How numbers of nesting sea turtles can be over-estimated by … · 2017-02-11 · Supplementary...

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How numbers of nesting sea turtles can be over-estimated by nearly a factor of two Nicole Esteban1, Jeanne A. Mortimer2,3, Graeme C. Hays4,†

1Swansea University, Department of Biosciences, Swansea, SA2 8PP, Wales, United Kingdom 2Turtle Action Group of Seychelles, P.O. Box 1443, Victoria, Mahé, Seychelles, and 3University of Florida, Department of Biology, Gainesville, FL 32611, United States of America 4Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Warrnambool, VIC 3280, Australia Author for correspondence: Graeme Hays, e-mail: [email protected]

Electronic supplementary material: Supplementary Table S1 | Evidence of 50 subsequent clutch depositions by 10 green turtles using Fastloc-GPS transmitter locations.

Supplementary Table S2 | Estimates of the mean clutch frequency grouped by region for green turtles and loggerhead turtles measured around the World by beach patrols. Supplementary Figure S1 | Timing of nesting activities during estimated clutch frequency intervals

Supplementary Figure S2 | The 221 Fastloc-GPS locations of Turtle 21914 around Diego Garcia from 11 July until 14 October 2015. Supplementary Figure S3 | The 7 Fastloc-GPS locations of Turtle 21915 around Diego Garcia from 11 July until 29 September 2015.

Supplementary Figure S4 | The 73 Fastloc-GPS locations of Turtle 21923 around Diego Garcia from 8 July until 31 August 2015. Supplementary Figure S5 | The 181 Fastloc-GPS locations of Turtle 29358 around Diego Garcia from 14 July until 30 September 2015. Supplementary Figure S6 | The 586 Fastloc-GPS locations of Turtle 117568 around Diego Garcia from 9 July until 21 October 2015. Supplementary Figure S7 | The 395 Fastloc-GPS locations of Turtle 117569 around Diego Garcia from 13 July until 28 September 2015. Supplementary Figure S8 | The 80 Fastloc-GPS locations of Turtle 117570 around Diego Garcia from 6 July until 10 August 2015. Supplementary Figure S9 | The 203 Fastloc-GPS locations of Turtle 117571 around Diego Garcia from 4 July until 14 August 2015.

Supplementary Figure S10 | The 246 Fastloc-GPS locations of Turtle 117572 around Diego Garcia from 5 July until 31 August 2015. Supplementary Figure S11 | The 33 Fastloc-GPS locations of Turtle 117573 around Diego

Garcia from 6 July until 19 July 2015.

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Supplementary Table S1 | Evidence of 50 subsequent clutch depositions by 10 green turtles using Fastloc-GPS transmitter locations. Nests 1 preceded transmitter attachment

on the index beach in Diego Garcia, British Indian Ocean Territory (BIOT) in July 2015.

Successive nests (2-9) were determined using multiple lines of evidence: filtered Fastloc-GPS

(F), Haulout of >20 min (H) or Interpolation based on modal inter-nesting interval (I). Local times

are used (GMT +6 h). Fastloc-GPS stopped working on 21915 between nests 1 and 2 so

subsequent Argos data were used.

Turtle ID

Size CCL (cm)

