Marine Ecology Progress Series
MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.
Impact Factor2.3 (JCR 2026 release)
Article Acceptance Rate51.3% (2025)
Median Time in Review137.5 days (2025)
Total Annual Downloads1.586.389 (2026)
DOI: https://doi.org/10.3354/meps14997
copiedTemporal patterns in space use by immature hawksbill turtles: insights from Fastloc-GPS tracking on Reunion Island
Juvenile stages are critical yet understudied periods in the life cycle of endangered hawksbill turtles Eretmochelys imbricata. We used Fastloc-GPS tracking to examine the home range and movement patterns of 19 immature hawksbills (mean ± SD curved carapace length = 56.1 ± 10.2 cm) across 5 neritic habitats around Reunion Island (mean tracking duration = 230 ± 133 d). Eight tags were physically recovered, providing access to memory records, including wet/dry and sea temperature data. We investigated their spatiotemporal movement patterns, site fidelity, and habitat use dynamics across daily, monthly and seasonal timescales. The results revealed strong site fidelity, with 95% utilization distributions (UDs) averaging 0.79 km2 and remaining highly stable over time. Daily activity patterns were closely linked to sun angle, with the greatest spatial extent when the sun was highest, and resting behaviours at night. Surface time, derived from wet/dry data, peaked in the morning and increased by a factor of 1.5-1.6 at lower sea temperatures (range = 24-28°C). Nocturnal site selection strongly influenced the extent of the home range, with most turtles favouring the night shelter closest to their core foraging ground. While small-scale exploratory movements (<5 km) were common (11 individuals), 2 turtles undertook long-range migrations (>1000 km), suggesting that juveniles transition through multiple developmental sites before reaching adulthood. These findings provide new insights into the spatial variability of immature hawksbills, alternating between highly conservative behaviour and exploration, emphasizing the need for regional conservation strategies and site-specific protection.
KEYWORDS
Arendt MD, Segars AL, Byrd JI, Boynton J and others (2012) Seasonal distribution patterns of juvenile loggerhead sea turtles (Caretta caretta) following capture from a shipping channel in the Northwest Atlantic Ocean. Mar Biol 159:127-139 Crossref
Avens L, Ramirez MD, Goshe LR, Clark JM and others (2021) Hawksbill sea turtle life-stage durations, somatic growth patterns, and age at maturation. Endang Species Res 45:127-145 Crossref
Barret M, Schneider F, Ragé A, Ciccione S (2025) Two decades of rehabilitation data reveal threats faced by sea turtles in Reunion Island. Ind Ocean Turtle Newsl 41:03
Bates D, Mächler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J Stat Softw 67:1-48 Crossref
Bellini C, Sanches TM, Formia A (2000) Hawksbill turtle tagged in Brazil captured in Gabon, Africa. Mar Turtle Newsl 87:11-12
Blumenthal JM, Austin TJ, Bothwell JB, Broderick AC and others (2009) Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef. Coral Reefs 28:55-65 Crossref
Börger L, Franconi N, De Michele G, Gantz A and others (2006) Effects of sampling regime on the mean and variance of home range size estimates. J Anim Ecol 75:1393-1405 Crossref
Briggs M, Alfaro-Shigueto J, Mangel JC, Acuña-Perales N, Pingo S, Jimenez A, Johnson AF (2024) Juvenile hawksbill turtle Eretmochelys imbricata movement patterns in Sechura Bay, Peru, assessed with satellite tracking. Mar Ecol Prog Ser 738:243-252 Crossref
Calenge C, Fortmann-Roe S (2023) Package ‘adehabitatHR’: home range estimation. R package version 0.4. 21. Link
Carlisle AB, Tickler D, Dale JJ, Ferretti F and others (2019) Estimating space use of mobile fishes in a large marine protected area with methodological considerations in acoustic array design. Front Mar Sci 6:256 Crossref
