as described by the AfRSG of the IUCN (Emslie and Brooks, 1999).

6 Community participation has been identified as one of the strategic objectives needed to attain a vision of 2000 black rhinos in the wild as captured in the current Black Rhino Strategic Plan & Management Guidelines for White Rhinos in Kenya (2007).


7

Figure 1.8: Location of LWC showing the possible expansion routes to Borana and IL Ngwesi Group Ranches for subsequent colonisation by black rhino

1.6. Population performance indicators The performance of LWC’s black rhino population was evaluated against standard benchmarks for assessing the level of performance of any rhino population. Overall, LWC’s rhino performance was above average and this was consistent with similar trends observed in the Conservancy since 2000 (Table 1.3). In particular, some rhinos (e.g. Mawingo) have been performing exceptionally well and have registered inter-calving intervals of <1.6 years. Similarly, inter-calving intervals and age at first calving have remarkably reduced in all the females e.g. two females born in LWC calved at 5.5 and 5.4 years respectively (Table 1.2).

1.7. Milestones in LWC’s rhino conservation efforts The total area available to black rhinos has been increased from 5,000 acres in 1984 to the current 62,000 acres that incorporates different land holdings. Within the same time, 61 calves have been born while 9 individuals have been translocated out to establish new populations elsewhere in line with the metapopulation management of rhinos in Kenya. Annual growth rates since 2000 have averaged 10%. Inter-calving intervals have averaged 2.5 years with several females having calving intervals <2.5 years. Age at first calving averages 7.3 years with two females calving at ≤5.5 years. In terms of mortality, only 3 rhinos have been lost since 2000 from causes that can be explained.

Phase 1

Phase 2


8

Table 1.3: Performance of LWC’s rhino population against set benchmarks Benchmark Minimum

recommended Level of LWC’s performance in 2007

Comments for LWC rhino

Growth rate 6% 5.8% Just below average

Inter-Calving Interval 2.5 years 2.5 years Good

% Adult Females Calving/year At least 40% 20% Below average

Age at First Calving <7.0 years 7.3 years Moderate

Sex Ratio Minimum 1M : 1F 1M : 1.2F Good

% of Calves in Population At least 28% 29% Good

Average Mortality Rates Maximum 4% 0 Excellent

1.8. Home ranges of black rhinos

1.8.1. Breeding female black rhinos As in the previous years, the breeding female black rhinos in the Conservancy appeared to have permanently established their homeranges in specific areas of LWC (Figure 1.9 and 1.10). However, in 2007, Ndito, Seiya, Nashami and Mama C appeared to have shifted their core ranging areas from the extreme western edge of the former Manyagalo Ranch when evaluated using a step-wise 50-95% kernel homerange analysis between January – September and October – December 2007 (Figure 1.11 – 1.12). This may have been as a result of entry of camels into the area in September 2007 thus affecting the spatial and temporal distribution patterns of the rhinos. It would be critical to monitor the continued presence of camels in this area for effects on growth of the woody vegetation and utilisation, and further impact on the distribution of rhinos. Zaria, Oboso, Samia and Sonia concentrated their ranging areas in the relatively open Soboiga area (Figure 1.13 – 1.14). These areas are dominated by Aspilia, Hibiscus, Abutilon and Indigofera spp. which form key black rhino diet. Similarly, the core areas of these rhinos appeared to avoid Manyagalo exclusion zone compared to previous years when they used to colonize the area due to its high browse productivity. Avoidance of this exclusion zone may have been as a result of a number of factors including increased human traffic to and from Manyagalo community. Similarly, the area has witnessed infrastructural development in the last one year probably leading to more effects on the spatial and temporal distribution of rhinos. BB (4.2 years) shifted her home range to the eastern side of the Conservancy from Soboiga. This behaviour was previously observed in other sub adult rhinos (Tana, Lacky, Nashami and Maxxine) probably in search of ideal calving grounds and territories. Meluaya and Waiwai remained in the northern areas of the Conservancy which forms rocky and hilly kopjes. These areas are relatively thick and contain palatable browse mainly of Acacia, Maytenus, Commiphora and Euphobia spp. Since the introduction of the grazing programme at Fumbi block in April 2007, the black rhinos residing in the area were observed to co-exist with cattle with no major shifts in the ranging areas being observed.


9

1.8.2. Breeding males black rhinos All the breeding males Melita (24.0 years), James (24.2 years), Mutane (19.0 years), Amuri (20.5 years) and Lacky (11.6 years) maintained their ranging areas. James and Mutane had the smallest home range. James who previously reside on the extreme western edge of former Manyagalo Ranch shifted to Njora and Kona ya Manyagalo probably as a result of the introduction of camels into the extreme corner of the former Manyagalo ranch. Melita who used to roam widely in the previous years was noted to have been pushed to the northern confines by Lacky who established his home range on Mlima mbogo, Isiolo Valley, Mlima Nyeusi and Mlima Nderi areas. Batira had his ranging areas on the western side of the Conservancy but was noted to shift briefly to the southern (former Manyagalo) area. With the influence of James, he returned back to Mawingo area where he seemed to have established his home range between Mutane and Amuri.

Figure 1.9: The ranging areas of four breeding female black rhinos on LWC, 2007 (generated using kernel homerange analysis in ArcView 3.2)


10

Figure 1.10: The ranging areas of five breeding female black rhinos on LWC, January – September 2007 (generated using kernel homerange analysis in ArcView 3.2)

Figure 1.11: Ranging areas of Mama C and Seiya between January – September and October – December, 2007


11

Figure 1.12: Ranging areas of Ndito and Nashami between January – September and October – December, 2007

Figure 1.13: Ranging areas of Oboso and Zaria between January – September and October – December 2007


12

Figure 1.14: The ranging areas of Sonia between January – September and October – December 2007

1.9. Translocation No translocations were undertaken during the year. However, three sub adult males; Batira, Nasha and Sero have reached their adulthood and therefore they should be monitored closely to assess their interaction with other breeding bulls.

1.10. Ear notching of black rhinos In an effort to make all LWC rhinos identifiable by patrol teams and other wildlife management staff, six rhinos were successfully notched with distinguishable ear patterns in December 2007. These were Tupac (2.5 years), Mama C (5.4 years), Sonia’s calf 3 (2.2 years), Zaria’s calf 5 (2.0 years), Stumpy’s calf 7 (2.0 years) and Jazz (4.2 years). To date, 44% of the LWC black rhino population have been ear notched with the current ear notching pattern design while some of the remaining 56% comprising the founder adults have distinguishable marks based on the old ear-notching system. Elimination of clean rhinos has ensured that LWC rhinos are identifiable to all and helps in gathering reliable biological data for informed management intervention strategies.

1.11. Recommendations Ear notching of sub adults rhinos should be an on going exercise in the future as majority of calves are expected to disperse from their maternal ranging areas once they reach the sub adult age bracket.

1.12. Rhino body condition scores The assessment of rhino body condition followed a 1-5 standardized method as described by Reuter and Adcock (1998) and adopted by the African Rhino Specialist Group (AfRSG). Excellent rains received in 2007 resulted to the availability of abundant browse throughout the year. Consequently, like all the other rhinos, the oldest LWC female black rhino (Stumpy = 39


13

years and Solio = 32 years) which were in their mid lactation period registered an improvement in their body condition scores (Table 1.4). Table 1.4: Black rhino body condition scores

No. Rhino Name SexBreeding condition Age (yrs)

Scoring (Jan. 2007)

Scoring (Oct. 2007)

1 Zaria F Late lactation 19.9 3 3+2 Solio F Late lactation 32.1 3 33 Natumi F Late lactation 9.4 3+ 3+4 Mawingo F Non - lactation 18.7 3+ 4-5 Rhinotek F Sub - Adult 6.5 4 46 Ndito F Early lactation 18.1 3+ 3+7 Juniper F Late lactation 19.6 3 3+8 Sonia F Late lactation 16.5 3 3+9 Samia F Early lactation 9.4 3+ 3+

10 Oboso F Mid lactating 7.3 3+ 3+11 Nashami F Mid lactating 9.6 3 3+12 Waiwai F Mid lactating 12.6 3 3+13 Maxxine F Sub - Adult 5.7 4 414 Stumpy F Late lactation 39.1 3 315 Melita M Adult Male 24.1 4 416 Lacky M Adult Male 11.7 4 4+17 Ibong M Adult Male 20.6 4 418 Mutane M Adult Male 19.1 3+ 419 Borana M sub - Adult 3.5 4 420 Elvis M Calf 2.3 3 3+21 Tula F Sub - Adult 3.8 3 322 Batira M Adult Male 8.8 4 4

1.13. Performance of white rhino in Lewa

1.13.1. Status of white rhinos in LWC, 2007 The population of white rhino stood at 37 comprising of 8 calves (0≤3 years); 6 sub adults (3≤6years); 23 adult (>6 years) (Table 1.5; Figure 1.15). The highest proportion of the population comprised of adults with calves and sub-adults comprising of 21% and 16% respectively. This was in contrast with the black rhino population which appeared to have a much younger age distribution. The sex ratio of white rhinos was 1:1 following the translocation of 5 males and 2 females to Ol Pejeta in 2006 and 2007 in a move meant to correct the disparity in the sex ratio in the Conservancy that had led to numerous fights among the breeding bulls. Two births were recorded in 2007 compared to five in 2006. The calves were born to Rinta (3rd calf) and Ngororika (7th calf). Three females (Murembo, Ngororika and Songare) hold the record of having brought fourth seven calves each since their introduction into LWC. Four females follow with five calves each (Figure 1.16). The mean inter-calving interval was 2.5 years with majority of the females’ last calving interval being 2.0-2.1 years. It is predicted that six females (including two females (8.0 years) that were moved from Solio to LWC in 2004) will calve in 2008 (Figure 1.17). This prediction is based on the mean inter-calving interval of each respective female and age at first calving of 7.0 years for first time dams.