Nest 1 Tagged Date/hr

Nest 2 Evidence Date/hr








21914 101.5 - H H F F H H F H F H

10 Jul 22:20

24 Jul 22:05

8 Aug 00:03

20 Aug 19:50

4 Sep 01:23

16 Sep 23:32

30 Sep 23:10

13 Oct 23:01

21915 111.0 - H H H H H H H

7 Jul 22:30

20 Jul 05:26

31 Jul 06:00

11 Aug 22:37

23 Aug 06:00

4 Sep 22:43

16 Sep 06:00

29 Sep 08:41

21923 114.0 - H H F F H

8 Jul 22:00

20 Jul 21:49

3 Aug 00:06

13 Aug 20:05

30 Aug 01:37

29358 108.5 - F H F F I F F

14 Jul 22:30

27 Jul 22:03

8 Aug 21:32

20 Aug 21:41

2 Sep 06:00

15 Sep 05:53

28 Sep 04:50

117568 110.0 - F H F H F H F H F H F H F H F H

9 Jul 21:45

23 Jul 05:29

3 Aug 00:07

15 Aug 23:56

29 Aug 03:07

10 Sep 23:08

24 Sep 22:49

6 Oct 20:21

20 Oct 23:15

117569 113.0 - F H F F F H F H F H

13 Jul 23:30

26 Jul 20:17

7 Aug 04:55

19 Aug 21:18

1 Sep 23:45

14 Sep 23:42

27 Sep 00:30

117570 107.0 - F H F F H

6 Jul 00:30

17 Jul 02:08

28 Jul 22:44

6 Aug 00:26

117571 111.0 - F H F H F

4 Jul 05:20

17 Jul 03:14

29 Jul 21:14

13 Aug 04:03

117572 112.5 - F H F F F H F H

6 Jul 00:30

16 Jul 20:52

26 Jul 20:37

5 Aug 20:33

20 Aug 06:06

31 Aug 04:28

117573 105.0 - F H

6 July 22:10

18 Jul 02:45

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Supplementary Table S2 | Estimates of the mean clutch frequency (CF) grouped by region for green turtles and loggerhead turtles measured around the World by beach patrols. In some cases observed clutch frequency (OCF) and estimated clutch frequency (ECF)

are also indicated. Where there were multiple estimates for the same location the most recent

value was used. The midpoint of a range was taken. Note that the composition of the various

tag types and the methodologies employed have evolved over the decades. Tag retention is

lower for Monel tags than for non-corroding Inconel and Titanium tags; and double tagging is

more effective than applying only a single tag to each female. Bracketed citations refer to the

following review papers:

Dodd CK. 1988 Synopsis of the biological data on the Loggerhead sea turtle Caretta caretta

(Linnaeus 1758). US Fish. Wildl. Serv. Biol. Rep. 88(14). 110 pp.

Hirth HF. 1980 Some aspects of the nesting behavior and reproductive biology of sea turtles.

Amer. Zool., 20, 507-523.

Hirth HF. 1997 Synopsis of the biological data on the green turtle, Chelonia mydas (Linnaeus

1758). Biological Report 97(1), 1-129. US Department of Interior.

Schroeder BA, Foley AM, Bagley DA. 2003 Nesting patterns, reproductive migrations, andadult

foraging areas of loggerhead turtles. In: Bolten AB, Witherington BE. (Eds.), Loggerhead sea

turtles, 114–124. Smithsonian Books Washington, DC.

Species Location Clutch Frequency

Methods Citation Reference

Green turtle, Chelonia mydas

Mediterranean C. mydas Mediterranean

Cypress (N) 1.9-3.5 later pooled to 2.9-3.1

1992-93 (Plastic Jumbotags Dalton); 1994-97 Plastic Supertags (Dalton); 1998-2000 Titanium tags; since 1997 PIT tags. OCF & ECF calculated.

Broderick et al. 2002

Broderick AC, Glen F, Godley BJ, Hays GC. 2002. Estimating the number of green and loggerhead turtles nesting annually in the Mediterranean. Oryx 36(3), 227-235.

C. mydas Mediterranean (Same as above) Paper discusses energetic & size issues


Broderick AC, Glen F, Godley BJ, Hays GC. 2003. Variation in reproductive output of marine turtles. J. Exp. Mar. Biol. Ecol. 288, 95-109.

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Atlantic Ocean C. mydas Florida

Atlantic coast, Brevard County (Melbourne Beach) USA

OCF = 2.4 ECF = 3.0 (n=145).No correlations with size

Monel tags—double tagging Based on two seasons: 1991-1992. 12 km long study beach

Johnson, Ehrhart 1996

Johnson SA, Ehrhart LM. 1996 Reproductive ecology of the Florida green turtle: clutch frequency. J. Herpetology 30(3), 407-410.