Chambault P, Dalleau M, Nicet J, Mouquet P, Ballorain K, Jean C (2020) Contrasted habitats and individual plasticity drive the fine scale movements of juvenile green turtles in coastal ecosystems. Mov Ecol 8:1 Crossref
Chassagneux A, Jean C, Bourjea J, Ciccione S (2013) Unraveling behavioral patterns of foraging hawksbill and green turtles using photo-identification. Mar Turtle Newsl 137:1-5
Chevis MG, Godley BJ, Lewis JP, Lewis JJ, Scales KL, Graham RT (2017) Movement patterns of juvenile hawksbill turtles Eretmochelys imbricata at a Caribbean coral atoll: Long-term tracking using passive acoustic telemetry. Endang Species Res 32:309-319 Crossref
Christiansen F, Esteban N, Mortimer JA, Dujon AM, Hays GC (2017) Diel and seasonal patterns in activity and home range size of green turtles on their foraging grounds revealed by extended Fastloc-GPS tracking. Mar Biol 164:10 Crossref
Conand F, Marsac F, Tessier E, Conand C (2008) A ten-year period of daily sea surface temperature at a coastal station in Reunion Island, Indian Ocean (July 1993-April 2004): patterns of variability and biological responses. West Indian Ocean J Mar Sci 6:1-16
Dujon AM, Lindstrom RT, Hays GC (2014) The accuracy of Fastloc-GPS locations and implications for animal tracking. Methods Ecol Evol 5:1162-1169 Crossref
Eckert KL, Bjorndal KA, Abreu-Grobois FA, Donnelly M (eds) (1999) Research and management techniques for the conservation of sea turtles. Publication No. 4. IUCN/SSC Marine Turtle Specialist Group, Washington, DC
Foster R, Kreitzman L (2011) Rhythms of life: the biological clocks that control the daily lives of every living thing. Profile Books, London
Godley BJ, Broderick AC, Glen F, Hays GC (2003) Post-nesting movements and submergence patterns of loggerhead marine turtles in the Mediterranean assessed by satellite tracking. J Exp Mar Biol Ecol 287:119-134 Crossref
Gredzens C, Marsh H, Fuentes MM, Limpus CJ, Shimada T, Hamann M (2014) Satellite tracking of sympatric marine megafauna can inform the biological basis for species co-management. PLOS ONE 9:e98944 Crossref
Hahsler M, Piekenbrock M, Doran D (2019) Dbscan: Fast density-based clustering with R. J Stat Softw 91:1-30 Crossref
Hamann M, Flavell F, Frazier J, Limpus CJ, Miller JD, Mortimer JA (2022) Assessment of the conservation status of the hawksbill turtle in the Indian Ocean and South-East Asia Region. CMS/IOSEA Marine Turtle MOU Secretariat Link
Hart KM, Sartain AR, Fujisaki I, Pratt HL Jr, Morley D, Feeley MW (2012) Home range, habitat use, and migrations of hawksbill turtles tracked from Dry Tortugas National Park, Florida, USA. Mar Ecol Prog Ser 457:193-207 Crossref
Hawkes LA, Tomás J, Revuelta O, León YM and others (2012) Migratory patterns in hawksbill turtles described by satellite tracking. Mar Ecol Prog Ser 461:223-232 Crossref
Hays GC, Hawkes LA (2018) Satellite tracking sea turtles: opportunities and challenges to address key questions. Front Mar Sci 5:432 Crossref
Hays GC, Luschi P, Papi F, del Seppia C, Marsh R (1999) Changes in behaviour during the inter-nesting period and post-nesting migration for Ascension Island green turtles. Mar Ecol Prog Ser 189:263-273 Crossref
Hays GC, Laloë J, Rattray A, Esteban N (2021) Why do Argos satellite tags stop relaying data? Ecol Evol 11:7093-7101 Crossref
Hays GC, Mortimer JA, Rattray A, Shimada T, Esteban N (2021) High accuracy tracking reveals how small conservation areas can protect marine megafauna. Ecol Appl 31:e02418 Crossref
Hays GC, Rattray A, Shimada T, Esteban N (2024) Individual variation in home-range across an ocean basin and links to habitat quality and management. J Appl Ecol 61:658-668 Crossref
Hochscheid S (2014) Why we mind sea turtles’ underwater business: a review on the study of diving behavior. J Exp Mar Biol Ecol 450:118-136 Crossref
Hochscheid S, Bentivegna F, Hamza A, Hays GC (2010) When surfacers do not dive: multiple significance of extended surface times in marine turtles. J Exp Biol 213:1328-1337 Crossref