14

Table 1.5: Sex and age structures of white rhinos on LWC, December 2007

Age class Males Females Not sexed Sub total Proportion in population

Calves (0≤1 year) 1 0 1 2 5%

Calves (1<3 years) 1 3 2 6 16%

Sub-adults (3<6 years unless calved) 4 2 - 6 16%

Adults (6<30 years) 11 11 - 22 59%

Adults (>30 years) - 1 - 1 3%

Grand total 17 17 3 37 100%

0

2

4

6

8

10

12

Calves (0≤1 years)

Calves (1<3 years)

Sub adults(3<6 years)

Adults (6-30 years)

Adults (>30 years)

Sub

-tota

l

Males Females Unsexed

Figure 1.15: Sex and age structure of white rhinos on LWC, December 2007

0

2

4

6

8

Murembo

Ngororik

a

Songare

Natal

Opondo

Tumbili

Jakw

aiRinta

No.

of c

alve

s/fe

mal

e

Figure 1.16: Number of calves born per breeding female white rhino in LWC: 1984-2007

1.13.2. Growth rate in 2007 To date, the overall growth rate p.a. of white rhino in LWC has averaged 5%. This rate is set to increase as more sub adult females are recruited into the breeding age bracket. This is ideal for

Proportion of population that is actively breeding


15

LWC since stocking rates are still low and there is abundant grass material. Nevertheless, the increase in numbers can only be accommodated if a balanced sex ratio is maintained. However, since this species is not indigenous to Kenya, the national Management Guidelines for White Rhino lay less emphasis on annual growth rates until new sites for releasing excess production become available. This significantly contrasts with the metapopulation management of black rhinos that recommends minimum growth rates of 6% p.a. in the well established sanctuaries in the country. As such, the main justification for keeping white rhinos in Kenya has been proposed as (Okita-Ouma et al., 2007):

- For conservation purposes, where breeding the species supports the reintroduction of white rhino into original (northern subspecies) range.

- For conservation education due to the high visibility of the animal. - As a driver for tourism and community conservation initiatives as it is an attractive

species that is relatively easy to manage, thriving on Kenyan grasslands outside of the trypanosome and tsetse belts.

As for LWC, breeding of white rhinos should be encouraged for the stock to be used as source to restock other areas including suitable community and private conservancies. To date, ** white rhinos have been moved out of the conservancy to establish populations elsewhere.

3736

32343332

3742

0

1

2

3

4

5

6

7

2000 2001 2002 2003 2004 2005 2006 2007 2008

No.

of b

irths

/dea

ths/

tran

sloc

atio

n pe

r ye

ar

10

20

30

40

50

Pop

ulat

ion

size

Births DeathsTranslocated OUT Population s izePredicted births in 2007

Figure 1.17: Trend in white rhino population including births, deaths, translocations in LWC

1.13.3. Sex ratio and translocation With the removal of five males in 2006 and one sub adult female in 2007, the current sex ratio of males : females stands at 1M: 1F, 2 with 3 unsexed. This continued balance should be controlled and surplus males be translocated to other suitable areas.

1.13.4. Overall performance of white rhino on LWC Since the introduction of white rhinos on LWC, 45 calves have been born. Eighteen animals have been translocated out to other conservation areas to enhance tourism and for breeding purposes. The latest movements involved translocation of seven animals to OPC in 2006-2007 as a start towards establishing a viable breeding stock. LWC’s “donor” status of white rhinos in Kenya can be enhanced if the right sex ratios are maintained.

6 1

Translocation IN


16

2. GREVY’S ZEBRA RESEARCH AND MONITORING

2.1. Introduction In the past few decades, Grevy’s zebra have undergone one of the most significant reductions in numbers and range of any African mammal. In 2007, the population was estimated to have hit a low of 1,800 animals (KWS, 2007) down from 15,000 in the 1970’s (Figure 2.1). This represents an approximate reduction of 88% in just 37 years. Similarly, it is only <0.5% of the Grevy’s zebra range that is within protected areas including LWC. The factors contributing to these massive reductions have been discussed in detail by Williams, 2002. Nonetheless, while the above reductions were occurring, Grevy’s zebra continued to extend their range southwards into the Laikipia plateau including LWC, where they received sympathetic reception (Williams, 2002). Consequently, in the past two decades, it is only these areas that have witnessed increases in numbers (Williams, 2002), the most significant being on LWC. Presently, LWC holds at least 430 Grevy’s zebra representing an estimated 23% of the global wild population of this critically endangered species. This figure is up from about 106 animals that were residing in LWC in 1977. The increase in the Conservancy’s population has mainly been from births. As a result, LWC’s population has been recognised as one of the three remaining breeding nucleuses (Rubenstein et al., 2005) in the wild with a potential to increase and be a source for restocking former rangelands. Numbers in LWC have been confirmed annually through two major activities: (i) Annual game counts conducted since 1977 that showed gradual population increases up

to 1999-2000 when remarkable downward oscillations were witnessed (Figure 2.1). This is despite the fact that this population resides inside a PA and is free from anthropogenic factors affecting other populations in pastoralist and livestock dominated areas.

(ii) Foal patrols that have recorded significant births since 2003 when active monitoring of

natality of foals, their survival and recruitment rates was initiated. Since then, this activity has been completed on a monthly basis.

18392571

2000

13718632

106

430

0

3000

6000

9000

12000

15000

1977 1996 1998 2000 2002 2004 2006

Year

No.

in K

enya

's ra

ngel

ands

0

100

200

300

400

500

600

700

No.

in L

ewa

Kenya's Rangelands Lewa

Figure182.1: Grevy’s zebra population trends in Lewa and Kenya’s Rangelands, 1978-2007


17

From above discussion, it is evident that LWC is a critical stronghold of Grevy’s zebra. Therefore, research and monitoring activities being undertaken in the Conservancy are aimed at understanding, and subsequently implementing management interventions to ameliorate factors that may be limiting growth of this population. Furthermore, LWC’s breeding performance can be used as a benchmark to compare the performance of other populations in pastoralist dominated areas where competition for critical resources (water, food and space) is more pronounced. This will provide practical information for decision makers in their pursuit of scaling greater heights in community based conservation in northern Kenya using Grevy’s zebra recovery programmes as a flagship tool. In the past, LWC has collaborated with Earthwatch Institute, St Louis Zoo, Princeton University and Marwell Conservation in an attempt to explain the above limiting factors. Using appropriate methods, research and monitoring activities significantly focussed on explaining:

(i) Inter and intraspecific interaction including competition with Plains zebra; competition among different reproductive classes of Grevy’s zebra; and predation rates.

(ii) Mortality of all age classes, natality, survival and recruitment rates of infants. (iii) Impact of other biotic and abiotic factors in determining movement patterns, use of

space, and exploitation of food and water resources by Grevy’s and Plains zebra. (iv) Susceptibility to diseases and parasitism levels.

In 2007, the specific questions that were addressed by LWC’s Grevy’s zebra research and monitoring programme focussed on:

(i) Explaining factors limiting the growth of the population of Grevy’s zebra in LWC? This query required information on births, foal survival and recruitment rates, inter-birth interval, rate of age specific mortality and causes, and predation rate of both zebra species. Other factors including competition and parasitism have previously been addressed and hence were not investigated in 2007.

(ii) Based on the above findings, what practical and relevant adaptive management

interventions should LWC undertake to encourage Grevy’s zebra population growth?

2.2. Methods The methods used to address the above questions have been described in detail in past annual reports (Chege et al., 2007; Low et al., 2005). In particular, the main activities undertaken were:

a) Monthly foal patrols of Grevy’s zebra to determine natality, survival and recruitment rates. b) Digital identification using a customised database that relied on the unique bar code on the

right rump of Grevy’s zebra. Currently, the reproductive history of about 90% of all adult Grevy’s zebra has been archived in the database.

c) Daily tracking of collared lions, scat collection and subsequent analysis of hair samples.