C. mydas Tortuguero, Costa Rica

2.8 (Range 1-8) .Remigrants had higher CFs than previously untagged

Monel tagging, single tag per female

Carr & Hirth 1962; Carr et al. 1978 [Hirth 1980] [Hirth 1997]

Carr A, Hirth H. 1962. The ecology and migrations of sea turtles, 5. Comparative features of isolated green turtle colonies. Amer. Mus. Novitates 2091, 1-42. Carr A, Carr MH, Meylan AB. 1978 The ecology and migrations of sea turtles, 7. The west Caribbean green turtle colony. Bull. Amer. Mus. Nat. Hist. 162,1-46.

C. mydas Surinam 2.9 (Range 1-9) N=602 Remigrants had higher CFs than previously untagged.

Monel tagging Schulz 1975 [Hirth 1980]

Schulz JP. 1975. Sea turtles nesting in Surinam. Neder. Comm. Int. Natuur. Med. 23, Stichting Natuur. Suriname (Stinasu), Verhandeling No. 3.

C. mydas Ascension Island

3.0 (SD=1.65) N=78; Remigrants had higher CFs than previously untagged.

Monel tagging, single tag per female

Mortimer & Carr 1987

Mortimer JA, Carr A. 1987. Reproduction and migrations of the Ascension Island green turtle (Chelonia mydas). Copeia 1987(1), 103-113.

C. mydas Ascension Island

6.3 (n=40) Combination of VHF radio-telemetry and Argos-linked Fastloc™ GPS devices (in Dec 2011-Jan 2012)

Weber et al. 2013

Weber N, Weber SB, Godley BJ, Ellick J, Witt M, Broderick AC. 2013. Telemetry as a tool for improving estimates of marine turtle abundance. Biol. Conserv. 167, 90-96.

Pacific Ocean C. mydas Colola Beach,

Michoacán, Mexico

Mean OCF= 2.5; Mean ECF = 3.1

Double tagging: one monel and one plastic roto-tag on each turtle. Clutch frequency calculated for each of a random sample of 50 turtles per year (from an average annual population of ~394 females—assuming 3.1 clutches per female).

Alvarado-Díaz et al. 2003

Alvarado-Díaz J, Arias-Coyotl E, Delgado-Trejo C. 2003. Clutch frequency of the Michoacán Green Sea turtle. J. Herpetology 37(1), 183-185.

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C. mydas Playa

Cabuyal, Costa Rica (Pacific coast)

ECF=4.3 (SD=2.3)

Double tagged: 1 Inconel; 1 PIT Surveyed 1.4 km long beach intensely

Tomillo et al. 2015

Tomillo PS, Roberts SA, Hernández R, Spotila JR, Paladino FV. 2015. Nesting Ecology of East Pacific Green Turtles at Playa Cabuyal, Gulf of Papagayo, Costa Rica. Marine Ecology 36(3), 506-516.

C. mydas Nombre de Jesús, Costa Rica (Pacific coast)

ECF= 3.67 (SD=1.79); Ultrasound= 5.13 (SD=1.32).

Patrol from July to Nov 2009. PIT tags & Ultrasound scanner

Blanco et al. 2012

Blanco GS, Morreale SJ, Vélez E, Piedra R, Montes WM, Paladino FV, Spotila JR. 2012. Reproductive output and ultrasonography of an endangered population of East Pacific green turtles. J Wildlife Management 76(4), 841-846.

C. mydas Playa Naranjo, Costa Rica (Pacific coast)

ca 2 (Range 2-4)

Probably single monel tagging

Cornelius 1976 [Hirth 1997]

Cornelius SE. 1976. Marine turtle nesting activity at Playa Naranjo, Costa Rica. Brenesia 8, 1-27.

C. mydas Galapagos Islands, Ecuador

ca 3 (Range 1-7)

Double tagging: one monel and one plastic roto-tag on each turtle.

Green 1994 Green 1979 [Hirth 1997]

Green D. 1994. Galapagos sea turtles: an overview. Pages 65-68 in B. A. Schroeder BA, Witherington BE (compilers) Proceedings of the thirteenth annual symposium on sea turtle biology and conservation. NOAA Tech. Memo. NMFS-SEFSC-341,281 pp. Green D. 1979. Double tagging of green turtles in the Galapagos Islands: Marine Turtle Newsletter 13, 4-9.

