Rabbit Control Research Can learnings from possums be applied to rabbits? B. Warburton, G. Nugent,...
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Transcript of Rabbit Control Research Can learnings from possums be applied to rabbits? B. Warburton, G. Nugent,...
Rabbit Control ResearchCan learnings from possums be
applied to rabbits?
B. Warburton, G. Nugent, P. Fisher,J. Parkes, R. Clayton, G. Morriss
Outline
• Main research and operational aim
• What have we learnt from possums?
• Is there potential to apply this knowledge to rabbit control?
• Planned research projects
Current standard operational practice 2-3 kg/ha of 12g 1080 baits170-250 baits/ha for ≤ 20 possums & rats/ha
Why are we not using less?
Research and Operational Aim:To reduce sowing rates and cost
(a) Cereal pellet bait operations (n= 90)
0
4
8
12
16
20
1973-77 1978-82 1983-87 1988-1992 1993-97 1998-2002
Years
Mea
n so
win
g ra
te (k
g/ha
)
0
10
20
30
40
50
60
Cos
t ($/
ha)
(b) Carrot bait operations (n=51)
0
5
10
15
20
25
30
35
1973-77 1978-82 1983-87 1988-1992
1993-97 1998-2002
Years
Mea
n so
win
g ra
te (k
g/ha
)
0
10
20
30
40
50
Cos
t ($/
ha)
From Dave Morgan
What have we learnt?Prefeed…1
Cautious feeders Gluttons
< 1bait
0
12
24
36
48
60
72
84
1 2 3
Encounter
Bai
t ea
ten
(g)
>2 baits
0
12
24
36
48
60
72
84
1 2 3
Encounter
Bai
t ea
ten
(g)
Possum pen trials
What have we learnt?Prefeed…2
• Prefeed significantly increases the kill achieved
Possums
0%
50%
100%
0 1 2
N Pre feeds
% s
urv
iva
l (s
.e.)
Rats
0%
50%
100%
0 1 2
N Pre feeds
% s
urv
iva
l (s
.e.)
Results of field trial at Whirinaki (Nugent et al 2008)
Before pre-feeding During pre-feeding
Before pre-feeding During pre-feeding
5 days before prefeeding 5 days during prefeeding
What have we learnt?Prefeed…3
GPS location data from a possum before and during prefeed.
Prefeed line
What have we learnt?Bait aversion
3.00kg/ha broadcast
0
50
100
1 2 3 4 5 6 7 8 9Bait cluster #
% b
ait
ea
ten
Carrot Apple Cereal
Unpoisoned
0
50
100
1 2 3 4 5 6 7 8 9Bait cluster #
% b
ait
ea
ten
0% 50% 100%
Rata RdCereal
Te TehiCereal
Rata RdCarrot
Te TehiCarrot
% of baits
Gone Part eaten Untouched
After a carrot operation After a cereal operation
(b) After sowing
0
20
40
0.5 3.5 6.5 9.5 12.5
%
(a) Before sowing
0
20
40
0.5 3.5 6.5 9.5 12.5
%What have we learnt?
Bait fragmentation
Bait weight class (g)
Before sowing
0
10
20
30
0-1 2-3 4-5 6-7 8-9 10-1112-13 >14
% After sowing
0
10
20
30
40
0-1 2-3 4-5 6-7 8-9 10-1112-13 >14
%
No 7 bait RS5 bait
Bait weight class (g)
What have we learnt?Reducing the sowing rate…1
Sown at 3kg/ha
● ≤ 2g = sublethal● > 2g
What have we learnt?Reducing the sowing rate…2
Sown at 0.25kg/ha
What have we learnt?Reducing the sowing rate…3
Sown at 0.25kg/ha
100m
Potential to apply similar approach to rabbits…1
• Rabbit densities:
Common abundance index used is rabbits per spotlight kilometre (up to 300) Moller et al. 1999. Density estimates within patches up to 50 rabbits/ha
(mean 19/ha).
• Current bait sowing rates: 25 to 45kg/ha (up to 60kg/ha) At 30kg/ha and 5g baits applying 6000 baits/ha!
• Toxic loadings registered: Carrot = 0.02% (LD99 = c. 3mg/kg) – Need three 5-g baits Cereal = 0.04 & 0.06%
• For carrot bait at 0.02% 1080 and 50 rabbits/ha need atmost c. 150 baits (750g/ha).
Potential to apply similar approach to rabbits…2
0
10
20
30
40
50
60
70
<0.25 0.25 - 0.5 0.5 - 1.0 1.0 - 2.0 2.0 - 4.0 4.0 - 8.0 8.0 - 16.0
Perc
enta
ge
Weight class (g)
Carrot bait (Reliance cutter unscreened)Weight distribution
From Batchelor (1982)2007 ERMA 1080 reassessment:•All carrot bait for aerial application to be screened at a mean weight of 6g•Ground laying of bait does not have to be screened.
So what is the bait size 1080 conc distribution of sown bait?
Potential to apply similar approach to rabbits…3
0
5
10
15
20
25
30
35
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Mea
n ra
bbit
s/km
Year
Secondary vs primary controlPrimary control (aerial 1080) needed after 8 years
Secondary control (helicopter shooting, night shooting, spot
poisoining)
From Lough 2009
• Can secondary control maintain the gains of RHD and remove the need for repeat primary control using 1080? – at what costs?
• How can conventional control and RHD be effectively integrated?
Planned Research…1• Project 1. A review paper: To re-assess the single dose
LD100 for 1080 and pindone.• Project 2. An analysis of bait size distributions and 1080
toxic loadings for cereal, screened carrot, and unscreened carrot before and after sowing.
• Project 3. Construct a probabilistic model of numbers of bait encounters needed to kill rabbits of different size and susceptibility – as done by Batchelor (1982) and Frampton et al. (1999).
• Project 4. An observational study of how rabbits react to carrot and cereal baits at first ever encounter, and test acceptance of a one-shot ‘perfect’ carrot bait with and without prefeeding.
Planned Research…2
• Project 5. Home range use and effect of prefeed on foraging patterns (GPS) – implications for trickle sowing.
• Project 6. Rabbits, coprophagy, and pindone. Can pindone be used as a one-hit application?
• Project 7. Secondary control – extending the benefits of RHD – what is effective and at what cost?
• Project 8. Integrating RHD with conventional control – development of a DSS for end-users.
• Project 9. Developing a web-based bibliography of all published and unpublished rabbit research literature:
- Jim Bell’s (MAF rabbit group)- Rabbit & Land Management Programme (special thanks to Don Ross for making MAF and RLMP material freely available)
From the late Jim Bell’s photo collection
A typical scientist!!