2.3. Results and discussion

2.3.1. Dynamics of Grevy’s zebra numbers in 2007 A total of 430 Grevy’s zebra were counted in the March 2007 total ground and aerial game census. This was up from 399 animals counted in February 2006. In between the two counts, there were 69 births and 27 confirmed deaths. At the same time, 29 foals born in 2006 were confirmed dead between the two counts. Since emigration and immigration through the northern game gap were not actively monitored and daily reports relied on indirect methods, and while taking births and deaths between the two counts into account, a total of 439 Grevy’s zebra should have been counted in the February census.


18

The difference may be explained by the fact that aerial total counts of species only give a minimal estimate of the population. Minimal emigration and immigration may have had an effect on overall numbers. Also, not all Grevy’s zebra kills may have been detected due to:

a) The height of grass which made detection of carcasses difficult. b) Foals in the 0-6 month age bracket may have been consumed whole. c) Some kills happen at night with hyenas scavenging on the bones before dawn.

2.3.2. Survival and recruitment rates of foals born in 2006 There were 51 foals born in 2006. Eleven and four of these foals were confirmed and suspected dead respectively by December 2006 through monthly foal patrols. All the suspected dead foals were subsequently confirmed dead in 2007. Therefore, as at December 2006, there were only 36 foals that were still surviving. Monthly foal patrols continued in 2007 to determine the fate of the above 36 foals. Fourteen of them were confirmed dead in 2007. Therefore, only 22 foals (46%) born in 2006 survived to become juveniles, and hence stood a high chance of survival due to reduced vulnerability to predation. This overall survival rate was equivalent to 47% that was recorded in 2005 but was significantly higher than 25% and 27% recorded in 2004 and 2003 respectively (Figure 2.2). It should however be noted that Rubenstein et al., (2005) have modelled LWC’s Grevy’s zebra population based on past performances and have shown that in the long term, the Conservancy’s population will only increase in numbers if the overall survival rate of foals born in each year is raised above 50%. Therefore, LWC has fallen short of this target since 2003.

2.3.3. Survival and recruitment rates of foals born in 2007 A total of 69 foals were born in 2007 compared to 51 and 75 born in 2006 and 2005 respectively (Figure 2.3). Nine of these foals were confirmed dead while a further 12 were suspected dead as at December 2007. Foals were suspected dead if they and their mothers were not seen for a minimum period of six consecutive months (i.e. last sighting in June 2007), or their mothers were sighted for two consecutive months without their offsprings. As in the previous years, majority of the confirmed and suspected dead foals were in the 0-6M age bracket further highlighting the vulnerability of foals to predation (Rowen, 1992). Therefore, as at December 2007, the survival rate of foals born in the year was 70% (N=48) (Figure 2.2) majority of which were in the 6-12M age bracket (Figure 2.4). As in the past, this survival rate is expected to reduce further as monthly monitoring of foals continue in 2008.

70%75%73%

54%53%

30%

46%

27% 25%

47%

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

2003 2004 2005 2006 2007Year

Pro

porti

onal

dea

th a

nd s

urvi

val

rate

Death rate Overall survival rate Survival rate as at end of 2007

The minimum overall survival rate of foals born per year required for Lew a's Grevy's zebra population to increase in numbers.

This survival rate is expected to reduce further as monthly foal patrols continue in 2008

Figure192.2: Comparison of survival rate of Grevy’s zebra foals born on LWC, 2003-2007


19

59

75

4451

69

0

20

40

60

80

2003 2004 2005 2006 2007Year

No.

of f

oals

bor

n pe

r yea

r

Figure202.3: Comparison of Grevy’s zebra foals born annually on Lewa since 2003

913

29

0

10

20

30

40

0-3M 3-6M 6-12M

Age bracket of surving foals at end of year

No.

of f

oals

sur

ving

/age

bra

cket

Figure212.4: Age of Grevy’s zebra foals born in 2007 and still surviving at end of the year

2.4. Seasonality of foaling In 2007, timing of foaling of Grevy’s zebra was neither synchronised to the rainy seasons in the year nor in 2006 (Figures 2.5 and 2.6). Rather, foals seemed to have been born throughout the year with the exception of September, November and December 2007. Elsewhere, it has been shown that Grevy’s zebra are usually driven into condition dependent oestrus based on prevailing environmental conditions i.e. they undergo anoestrus in times of dearth of resources and only reproduce when conditions are right. Therefore, it follows that the high grass biomass in LWC (even though it becomes moribund in the dry season), coupled by the perennial water sources, may be enough to trigger and sustain breeding unlike elsewhere in northern Kenya.


20

0

2

46

8

10

12

Jan

FebMar

AprMay

Jun Ju

lAug

Sep OctNov Dec

Month

No.

foal

s bo

rn p

er m

onth

020406080100120140160

Rai

nfal

l (m

m)

No. foals born per month in 2007 Rainfall 2007

Figure222.5: A comparison of numbers of Grevy’s zebra foals born per month on LWC against the 2007 rainfall – note the non-synchrony of foaling with the rains

0

2

4

6

8

10

12

Jan

FebMar

AprMay

Jun Ju

lAug

Sep OctNov Dec

Month

No.

foal

s bo

rn p

er m

onth

0

50

100

150

200

250

Rai

nfal

l (m

m)

No. foals born per month in 2007 Rainfall 2006

Figure232.6: A comparison of numbers of Grevy’s zebra foals born per month on LWC against the 2006 rainfall – note the non-synchrony of foaling with the rains

2.5. Inter-foaling interval Considering that LWC’s Grevy’s zebra reside inside a PA, it follows that this population should reproduce optimally. Therefore, in 2006, simple inter-foaling benchmarks that were based on the duration of the gestation period of Grevy’s zebra (= 13.5 months), to assess the females’ reproductive success were developed. These benchmarks were grouped into the following categories: 13.5-15 months = “Excellent”; while a 24-27 months interval was considered as “Very Poor”. Similarly, inter-birth intervals >27 months were classified as unknown since females may have lost a foal in between without being captured in the Portfolio® Database. All the inter-foaling intervals that have been appropriately captured in the digital database were re-assessed in 2007. Sixty four percent of the inter-birth intervals were rated above “Average” with 30% falling within the “Excellent” category i.e. <15.9 months (Figure 2.7). It would be interesting to gauge the impact of holistic management of grasslands that has been introduced in


21

LWC to assess the response towards reproduction of Grevy’s zebra from the ensuing palatable and more nutritious grass material that significantly attracts grazers including Grevy’s zebra. The above benchmarks may be used by other collaborating partners working in northern Kenya to gauge the level of performance of populations residing in livestock dominated areas (only if individuals in such populations are known and the reproductive history of females has been captured appropriately in relevant databases). The output from such assessments may also be relevant to community based organisations in the region that are in the process of developing core areas for biodiversity conservation using Grevy’s zebra as a flagship species.

19

7

171921

35

0.00

0.10

0.20

0.30

0.40

14-15 Excellent

16-18Good

19-21 Average

21-24Poor

24-27 Very poor

Over 27 Unknow n

Duration of inter-foaling interval(Months)

Pro

porti

onal

inte

r-fo

alin

gin

terv

al

Figure242.7: Proportional inter-birth intervals for Grevy’s zebra on LWC, 2007

2.6. Distribution of lactating females and foals in 2007 As in the previous years, the central parts of LWC and Ngare Ndare continued to be the preferred areas where Grevy’s zebra with foals in the 0-3M age bracket formed nursery herds (Figure 2.8). The distribution of lactating females was observed to be more widespread and away from water sources, as foals were recruited into the 6-12M age bracket. As in 2006, areas frequented by the nursery herds were characterised by:

(i) Proximity to perennial water sources. (ii) Proximity to the swamp that offered safe drinking water and green herbaceous

material throughout the year. (iii) Abundance of Increaser I and II grass species (Cynodon spp) that are ideal for

production of equid milk (Rubenstein, Pers. comm.) (iv) Relatively open vegetation for enhanced visibility against predation. (v) Comparatively short grass (hoof level) arising from prescribed burning and intense

cattle grazing; hence the availability of tender and nutritious grass. In order to imitate the above environmental conditions for the benefit of lactating Grevy’s zebra, it is proposed that that the annual prescribed burning programme focussing mainly on identified kindergarten areas should be continued. This should be complimented by intensive livestock grazing under the holistic management approach that is already in place. The two methods should ensure: opening up of wooded areas to provide increased visibility; while livestock will offer greater trampling of moribund grass thus maintaining relative short grass and sprouting of nutritious herbaceous material preferred by lactating females.