C. mydas French Frigate Shoals, Hawaii

1.8 (Range 1-6) N=208 females, at East Island

Monel tags from 1973-76. Inconel from 1976 onward – 2 to 3 tags per female.

Balazs 1980; Pilcher et al. 2012 [Hirth 1980] [Hirth 1997]

Balazs GH. 1980. Synopsis of biological data on the green turtle in the Hawaiian Islands. NOAA-TM-NMFS-SWFC-7. October 1980. 141 pp.

Pilcher NJ, Chaloupka MY, Woods E. 2012 Chelonia mydas (Hawaiian subpopulation). The IUCN Red List of Threatened Species 2012, e.T16285718A16285879.


4 (Range: 1-9) at East Island;

Based on saturation surveys using Inconel tags, during 1988-92 (G. Balazs unpubl. data)

Tiwari et al. 2010

Tiwari M, Balazs GH, Hargrove S. 2010. Estimating carrying capacity at the green turtle nesting beach of East Island, French Frigate Shoals. Mar. Ecol. Prog. Ser. 419, 289-294.


Study sites: 1.8 (Balazs 1980) 4 (Range: 1-9) at East Island (Tiwari et al. 2010); 2.8 (Range: 1-6) at Tern Island (Pepi 2002, MSc study, cited in Tiwari et al. 2010).

Cites previous studies

Balazs et al. 2015

Balazs GH, Van Houtan KS, Hargrove SA, Brunson SM, Murakawa SKK. 2015 A review of the demographic features of Hawaiian green turtles (Chelonia mydas). Chel. Conserv. Biol. 14(2), 119-129.

C. mydas Ogasawara Islands, Japan

3.9 Females captured early in season, confined in ‘breeding pool’ prior to slaughter.

Kazuo Horikoshi, pers comm. in Mortimer & Carr 1987.

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C. mydas Sarawak

Islands ca 6-7 (Range 1-11)

Monel metal tags (saturation tagging)

Hendrickson 1958

Hendrickson JR. 1958 The green sea turtle, Chelonian mydas (Linn.) in Malaya and Sarawak. Proc Zool Soc Lond 130, 455–535.

C. mydas Heron Island (Southern Great Barrier Reef) Australia

4.5 (Range 3-6)

Monel tags; One per female

Bustard 1972 [Hirth 1980]

Bustard R. 1972. Sea turtles: Their natural history and conservation. Taplinger Publ. Co., New York.

C. mydas Heron Island (Southern Great Barrier Reef)

5.06 (SD=1.99) Range=1-9 N=878

Titanium tags, double tagging. Saturation tagging attempted.

Limpus 2008 Limpus C. 2008. A biological review of Australian marine turtle species. 2. Green turtle, Chelonia mydas (Linnaeus). Queensland Government, Environmental Protection Agency. 96 pp.

C. mydas Bramble Cay (Northern Great Barrier Reef)

6.2 (SD=2.1) Range=1-10 N=684

Monel tags, double tagging. Saturation tagging achieved (1976-77, 1979-80).

Limpus et al. 2001

Limpus CJ, Carter D, Hamann M. 2001. The green turtle, Chelonia mydas, in Queensland: the Bramble Cay rookery in the 1979–1980 breeding season. Chel. Conserv. Biol. 4(1), 34–46.

C. mydas Xisha Island, China

ca 3 No methodology described. Note: This CF figure may be based on literature search.

Huang Chu-Chien 1982 [Hirth 1997]

Huang Chu-Chien. 1982 Distribution of sea turtles in China seas. Pages 321-322 in K. A. Bjomdal (ed.), Biology and conservation of sea turtles. Smithsonian Institution Press, Washington D. C., 583 pp.

Indian Ocean C. mydas Huyong

Island, Thailand (Andaman sea)

3.7 ± 2.3 (n = 9) for turtles began nesting October; 7.0 ± 2.9 (n = 5) for turtles began nesting in November. (Varied by month over 12 yr period).

Combination PIT and Inconel tagging year-round. Looks like near saturation tagging of a small population.

Yasuda et al. 2008

Yasuda T, Kittiwattanawong K, Klom-in W, Arai N. 2008 Seasonal changes in reproductive output of a year-round nesting population of the green turtle Chelonia mydas at Huyong Island, Thailand. Amphibia-Reptilia 29, 559-566.