22

Figure252.8: Distribution of Grevy’s zebra foals and juveniles on LWC, 2007


23

3. PREDATOR MONITORING IN LEWA Intensive monitoring of the activities of predators in the Conservancy has been on-going since 2003. The main aim of this exercise is to investigate the impact of predation on prey species with particular focus to the critically endangered Grevy’s zebra and the more commonly occurring Plains zebra. Attention has been paid to the long-term implication of predation on the survival of Grevy’s zebra population in the Conservancy. The population of Grevy’s zebra in the Conservancy has experienced a downward oscillating trend dropping from 630 in 2000 to the current population of 430. Factors that could have potentially led to this reduction in numbers have been investigated in the past with competition with Plains zebra and predation by lions having been identified as possible limiting factors to the growth of the population (Figure 3.1). Since the dynamic of lions have changed on a temporal basis, this project sought to explore further the extent of predation on Grevy’s zebra by lions and suggest possible mitigation strategies to rectify the situation. To achieve the above objective, the following activities that have been described in detail in previous annual reports were completed by gathering and analyzing appropriate data:

(i) Collaring of lions to determine spatio-temporal movement patterns. In 2007, two male lions were collared.

(ii) Tracking of lions on a daily basis to determine movements, behaviour and levels of interaction.

(iii) Identification of lions using operational collars as the reference point; and also their unique whisker spots.

(iv) Collection and analysis of scat to determine the proportion of prey hair in the diet of the target candidates.

(v) Monitoring mortality rates of prey to determine predation levels.

3.1. Lion profile on LWC as at 2007 The population of lions in LWC stood at 25 resident lions in October 2004 (Njonjo, 2004). This number reduced to 16 lions by the end of 2005 and to 12 in 2007. Seven cubs were born in March 2006 while seven males (four sub adults and 3 adults) and a female with her two-year old cubs emigrated out of the Conservancy in the year. The current resident population comprises of two adult females, two sub adult females (migrants), one adult male and seven cubs.

3.2. Collaring, tracking and identification of lions Since 2003, a number of lions have been fitted with collars. By 2005, six collars were still operating. However, some of these collars malfunctioned whereas some lions emigrated out of LWC (2 to Borana Ranch and 3 moved to Samburu Reserve). Therefore, by December 2007, there was only one female with a reliable collar. This collar served as the reference point during the daily tracking of lions since the lioness was part of a definite pride. All the uncollared lions were identified and tracked using spoors that were complimented by Pennycuick and Rudnai’s method (1970) for individual identification and to determine population sizes.

3.3. Collection of scat Scat was collected on a daily basis7 from known lion individuals using the methods listed below in order to increase the chances of encountering the droppings:

• Finding collared individuals and observing them until they produced scat. This was however time consuming.

• Locating the exact areas where lions had been resting and searching for scat once they had relocated to another place.

7 Lion scat is difficult to find due to its high protein content thus making it attractive to smaller predators and scavengers.


24

• Kills were located and scat searched around them. This was a very effective way particularly if the kills were big.

• Opportunistically on road sides.

3.4. Scat and hair analysis The methods used to clean scat and subsequent hair analyses have been explained in detail (Njonjo, 2004; Chege et al., 2007). As a summary, 20 hairs from each scat sample were selected for mounting and identification. Only hairs that had a root were mounted on microscope slides. Hairs were then observed under a light microscope where the basic configuration of the hair i.e. relative width of the medulla and cortex were used to distinguish between hairs of different animals. The hairs were similarly compared with a reference hair collection that has been developed from hairs uprooted from known animals to ensure accuracy.

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Figure263.1: Performance of Grevy’s zebra and lions in LWC, 1996-2007

3.5. Results and discussion

3.5.1. Dynamics of lion population in Lewa The population of lions in LWC in 2007 remained constant at 12 individuals. Nine of these lions, comprising of two lionesses and their seven offsprings formed a cohesive group throughout the year. Two sub-adult females were migrants while 1 male found residence in the Forest. The dynamic of the lion population has changed by a huge margin since March 2006 when seven cubs were born. Prior to this, four sub adult males had emigrated to Borana Ranch. These were subsequently poisoned in 2007 during a wave of poisoning events witnessed in northern Kenya in 2007. Within the same period, two sub adult females disassociated themselves with the natal pride in February 2006. Similarly, two and one adult male moved out of LWC to Samburu National Reserve in July 2006 and April 2007 respectively. Consequently, as at December 2007, the population of lions in LWC stood at 12 compared to 25 resident lions that were in the Conservancy in 2004 (Figure 3.2).


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Figure273.2: Trend in the number of lions on LWC, 2000-2007

3.5.2. Scat and hair analysis in 2007 A total of 38 scat samples were collected and examined for prey hair content in 2007. From each sample, 20 hairs were individually mounted and observed on a light microscope at x10mg and x40mg for identification purposes. Results indicated that zebras (56%) formed the main diet of lions with other species (bovids) contributing only 44% of the diet (Figure 3.3).

0102030405060708090

2004 2005 2006 2007

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porti

on o

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rs in

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sca

t

Equids Other bovids

Figure283.3: A comparison of the proportion of equids versus bovid hair found in lion scat on LWC, 2004-2007 When hairs from the two zebra species were separated, 30% belonged to Grevy’s zebra while 70% were from Plains zebra (Figure 3.4). The bovids that were mainly predated were Impala, Eland and Warthog. These results compare well with the field security personnel incident reports that revealed almost twice as many dead Plains zebra as Grevy’s zebra.


26

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Figure293.4: Comparative assessment of predation rates of Grevy’s and Plains zebra from hairs found in lion scat

3.6. Comparative assessment of predation rates, 2004-2007 Based on the scat analysis results dating back to 2004, zebras have continued to form the main diet of lions although at different magnitudes. The proportions of zebras predated in 2007 (56%) compared well with 2006 when 59% of the diet of lions comprised of zebra but contrasted with 2004 and 2005 when significantly more equids were predated (Figure 3.3). This could be a result of emigration of several adult individuals and sub-adults from LWC to neighbouring ranches and hence the reduction in number of lions to 12 in 2006 and 2007. Again, up to seven of the lions residing in LWC in 2006 and 2007 were cubs. The highest predation rate of zebras was in 2004 when both zebra species were predated equally (Figure 3.4). This coincided with the period when LWC had the highest number of lions comprising of 25 residents and up to 10 migrant lions. The lowest rate of predation of zebras was in 2006 and 2007 when the least number of lions were residing in the Conservancy. The highest proportion of these lions comprised of immatures (7 cubs at a time). During this period, lions appeared to prefer smaller bodied animals including impala and warthog. This contrasted with 2004 when majority of the resident lions were adults staying in large group sizes, and hence, they may have preferred bigger kills to satiate their appetite. This demonstrates the potential benefit that can be achieved by maintaining the number of lions within the lower limit of acceptable thresholds. As a start, a population of up to 12 lions (majority being cubs and sub-adults) appear not to significantly have a negative impact on the population of Grevy’s zebra. .

3.7. Conclusion The benefit of maintaining few lions on LWC was demonstrated in 2006 and 2007 when the population of Grevy’s zebra showed an increment in numbers. LWC will need to maintain such low number of lions in line with the National Strategic Plans and Management Guidelines for Grevy’s zebra (2007). Similarly, proposals have been made to the Carnivore Working Group of KWS so that information on predator/prey dynamics can be incorporated in the Lion and Hyena Management Plan (in preparation).


27

4. TRACKING OF COLLARED GREVY’S ZEBRA IN NORTHERN KENYA Since mid 2006, LWC has collaborated with Save The Elephants, Princeton University, Marwell Conservation, Northern Rangelands Trust, Grevy’s Zebra Trust and KWS to monitor the movement patterns of Grevy’s zebra in northern Kenya. This project relies on GPS/GSM collars worn by 16 animals that are distributed within the key pastoralist dominated Grevy’s zebra strongholds of Laisamis, Barsalinga and the Livestock Marketing Division. The initial software required to download GPS data has been perfected by STE through integration with ArcGIS and Google Earth for real time outputs and hence more robust analysis. The collars collect data on the spatial and temporal movements of target animals at regular intervals (between 30 minutes – 2 hours) as determined by the perceived active/inactive periods of Grevy’s zebra. It should be appreciated that this is the first time that such detailed and real time data on movement patterns of Grevy’s zebra in pastoralist areas is being collected in order to inform management decisions on landscape planning in an attempt to explore ways for peaceful co-existence of this species with pastoralists and their livestock. This is in line with the positive and bold steps being undertaken to establish viable community conservation projects in northern Kenya by various stakeholders. One set of four animals were GSM collared in Laisamis area (northern most community conservancy - 150 km north of LWC) in order to provide movement and range use data on this otherwise elusive population. The Laisamis Grevy’s zebra population is particularly critical since it has been the least monitored/known and yet it has persisted amidst stiff competition from the very high densities of livestock in the area. Three of the four collared animals have already confirmed the extremely large distances that Grevy’s zebra move between the grazing fields and water (Figure 4.1). In particular, one female made two trips in March 2007 from Laisamis to Merile through Mt Baio (probably in response to availability of food and water) and covered a distance of about 280 km in just two weeks (Figure 4.2). Such information will be crucial in informing decisions about the location of the preferred critical resources both in the wet and dry season. Also, this information is crucial to the management of Melako, and indeed all other conservancies in making pragmatic zoning decisions of their areas for future co-existence between Grevy’s zebra and livestock (Figure 4.3). In all the collared animals, it would be critical to perform more detailed analysis to determine factors influencing the movement patterns, including habitats and in response towards the establishment of core conservation areas especially in West Gate and Kalama Conservancies. Livestock and predators are important in this venture and hence there is need to combine the project with other partners working in the region in order to provide such extra data. This need was realised in a stakeholders meeting in November 2007 held at Mpala where data outputs to answer these questions and a roadmap for more detailed analysis and reporting procedures for all users were proposed.


28

Figure304.1: Movement patterns of 3 collared Grevy’s zebra in Laisamis area, Feb. – Jul. 2007

Figure314.2: Movement patterns of one collared female Grevy’s zebra between food and water in Laisamis area covering 280 km from 1-14 Mar. 2007

Mapping by Guy Parker


29

Figure324.3: Movement patterns of Liz (June 2006 – March 2007) showing the extensive distances travelled by the Grevy’s zebra from the National Reserves to the community areas of Kalama and West Gate (mapping by Henrik B. Rasmussen)


30

5. GENERAL WILDLIFE MONITORING

5.1. Annual game census LWC’s annual game count was completed in the first quarter of 2007. Annual counts and daily reports on the abundance and distribution of wildlife are important as they provide trends in the performance of target species, and assist in formulating informed management intervention decisions as necessary. A comparison of the game count figures in 2007 in relation to 2006 and previous counts is shown in Figure 5.1 and Table 5.1. Analysis of the trends of the key wildlife species indicated gradual increment in numbers in 2007 compared to 2006. In particular, the population of Grevy’s zebra rose by 8% while Plains zebra increased by 13% (Figure 5.2). This is encouraging considering the downward trend observed in the population of the two species since 2001. The highest gains were realised by eland (47%) (Figure 5.3), ostrich (33%) and oryx (32%) (Figure 5.4). Giraffe recorded a 29% increase which is quite remarkable considering that this population was reduced in 2003 when 50 individuals were translocated to Meru Park. Waterbuck on the other hand showed a 31% reduction (Figure 5.3). However, it is most likely that several individuals of this species were not sighted due to the thick vegetation experienced on the valleys and riverine areas after the December 2006 – January 2007 flooding.

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Figure335.1: Comparison of the dynamics of some key wildlife species on LWC, 2006-2007


31

Table65.1: Game count figures in Lewa, 2001-2007 SPECIES Jan-01 Jan-02 Feb-03 Feb-04 Feb-05 Mar-06 Mar-07

Beisa Oryx 84 86 62 85 49 69 91Buffalo 125 161 203 233 255 339 343Bush buck >20 >20 >20 >20 >20 >20 >20Cheetah 21 10 7 8 8 8 5Eland 151 121 108 137 214 169 248Elephant 150 28 157 216 297 392 256Gerenuk 17 15 11 7 11 11 ~10Giraffe 236 245 215 177 173 147 189Grant's gazelle 162 192 167 261 258 320 362Greater kudu 38 37 33 36 >20 >20 >20Hippo 1** 2** 2 2 2 2 2Hartebeest 9 7 4 2 2 2 2Impala 627 749 760 679 836 739 829Jackal 0 0 >15 >12 >12 >12 >12Klipsringer >8 >8 >8 >6 >8 >8 >8Leopard 1 7 >8 >8 8 8 >8Lion 8 20 18 28 24 16 12Ostrich 119 98 65 68 48 36 48Black rhino 29 29 32 36 40 48 53White rhino 30 31 32 32 39 36* 36Sitatunga 21 23 16 16 14 14 10Warthog 88 194 136 129 170 140 163Waterbuck 149 170 64* 52 116 134 93Burchell's zebra 1264 1039* 1025 1102 1094 970 1098Grevy's zebra 556 487 462* 435 448 399 430

Species present but not counted Key- Spotted hyena - Dik dik > (greater than)- Stripped hyena - Civet cat < (less than)- Crocodile - Serval cat ~ (approximately)- Duiker - Caracal cat * (census after translocation out of Lewa)- Genet cat - Reed buck ** (census after translocation into Lewa)- Aardvark - Steinbok 0 (species present but not seen during count)


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Figure345.2: Trend in Grevy’s and Plains zebra numbers, 1999-2007

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Figure355.3: Trend in Buffalo, Eland and Waterbuck numbers, 1999-2007

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Figure365.4: Trend in Oryx and Ostrich numbers, 1999-2007


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6. ECOLOGICAL MONITORING

6.1. Rainfall in 2007 In 2007, the mean annual rainfall received on the 11 rain stations spatially distributed in LWC was 620 mm. This amount was slightly lower than the 758 mm received in 2006 but was significantly higher than 286 mm received in 2006. It was also way above the long-term mean of 513 mm averaged from 1972 to 2006 (Figure 6.1). March – May and October – December were the rainy seasons. This compared well with the bimodal distribution pattern of rainfall in LWC. However, all the months (except September) recorded some amount of rain. Sambara station received the least rainfall (140 mm) while Lewa HQ, Matunda and Soboiga stations with 498mm each received the highest amount (Figure 6.2).

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Figure376.1: Monthly rainfall received in LWC (2005-2007) against the long-term mean

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Figure386.2: Amount of rainfall received per station in LWC, 2007


34

6.2. Vegetation monitoring Monitoring the status of vegetation in LWC has been an ongoing process since mid-1990s. The main goal of vegetation monitoring is to provide trends in the condition and performance of both grass and woody vegetation habitats. The information gathered is important as it guides the management in making informed decisions including areas suitable for application of prescribed burning; zones in need of protection as a result of aggravated destruction by elephants - and hence protection and regeneration of suitable woody vegetation habitats for black rhinos and other browsers; and blocks to be subjected to intensive cattle grazing. There were four types of vegetation monitoring activities undertaken in 2007. These were:

1. Grass assessment 2. Woody vegetation monitoring 3. Prescribed burning 4. Fixed-point photography

6.2.1. Grass assessment The annual grass assessment survey was completed in order to estimate the biomass of grass and composition of herbaceous material so as to determine areas that could be subjected to prescribed burning and intensive cattle grazing. The two methods compliment each other as they achieve varying results -hence, the method chosen is dependent on the desired output. The methods used to estimate the biomass of grass are described in detail by Botha (1999). In particular, any block with grass biomass >5000kg/ha and dominated by increaser I grass species is considered to be moribund and hence should be considered for prescribed burning.

6.2.2. Prescribed burning Even though several blocks had grass biomass >5,000kg/ha., only one block was subjected to prescribed burning in order to remove the moribund stocks of herbaceous material. All the other blocks were recommended to be subjected to a phased cattle grazing under the holistic management approach. However, as it will take sometime to attain the desired number of cattle for meaningful results, in future, grazing will be complimented with cool burns in order to achieve desired and extensive results. Cool burns are preferred because:

(i) They cause minimal damage to the woody vegetation. (ii) Ensure that low biomass of grass is maintained for an extended period of time. (iii) Cause minimal damage to soil nutrients.

6.2.3. Fixed point photography The major objective of fixed point photography is to monitor trends in vegetation changes over time. Such changes are brought by varying browsing pressure and changing rainfall regimes. Fixed point photography was completed in the 28 permanent vegetation monitoring points.


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7. MANAGEMENT ISSUES

7.1. Improvement of rangeland for Grevy’s zebra

7.1.1. Background In the past several years, the standing crop of grass biomass in LWC has witnessed considerable build up after the rainy seasons since it is not kept in check by the low densities of the bulk feeders. These vegetative components comprising mainly of Increaser I8 grass species (Pennisetum stramineum and P. mezianum) become moribund upon the onset of the dry season due to extensive underutilisation. The grass species also become highly fibrous, lignified and of low quality, and hence are not preferred by the grazers. In the past, one of the management techniques in LWC has been to apply fire to eliminate such rank grass. Similarly, such burning reduces the risk of fire and changes the composition of grass species. Even though cool burns have been successfully used in the past, experience has shown that the rate of success of such intervention on woody species depends on the amount of rainfall received in the subsequent years. Therefore, the impact on woody vegetation cover and density has been noted to be remarkably affected when the rains fail. The intended outcome is exacerbated by the fact that fire is non-selective and covers large areas. In order to deviate from the above trend, in 2007, LWC adopted part of Allan Savoury’s holistic management technique for rangeland rehabilitation and restoration that uses large herds of grazing cattle as a tool. However, grazing may be selective, but this can be overcome if sufficient numbers of cattle that are confined in space are used. This approach is set to achieve sustained environmental, economic and social benefits in LWC through:

1. Increasing grazing and wildlife capacity by allowing large herds of community cattle to graze in defined and controlled blocks.