C. mydas Huyong Island, Thailand (Andaman sea)

3.9 + 2.1 (n=11); 6.6 + 2.8 (n=9) (Depended on time of year turtle first encountered)

Combination PIT and Inconel tagging year-round. Looks like near saturation tagging of a small population.

Yasuda et al. 2006

Yasuda T, Tanaka H, Kittiwattanawong K, Mitamura H, Klom-in W, Arai N. 2006 Do female green turtles exhibit reproductive seasonality in a year-round nesting rookery? J. Zool. (Lond.) 269, 451-457.

C. mydas Aldabra atoll 3-5 (unpublished data; prelim estimate)

Titanium tags: both single and double tagged

Mortimer et al. 2011

Mortimer JA, von Brandis RG, Liljevik A, Chapman R, Collie J. 2011 Fall and Rise of the Nesting Green Turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: Positive Response to Four Decades of Projection (1968-2008). Chel. Conserv. Biol. 10(2), 165-176.

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C. mydas Mayotte Island 3.03 + 0.37 (max=10 in a female)

Monel tags, single tag per turtle. Year-round monitoring from 1 Jan 1998 to Dec 2005.

Bourjea et al. 2007

Bourjea J, Frappier J, Quillard M, Ciccione S, Roos D, Hughes G, Grizel H. 2007 Mayotte Island: another important green turtle nesting site in the southwest Indian Ocean. Endangered Species Res. 2007(3), 273-282.

C. mydas Tromelin Island

2.75 + 1.46 Monel tags, single tag per turtle. 3-mo-long period during 2009/10 nesting peak (8 Dec-8 Mar).

Derville et al. 2015

Derville S, Jean C, Dalleau M, Le Gall J-Y, Ciccione S, Bourjea J. 2015. Long-term monitoring of green turtle nesting on Tromelin Island demonstrates stable reproduction and population parameters. Chel. Conserv. Biol. 14(1), 11-20.

C. mydas Tromelin Island

3.5 Monel tags, single tag per turtle. Entire island surveyed over 3 mos period.

Le Gall 1988; LeGall et al. 1986

Le Gall JY. 1988. Biologie et évaluation des populations de tortues vertes Chelonia mydas des atolls Tromelin et Europa (Océan Indien S.O.). Mésogée 48, 33–42. Le Gall J-Y, Bosc P, Chateau D, Taquet M. 1986. Estimation due nombre de tortues verte femelles adultes Chelonia mydas par saison de ponte à Tromelin et Europa (Océan Indien) (1973-1985). Oceanogr. trop. 21(1), 3-22.

C. mydas Europa Island 2.8 Monel tags, single tag per turtle. Surveys focused on the Plage de la Station (Station Beach) < 2 km in length, over 3 mos period

Le Gall 1988; LeGall et al. 1986

C. mydas Querimbas archipelago, Mozambique

2.5 + 1.8 Titanium tagging; ~ 29% of nests tagged

Garnier et al. 2013

Garnier J, Hill N, Guissamulo A, Silva I, Witt M, Godley B. 2012 Status and community-based conservation of marine turtles in northern Querimbas Islands (Mozambique). Oryx 46(3), 359-367.

C. mydas Karan Island, Saudi Arabia

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Titanium tags: double tagged. Karan Island surveyed 3 months 1986; 1 month 1987

Miller 1989 [Hirth 1997]

Miller JD. 1989 Marine turtles: Vol. 1: an assessment of the conservation status of marine turtles in the Kingdom of Saudi Arabia. MEPA Coastal and Marine Management Series, Report No. 9, pp. 1-209 Ministry of Defense and Aviation, Kingdom of Saudi Arabia.

Loggerhead turtle, Caretta caretta

Global C. caretta Global CF= 1-6

(maximum 7) [Dodd 1988]

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Mediterranean

C. caretta Zakynthos, Greece

CF = usually 1-3 clutches / season

Flipper tagging Margaritoulis 1983 [Dodd 1988]

Margaritoulis D. 1983 The inter-nesting interval of Zakynthos loggerheads. Pages 135-144 in N.S. Margaris. M. Arianoutsou-Faraggitaki. and R.J. Reiter (eds.). Adaptations to terrestrial environments. Plenum Press. New York.