2. Improving soil health, biodiversity of rangelands and grasslands through removal of unpreferred grass species while promoting growth of more diverse and palatable grass.

3. Increasing profits and enhancing livelihoods of neighbouring communities by linking them to better markets for sale of healthy cattle on a trial basis.

The above project has been tied to promoting one of the main objectives of the Conservancy i.e. long term conservation of endangered species - mainly Grevy’s zebra and black rhino by:

a) Using local community cattle to intensively graze and trample on the moribund grass material to change the composition and encourage regeneration of quality grasses that are palatable to Grevy’s zebra. In the long term, extending the rangelands available to this endangered species thus triggering its population increase.

b) Replacing the rangeland improvement methods currently practiced on LWC (mainly prescribed burning), with a more environmental friendly technique that will significantly reduce damage to woody vegetation.

At the same time, the long term implementation of holistic management for rangeland rehabilitation is meant to replace fragmentary decision-making and short-term solutions with a system that encompasses a whole, long-lasting process of restoring damaged land and managing healthy land. Similarly, this technique can be used to restore declining wildlife populations like Grevy’s zebra – this being the main objective of LWC’s approach.

8 Increaser I species can be defined as grass and herbaceous species which increase when rangeland is under utilised or selectively grazed.


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The holistic grazing management system as proposed by Alan Savoury is based around the concept of grass growth, and promoting grazing in accordance with the phases of growth of grass. These phases are (Felicity, 2007):

• Phase 1: Pasture just beginning to grow from seed or root reserves. Energy for growth coming from the roots. This is the first phase of growth, so there is low pasture biomass (bulk). Very high nutritional value of the grass. High quality but low quantity grass. Grazing during this time will cause the plant to have to start from scratch again, calling on diminished root reserves for energy.

• Phase 2: Grass growth really starting to take off. Energy for growth comes from photosynthesis as there is enough leaf available, good bulk of grass whilst still reasonably high nutrition levels. Ideal time to graze to balance needs of the grass and needs of the grazing animal.

• Phase 3: Grass lignifies. High bulk of pasture but quality declines rapidly. High quantity but low quality grass. Plant focuses energy into replenishing root reserves. Grazing at this stage will not harm the pasture plants but nutritional quality for animals is low.

The basis of Savoury’s grazing system focuses on grazing the pasture plants when in phase two and allowing a sufficient period of rest post grazing to enable plants to recover and re-grow using photosynthesis. Constant grazing of an individual plant reduces the leaf area available for photosynthesis thus the plant must use root reserves to re-grow, weakening its energy reserves and the capacity of the plant to respond to stress. The grazing system needed to allow plants sufficient periods of rest and recovery involves a system of rotation, as constant grazing means individual plants are overgrazed and eventually die out of the system, creating gaps. Presently, LWC’s grazing programme is geared towards smothering grass that is already in phase 3, with subsequent progression towards phase 2 and managing grazing at this level in future.

7.1.2. Methods In order to realise the above objectives, two movable holding pens comprising of 40 metal frames each, and that can be dismantled to ease portability, were constructed in the year to confine community cattle grazing in LWC at night. Each frame measured 3x1.8m. The pens were mounted in identified blocks that had standing grass biomass >5,000 kg/ha. and that were dominated by the highly fibrous Increaser I grass species that are not preferred by wild grazers. Previously, extensive studies on rangeland condition in LWC have shown that any block with standing grass biomass >5,000kg/ha. and that is dominated by Increaser I grass species is usually moribund and needs to be burnt (Trollope, 1999). The pens were erected on designated areas that also served as intensive grazing blocks with up to 800 herds of cattle mainly from the neighbouring communities and those from LWC being grazed in two tight bunches to maximise trampling and cropping of grass. These herds were later paddocked and over-nighted in the bomas to again achieve continued grass smothering. This programme targeted two types of herds:

1. Community cattle coming through LWC for quarantine and destined for the market. 2. Community and LWC cattle for grazing purposes to trample and smoother the grass.

Bomas was shifted/rotated in the same block in a systematic manner (Figure 7.1) in order to achieve an even smothering effect. In order to attain optimal results, the experimental design (frequency of pen rotation) was varied severally to suit LWC’s ecological and environmental conditions. It was realized that for effective trampling, each herd should have at least 500 herds of cattle and be held in each pen for a minimum of 7 days in the dry season and a maximum of 3 days in the wet season. However, this was dependent on other factors including soil type and transition between seasons.


37

Figure397.1: Diagrammatic representation of the systematic rotation of cattle pens

7.1.3. Results and discussion Since the inception of the grazing programme, the two pens that occupy 1,146m² each have been shifted 49 times as at December 2007. Hence, the total area that has been subjected to intensive trampling and immediate reduction of the standing crop of grass biomass to almost zero was 56,154 m² compared to the initial biomass before boma erection of >5,000 kg/ha. (Figure 7.2 and 7.3) This was in addition to intensive trampling and grazing on the blocks.

Figure407.2: A section of the cattle pen showing the impact of intense cattle trampling for 5 days There was also significant regeneration of quality and palatable grass in the boma sites as a result of extensive manuring. This acted as an attractant to grazing herbivores. The sprouting grass was non-fibrous and un-lignified. It was expected that this grass would attract the lactating female Grevy’s zebra, and by extension formation of kindergartens in such sites.

Continue the shift

Starting pen

r=19.1m

Completely trampled and manured area with ~zero grass biomass


38

Figure417.3: A comparison of location of cattle pen sites versus non-pen sites/non-grazed areas showing the impact of trampling and subsequent phased grass regeneration

7.1.4. Impact of the programme and future Remarkable grassland rehabilitation in terms of trampling and smothering the moribund grass material, and subsequent regeneration of palatable grass that is preferred by grazers including Grevy’s zebra, has been realised since the inception of the programme. Similarly, substantial economic returns to the communities have been achieved through sale of healthy cattle. Therefore, in future, this programme will remain an integral component of the adaptive wildlife related management techniques being implemented by LWC.

7.1.5. Recommendations 1. In order to achieve extensive optimal results and suit LWC’s ecological and environment

conditions, at least 4 bunches of community cattle with a minimum of 500 herds per bunch, should be grazed and paddocked within LWC. This will ultimately increase the output from intense grazing and trampling as demonstrated in Figure 7.3, and the subsequent regeneration of quality grass. Such extensive and quality grass lawns are expected to attract abundant wildlife including the Grevy’s zebra due to the palatability of herbaceous material. It is hypothesised that provision of such palatable feed will provide enough nutrients hence improve the health of Grevy’s zebra thus triggering breeding. In the end, LWC’s vision of restocking the former rangelands of Grevy’s zebra with its current stock will be realised.

2. Realising a target of 2000 herds of cattle can be achieved through strengthening the

current LWC and Il Ngwesi livestock grazing partnership. Similarly, over time, the option of bringing NRT affiliate community conservancies on board should be explored and a partnership agreement developed.

3. However, the use of bomas represents a tiny proportion of the land available. Hence,

there will be need to compliment this programme with the traditional prescribed burning exercises especially on the P. stramonium dominated black cotton soil areas.

Site of cattle pen 1

Site of cattle pen 2

Un-grazed site


39

7.2. Management of invasive species Invasive plant species have been known to cause significant threat to water production, natural landscape and the integrity of biodiversity. Similarly, invasive species always cause ripple effects to the environment (Foxcrofti et al., 2006). As a result, invasive species are regarded as one of the greatest threats to global biodiversity. Therefore, such species should be eradicated using the most convenient techniques to avoid spread.