C. caretta Mediterranean Cyprus (N)

1.2-4.6 later pooled to 1.8-2.2

1992-93 (Plastic Jumbotags Dalton); 1994-97 Plastic Supertags (Dalton); 1998-2000 Titanium tags; since 1997 PIT tags. OCF & ECF calculated


C. caretta Mediterranean No change, but paper discusses energetic & size issues


Broderick AC, Glen F, Godley BJ, Hays GC. 2003 Variation in reproductive output of marine turtles. J. Exp. Mar. Biol. Ecol. 288, 95-109.

Atlantic Ocean C. caretta South

Carolina, USA CF = mean 2-3 (range=1-6)

Flipper tagging Talbert et al. 1980 [Dodd 1988]

Talbert OR, Stancyk SE, Dean JM, Will JM. 1980 Nesting activity of the loggerhead turtle (Caretta caretta) in South Carolina. I: a rookery in transition. Copeia 1980, 709-719.

C. caretta Little Cumberland Island, Georgia, USA

CF average = 2.5

Flipper tagging Richardson & Richardson 1982 [Dodd 1988]

Richardson JI, Richardson TH. 1982. An experimental population model for the loggerhead sea turtle (Caretta caretta). Pages 165-176 in K. Bjorndal (ed.), Biology and conservation of sea turtles. Smithsonian Institution Press, Washington, DC.


CF = 1.84-1.97

Flipper tagging Stoneburner 1981 [Dodd 1988]

Stoneburner DL. 1981. Summary of the loggerhead sea turtle research project conducted at Canaveral National Seashore, Cumberland Island National Seashore, Cape Lookout National Seashore: A final report 1980. NPS Res./Resour. Manage. Rep. No. 39.


During 1974-1984, annual variation in CF: from CF=2.8 in 1982; to CF=4.2 in 1979

Flipper tagging Frazer & Richardson 1985 [Dodd 1988]

Frazer NB, Richardson JI. 1985. Annual variation in clutch size and frequency for loggerhead turtles, Caretta caretta, nesting at Little Cumberland Island, Georgia, USA. Herpetologica 41, 246-251.

C. caretta Georgia, USA CF max = 7 clutches

Flipper tagging Lenarz et al. 1981 [Dodd 1988]

Lenarz MS, Frazer NB, Ralston MS, Mast RB. 1981. Seven nests recorded for loggerhead turtle (Caretta caretta) in one season. Herpetol. Rev. 12,9.

C. caretta S. Brevard County, Florida

CF=3.4 Flipper tagging [Schroeder et al. 2003]

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C. caretta Keewaydin Island, Florida

CF=3.8-4.1 Flipper tagging Addison 1996 [Shroeder et al., 2003]

Addison DS. 1996 Caretta caretta (loggerhead sea turtle). Nesting frequency. Herpetol. Rev. 27, 76.

C. caretta Jupiter Island, Florida, USA

CF range =1-6 Experienced females (remigrants) laid more clutches than neophytes (1.61 v 1.37)

Flipper tagging Lund 1986 [Dodd 1988]

Lund F. 1986 Nest production and nesting-site tenacity of the loggerhead turtle, Caretta caretta, on Jupiter Island, Florida. Unpubl. M.S. Thesis. University of Florida, Gainesville, 32 pp.

C. caretta Casey Key, Southwest Florida, USA

Flipper tagging CF: 2.2 Argos CF: 5.4. Mode=5

Comparison of: Flipper tags & PIT tags on 6 km of beaches; and ARGOS transmitters.

Tucker 2010 Tucker AD. 2010 Nesting site fidelity and clutch frequency of loggerhead turtles are better elucidated by satellite telemetry than by nocturnal tagging efforts: implications for stock estimation. J. Exp. Mar. Biol. Ecol., 48-55.