7.2.1. Invasive and alien species in LWC There was an unprecedented proliferation of conspicuous invasive species in LWC following the extremely high rainfall received between November 2006 and January 2007. Concerted efforts were made to characterize and map these species so as to prioritise elimination. The most widespread species was Datura stramonium that dominated Willy Robert’s exclusion zone, Manyagalo Swamp and along Sirikoi River (Figure 7.4) together with most of the disturbed areas e.g. road drains and abandoned cattle bomas. Willy Robert’s area had previously been cultivated by the owners of the former Manyagalo Ranch. The area also receives extremely high run-off of rain water from the adjacent small scale farmers in Manyagalo Community who do not actively control the spread of invaders unless they are on cultivated land. Of extreme worry is that even though D. stramonium flourished significantly, it was not utilised by browsers. Similarly, it was found to prevent growth of grass and other undercover herbaceous material. Other commonly identified exotic species in LWC included cactus (Opuntia exaltata, O. vulgaris, Lantana camara and Lippia javanica (Table 7.1). Opuntia was originally meant to demarcate LWC from the neighbouring communities in the south eastern side. Even though Opuntia is not currently a major threat on the Conservancy, it appears to be gaining root further from its original confines and hence need regular monitoring for its timely eradication. Elsewhere in the world e.g. northern Australia, Opuntia had become a major invasive species that had to be removed using specially designed eradication programmes (Giesen et al., 2007). L. camara is a major invasive species in Australia and Southeast Asia and hence the need for its regular monitoring and eradication to avoid spread. Table 7.1: Exotic plant species found in LWC as at Dec. 2007 (from Giesen et al., 2007) Species Family Notes Achyranthes aspera Amaranthaceae Originally from China & Australia; common

at Lewa in riverine vegetation Ageratum conyzoides Asteraceae Originates from America; in disturbed areas

Chenopodium alba Chenopodiaceae

Originally from Northern Hemisphere.

Datura stramonium Solanaceae

Originates from America; in disturbed areas

Galinsoga parviflora Asteraceae Originates from South America; in riverine areas

Lantana camara Verbenaceae Originates from South America; disturbed hill and outcrop areas

Opuntia exaltata Cactaceae Originates from South America; disturbed places near Lewa boundary, esp. along roads

Opuntia vulgaris Cactaceae Originates from South America; disturbed places near Lewa boundary, esp. along roads

Tagetes minuta Asteraceae Originates from South America; widespread in many habitats


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7.2.2. Control of invasive species in LWC Throughout the year, close collaboration with the Logistics Department was maintained and majority of the D. stramonium were mechanically removed before the fruiting stage. In 2006, the following recommendations, that have already been effected, were proposed for adoption and be maintained in future to ensure timely eradication of invasive species. That in order to realise the most cost effective results of invasive species eradication, prioritisation for control and ultimately elimination of the alien species on the Conservancy should to a great extent be guided by the following four principles (McNeely et al., 2001):

(i) The current extent of the species in and around LWC needs continuous definition. This should involve continuous mapping of the distribution and intensity of the focal species (Figure 7.4).

(ii) Documentation of the current and potential impacts to native flora and fauna. (iii) Characterisation of the value of habitats that the species has or may invade. (iv) Available cost effective and efficient measures to control and eliminate the species.

This may involve slashing, uprooting or application of herbicides.

Based on the above guiding principles, the following recommendations were proposed:

(i) The existing early detection and monitoring programmes of invasive species in LWC should be enhanced. Currently, monitoring and control programmes have been ad hoc. These need to be regularised by the Research and Logistics Departments as part of their annual work plans.

(ii) Regular surveys and monitoring need to be conducted on known infestations and key areas especially on the former Manyagalo Ranch and Willy Roberts exclusion zone. To achieve this, permanent belt transects should be placed in infested areas to measure the rate of spread or otherwise reduction, especially of D. stramonium.

(iii) For effective results, D. stramonium and other invasive species should be eliminated before the fruiting stage. Slashing D. stramonium at the ground level was found to be effective as it did not necessarily lead to regeneration or coppicing.

(iv) Application of herbicides should be considered for extensive stands of invasive species. Likewise, control actions should be integrated with existing management plans including controlled burning.

(v) In collaboration with the Community Department, sensitise communities especially in Manyagalo to eliminate D. stramonium on their land to reduce rates of runoff especially during the rainy seasons.


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Figure427.4: Distribution of Datura stramonium on LWC, 2006 – 2007


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7.3. Impact of the Marathon The annual Lewa Safaricom Marathon entered its eighth year in 2007. Since its inception, the event has raised substantial funds for biodiversity conservation and human welfare both in the Conservancy and in northern Kenya. Just like in any other tourism industry, in the recent past, the event has raised concern for a variety of perceived or actual ecological and social impacts, including wildlife disturbance and displacement, habitat damage and pollution within the Conservancy. Much of these impacts may be due to lack of effective management and control (Roe et al., 1997) due to the size of the event, and therefore, can be regulated if effective mechanisms for mitigation are put in place. While all activities carried out during the marathon period are meant to be environmental friendly, the impact to the environment and wildlife is voluminous. This section is meant to bring into focus some of the ecological impacts that were witnessed during the 2007 marathon event. The impacts have been categorised into four: Depletion of resources; pollution; vegetation degradation and disruption of animal behaviour; and physical impacts.

7.3.1. Depletion of natural resources The event attracted over 6,000 participants who were distributed in various campsites and action sites pre, during and post marathon as shown in Table 7.2. Majority of these were accommodated in the conservancy thus placing a high demand on local resources in order to satiate participation appetite. Of these participants, an estimated 5,000 found their way into the finish point while up to 2,000 were at the starting point thus exerting pressure into the fragile environment. In the campsites:

• Up to 87 fires were lit in just two nights thus exerting pressure on firewood that had to be collected pre-marathon in the Conservancy.

• Water was extensively utilised during the event for various reasons. This extended to even watering the marathon route. In the campsites, up to 59 showers were erected to cater for the huge influx of people.

• Trampling and offroad driving especially in the main campsite areas and the finish point thus creating a maze of tracks with subsequent creation of bare ground, thus disrupting the ecological balance.

• Too many vehicles and people significantly reduce the visitor game viewing experience on the Conservancy’s paying guests.

7.3.2. Disturbance to biodiversity • The effect on the distribution of wildlife one week to, during and a week after the

marathon. In particular, wildlife species were physically pushed off from all the main blocks that were traversed by the marathon route. Two zones were identified as having the most significant wildlife disturbance: (i) critically disturbed zone situated in the central parts of LWC that was a no go zone to wildlife on the days preceding, and during the marathon day; and (ii) highly disturbed zone lying within and along the marathon route where wildlife were physically pushed away on the day of the event (Figure 7.5). This obviously increased disturbance forcing the wildlife to shift their behaviour in relation to drinking and feeding patterns. Mapping of the distribution of wildlife was completed one week prior to the marathon. The same event was repeated one day after the event. The results were significantly contrasting with majority of the wildlife virtually absent in the above 2 mentioned zones in the post marathon survey.

• Wildlife deaths arising from fences erected temporary around the campsites – at least six wildlife individuals comprising of 2 Plains zebra, 1 Grevy’s zebra, 2 Impala and a Warthog have been killed by the temporary fences erected around the campsites in the


43

last three marathons. Similarly, lions appear to have perfected their hunting skills by chasing their prey against the fences for easy catch.

• Mowing of grass on the campsites (e.g. Safaricom village, Digby’s), on water stations, spectator points and spectator routes adversely affected distribution of wildlife and had an impact on overall biodiversity within these focal sites.

• Impact of having to move the odd dangerous and hand raised animals away from the Lewa HQs because of the dangers to the marathoners who do not realise that the semi-tamed animals are not pets. The buffalo had to be moved in 2007 only for it to come back to the HQs. Sera, the hand-raised giraffe succumbed in 2006 when she twisted herself in the fence line after been confined in the workshop enclosure.

7.3.3. Pollution • This took various forms. The most significant ones were in the form of air (dust) and

noise pollution. Up to 1,000 vehicles were witnessed during the event majority of which never adhered to rules and regulations of a protected area. LWC and its affiliate parties’ vehicles were observed not to follow the well documented and known Lewa Standard Procedures. There were two helicopters and a spotter plane during the entire duration of the marathon. At least 10 caravans landed on the airstrip in just two days, and not to forget other numerous light aircrafts (Table 7.2).

• Solid waste and littering – up to 11,400 bottles of water were distributed in just two days with the subsequent disposal through burying or burning. There were mountainous loads of garbage generated from the campsites and the finish area that witnessed temporary markets of all sorts of food items (Table 7.2).

• Sewage – up to 123 temporary toilets were erected within the campsite and on the water points. Along the course, relieve was in the bush.

• Aesthetic pollution – this was in terms of tents where up to 531 tents were erected. There were other numerous one-man tents that were not accounted for, and that were erected within staff the compounds.

7.3.4. Physical impacts • Roads experienced very high usage with over 1,000 cars gaining entry into LWC in just

two days. This figure excluded LWC and other affiliate parties’ vehicles. The roads that experienced the highest usage were those linking the Lewa HQs with tourist outlets, campsites and the main access roads to Matunda (Figure 7.5). These roads experienced significant impact while delivering supplies, preparing the marathon route and while spectating.

• Construction activities and infrastructural development including too many tents, showers, toilets etc.

• Mowing of campsites and spectator routes.

7.3.5. Compromise in wildlife monitoring activities: • At least 56 wildlife (rhino) monitoring teams are usually deployed on a daily basis to offer

security and surveillance of wildlife all over LWC. However, rhino surveillance activities significantly decrease in the days running up to the event and during the event as most of the security teams are tied up on security duties at the marathon campsites. This increases the potential to lose rhino to poachers and indeed all other wildlife.


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Activity No. People No. Tents No. ToiletsNo.

Showers RubbishWater Bottles No. Fires Cut Grass Cars Planes

Self Catering Campsite 350 100 10 10 Plenty 500 30 Yes 100 YesSafaricom Village 500 225 Plenty 5 Yes 50 YesMaridadi Campsite 85 50 Plenty 5 Yes 10 YesVIP Campsite 100 50 50 25 Plenty 1,150 5 Yes 30 YesHighland Campsite 10 10 2 2 Yes 200 2 Yes 3Bomb Campsite 30 15 6 6 Plenty 200 2 Yes 5 YesParliament Campsite 20 15 8 8 Plenty 200 2 Yes 10 YesCommunity Campsite 100 8 5 Bush Plenty 200 5 Yes 10Security Campsite 30 6 2 2 Yes 100 2 Yes 5Guest to LWC staff 250 10 - - Yes 300 10 Yes 25 YesOther Campsites 20 10 2 2 Yes 50 5 Yes 4 Yes

Water Stops - people who camped at site 20 12 8 4 Yes 4 Yes 8 Yes

Course

150 staff, 1000

spectators 0 Bush 0 Plenty 0

Yes - spectator

points 2002 Helicopters 1

S/CubFinish 5,000 20 20, Bush 0 Too much 10 Yes 500 YesStart 2,500 0 10, Bush 0 Plenty Yes 200 Yes

General 1,00010 caravans in 2

days

6,500

2,000

Table87.2: Some pertinent data on the impact of Safaricom Marathon

Figure437.5: Areas that witnessed significant wildlife disturbance due to the Marathon


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8. REFERENCES Amin, R., Okita-Ouma, B., Adcock, K., Emslie, R.H., Mulama, M. & Pearce-Kelly, P (2006) An Integrated Management Strategy for the Conservation of Eastern Black Rhinoceros. Int. Zoo.Yb 40:118-129. Zoological Society of London. Chege, G., Kisio, E. & Mwololo, M. (2007) Lewa Wildlife Conservancy: Research & Monitoring Annual Report 2006. Lewa Wildlife Conservancy, Isiolo, Kenya. Emslie, R. & Brooks, M. (1999) African Rhino: Status survey and action plan. ix + 92. IUCN Gland and Cambridge, UK. Ix + 92 pp Foxcrofti, L. C., Lotter, W. D., Runyoro, V. A. & Mattay P. M. C. (2006) A review of the importance of invasive alien plants in the Ngorongoro Conservation Area and Serengeti National Park. Afr. J. Ecol., 44:404–406 Giesen, W., Giesen, P. & Giesen, K. (2007) Habitat changes at Lewa Wildlife Conservancy. KWS (2001) Conservation and management strategy for the black rhino (Diceros bicornis michaelli) in Kenya (2001 – 2005). Kenya Wildlife Service, Nairobi Low, B., Chege, G., Kisio, E., Mwololo, M., Kirathe, J., Njonjo, D. (2005) Lewa Wildlife Conservancy: Research & Monitoring Annual Report 2004. Lewa Wildlife Conservancy, Isiolo, Kenya. McNeely, J.A. (2001) The great reshuffling: human dimensions of invasive alien species IUCN, Gland. Njonjo, D. (2004) Lewa Wildlife Conservancy Predator Project: Annual Report. Lewa Wildlife Conservancy, Isiolo. Okita-Ouma, B., Amin. R. & Kock, R. (2007) Conservation and Management Strategy for the Black Rhino and Management Guidelines for the White Rhino (2007-2011). Kenya Wildlife Service, Nairobi. Okita-Ouma, B., Amin. R., Adcock, K., Emslie, R., Pearce-Kelly, P. & Kock., R. (2007) A positive turning point in black rhino conservation in Kenya. In Conservation and Management Strategy for the Black Rhino and Management Guidelines for the White Rhino (2007-2011) (Okita-Ouma, B., Amin. R. & Kock, R. (2007). Kenya Wildlife Service, Nairobi. Rowen, M. (1992) Mother-infant behaviour and ecology of Grevy's zebra, Equus grevyi. PhD Thesis. Yale, New Haven. Rubenstein, D., Kirathe, J., Oguge, N., Muoria, P. & Chege, G. (2005) Zebras of Kenya: Unravelling the relationship between Grevy’s and Plains Zebra. Poster Presented at the Annual EWI Conference, Boston. U.S.A. Williams, S.D. (2002) Status and action plan for Grevy's zebra (Equus grevyi). In Zebras, Asses and Horses (ed. P.D. Moehlman), pp. 11-27. IUCN, Gland, Switzerland and Cambridge.


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9. APPENDIX 1: BREEDING PERFORMANCE AND CALVING PREDICTION FOR BLACK AND WHITE RHINO ON LEWA, 1985 - 2007

BLACK RHINO

No. Name Date bornAge (yrs) Mother 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

Age at 1calving

(yrs)1 2 3 4 5 6 7

1 Juniper 28/6/88 19.5 Juno 7.6 3.2 2.3 2.2 2.3 - - - 2.52 Mawingo 1/6/89 18.6 Solio Cow ** 2.2 2.8 1.7 1.5 1.6 - - 2.03 Meluaya 25/1/96 11.9 Juniper 8.4 1.9 - - - - - - 1.94 Ndito 1/1/90 18.0 Solio Cow 9.3 3.2 2.2 2.1 - - - - 2.55 Nyota 1/12/91 11.9 Stumpy 7.8 2.7 2.4 1.5 - - - - 2.26 Solio 1/1/76 32.0 Solio Cow ** 3.1 3.5 3.9 3.2 2.1 2.9 2.3 3.07 Sonia 23/8/91 16.4 Solio 7.1 4.7 2.4 - - - - - 3.68 Stumpy 1/1/67 39.0 Solio Cow ** ** 3.9 2.8 2.2 3.0 2.0 - 2.89 Waiwai 4/7/95 12.5 Solio 6.8 2.1 2.3 - - - - - 2.210 Zaria 9/3/88 19.8 Solio 7.8 2.3 2.1 3.0 2.2 - - - 2.411 Nashami 16/7/98 9.5 Stumpy 7.612 Natumi 26/9/98 9.3 Solio 6.713 Samia 10/9/98 9.3 Sonia 8.214 Oboso 09/10/00 7.2 Zaria 5.415 Seiya 26/4/99 8.7 Ndito 5.5 2.7 2.716 Tana 10/10/00 7.2 Stumpy -17 Rhinotek 16/8/01 6.4 Juniper -18 Maxxine 13/6/02 5.6 Waiwai -19 Mama C 22/7/02 5.4 Ndito -

7.3 2.5

No. Name Date bornAge (yrs) Mother 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 03

Age at 1calving

(yrs) 1 2 3 4 5 6 71 Murembo 1/1/76 32.0 Solio Cow 6.0 2.9 2.6 1.9 2.8 1.8 2.0 - 2.32 Natal 1/1/89 19.0 Natal Cow 8.1 2.3 2.2 2.2 2.2 - - - 2.23 Ngororika 1/1/81 27.0 Solio Cow ** 2.0 2.2 2.6 2.1 2.1 2.1 - 2.24 Opondo 1/1/86 22.0 Natal Cow ** 2.3 2.6 2.5 2.5 - - - 2.55 Songare 1/1/80 28.0 Solio Cow ** 4.0 2.2 4.0 2.0 2.0 2.0 - 2.76 Tumbili 1/1/86 22.0 Natal Cow 8.3 2.2 3.2 3.4 3.6 - - - 3.17 Jakwai 1/1/87 21.0 Solio Cow 9.4 2.2 2.9 1.9 2.1 - - - 2.38 Rinta 3/6/94 13.6 Ngororika 7.7 2.5 2.5 - - - - - 2.59 Tale 1/1/00 8.0 Solio Cow -10 Titilei 1/1/00 8.0 Solio Cow -11 Samawati 11/6/02 5.6 Natal -12 Schini 11/12/02 5.1 Tumbili -Key Year female born 7.9 Mean inter-calving interval = 2.5

Quarter of the year calf bornFuture calving based on respective female's last inter-calving intervalFuture calving based on respective female's mean inter-calving intervalExpected date of first calving = 7 years)

** History unknown

04 06 0700 01 02 03

04 05

WHITE RHINO

00 01 02 0906 07 08

Calving intervalsMean

calving interval/ female

Mean age at 1st calving =

08

Mean age at 1st calving = Mean inter-calving interval =

Mean calving interval/ female

Calving Intervals

0905

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