Pacific Ocean C. caretta Columbia,

South America

CF could lay at least 4 times/season & possibly more

Kaufman 1975 [Dodd 1988]

Kaufmann R. 1975 Studies on the loggerhead sea turtle, Caretta caretta (Linne) in Colombia, South America. Herpetologica 31, 323-326.

C. caretta Japan CF = 2 Iwamoto et al. 1985 [Dodd 1988]

Iwamoto T, Ishii M, Nakashima Y, Takeshita H, Itoh A. 1985 Nesting cycles and migrations of the loggerhead sea turtle in Miyazaki, Japan. Jpn. J. Ecol. 35, 505-511.

C. caretta Eastern Australia

CFrange = 1-6 Limpus 1985 [Dodd 1988]

Limpus CJ. 1985 A study of the loggerhead sea turtle, Caretta caretta, in eastern Australia. Unpubl. Ph.D. Dissertation. University of Queensland, St. Lucia, Australia.

C. caretta Mon Repos, Eastern Australia

CF mean = 3.41 SD=1.2 Range =1-6 n=1207

Limpus 2008 (cited Limpus 1985 above)

Limpus C. 2008 A biological review of Australian marine turtle species. 1. Loggerhead turtle, Caretta caretta (Linnaeus). Queensland Government, Environmental Protection Agency. 67 pp.

Indian Ocean C. caretta Oman CF = 4.4 Satellite

telemetry Rees et al. 2008 [Schroeder et al. 2003]

Rees AF, Saadi SA, Coyne MS, Godley BJ. 2008 Internesting habitat and nest frequency at a globally significant loggerhead nesting population described using Argos tracking. NOAA Tech. Mem. NMFS-SEFSC-569, p. 55.

C. caretta Tongaland CF typical = 4-5 4.5 [Hirth] 4 to 5 [Dodd]

Hughes 1974 [Hirth 1980] [Dodd 1988]

Hughes GR. 1974. The sea turtles of south-east Africa. I. Status, morphology and distributions. II. The biology of the Tongaland loggerhead turtle Caretta caretta L. with comments on the leatherback turtle Dermochelys coriacea L. and the green turtle Chelonia mydas L. in the study region. Invest. Rep. Nos. 35, 36. South African Assoc. Mar. Biol. Res. Oceanographic Res. Institute, Durban, South Africa.

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Supplementary Figure S1 | Timing of nesting activities during estimated clutch frequency intervals (a) The daily timing of 286 locations 19

associated with turtles moving onto the back reef and nesting beaches, indicative of nocturnal emergences to nest (86.364% occurring between 20

sunset and sunrise, with >99.95% occurring between sunset and sunrise ±2 h). (b) The intervals between 50 estimated successive nests for 10 21

individuals derived from satellite tracking data (mean = 12.42, SD = 1.401, minimum = 8, maximum = 16).22

(a) (b)

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23 Supplementary Figure S2 | The 221 Fastloc-GPS locations of Turtle 21914 around 24

Diego Garcia from 11 July until 14 October 2015. Open red circles represent locations 25

relating to 8 nesting events. Projection: Mercator. 26

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12

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29 Supplementary Figure S3 | The 7 Fastloc-GPS locations of Turtle 21915 around Diego 30

Garcia from 11 July until 29 September 2015. 5 Argos and haulout locations were used to 31

generate nesting locations after the last Fastloc-GPS location on 14 July. Open red circles 32

represent locations relating to 5 nesting events. 1 additional nesting event was interpolated. 33

Projection: Mercator. 34

35

13

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Garcia from 8 July until 31 August 2015. Open red circles represent locations relating to 5 39

nesting events. Projection: Mercator. 40

41

14

42


Diego Garcia from 14 July until 30 September 2015. Open red circles represent locations 45

relating to 6 nesting events. One additional nesting event was interpolated. Projection: 46

Mercator. 47

48

15

49


Diego Garcia from 9 July until 21 October 2015. Open red circles represent locations 52


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Diego Garcia from 13 July until 28 September 2015. Open red circles represent locations 58


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Diego Garcia from 6 July until 10 August 2015. Open red circles represent locations 64


66

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72

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78

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Garcia from 6 July until 19 July 2015. Open red circles represent locations relating to 2 82

nesting events. Projection: Mercator. 83

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