Hooker SK, Gerber LR (2004) Marine reserves as a tool for ecosystem-based management: the potential importance of megafauna. Bioscience 54:27-39 Crossref
Hounslow JL, Fossette S, Byrnes EE, Whiting SD and others (2022) Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile. R Soc Open Sci 9:211860 Crossref
Jean C, Ciccione S, Talma E, Ballorain K, Bourjea J (2010) Photo-identification method for green and hawksbill turtles—first results from Reunion. Ind Ocean Turtle Newsl 11:8-12
Laforge A, Gaspar P, Barat A, Boyer JT and others (2023) Uncovering loggerhead (Caretta caretta) navigation strategy in the open ocean through the consideration of their diving behaviour. J R Soc Interface 20:20230383 Crossref
Laforge A, Ballorain K, Landes A, Bourjea J, Ciccione S, Jean C (2025) Tracking trends in foraging sea turtle aggregations at Reunion Island using aerial and photo-ID surveys (2008-2023). Endang Species Res 56:323-337 Crossref
Luschi P, Cerritelli G, Biondi A, Costanzi R and others (2025) Tireless travellers: sea turtles swim continuously during homing movements. Anim Behav 224:123203 Crossref
Makowski C, Seminoff JA, Salmon M (2006) Home range and habitat use of juvenile Atlantic green turtles (Chelonia mydas L.) on shallow reef habitats in Palm Beach, Florida, USA. Mar Biol 148:1167-1179 Crossref
Mansfield KL, Saba VS, Keinath JA, Musick JA (2009) Satellite tracking reveals a dichotomy in migration strategies among juvenile loggerhead turtles in the Northwest Atlantic. Mar Biol 156:2555-2570 Crossref
Marcovaldi M, Filippini A (1991) Trans-Atlantic movement by a juvenile hawksbill turtle. Mar Turtle Newsl 52:3
Martínez-Estévez L, Steller DL, Zilliacus KM, Amador JPC and others (2022) Foraging ecology of critically endangered Eastern Pacific hawksbill sea turtles (Eretmochelys imbricata) in the Gulf of California, Mexico. Mar Environ Res 174:105532 Crossref
Matley JK, Jossart J, Johansen L, Jobsis PD (2020) Environmental drivers of diving behavior and space-use of juvenile endangered Caribbean hawksbill sea turtles identified using acoustic telemetry. Mar Ecol Prog Ser 652:157-171 Crossref
Matley JK, Johansen LK, Klinard NV, Eanes ST, Jobsis PD (2021) Habitat selection and 3D space use partitioning of resident juvenile hawksbill sea turtles in a small Caribbean bay. Mar Biol 168:120 Crossref
Meylan PA, Meylan AB, Gray JA (2011) The ecology and migrations of sea turtles 8. Tests of the developmental habitat hypothesis. Bull Am Mus Nat Hist 2011:1-70 Crossref
Mortimer JA, Donnelly M (IUCN SSC Marine Turtle Specialist Group) (2008) Hawksbill turtle Eretmochelys imbricata. The IUCN Red List of Threatened Species 2008: e.T8005A12881238. dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T8005A12881238.en Crossref
Mortimer JA, Gerlach J, Summerton P (2010) Long distance migrations of hawksbills tagged as juveniles at Aldabra Atoll: confirmation from digital photography. Mar Turtle Newsl 129:11-13
Mortimer JA, Esteban N, Guzman AN, Hays GC (2020) Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago. Oryx 54:332-343 Crossref
Nivière M, Chambault P, Pérez T, Etienne D and others (2018) Identification of marine key areas across the Caribbean to ensure the conservation of the critically endangered hawksbill turtle. Biol Conserv 223:170-180 Crossref
Powell RA (2000) Animal home ranges and territories and home range estimators. In: Boitani L, Fuller TK (eds) Research techniques in animal ecology: controversies and consequences. Columbia University Press, New York, NY, p 65-110
R Core Team (2024) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. Link
Ropert M, Lazure P (2011) Projet HYDRORUN: Etat d’avancement du projet Ifremer-OIHYDRORUN. Première année (2010) Ifremer Océan Indien, Saint-Denis, La Réunion. Link
Selby TH, Hart KM, Smith BJ, Pollock CG, Hillis-Starr Z, Oli MK (2019) Juvenile hawksbill residency and habitat use within a Caribbean marine protected area. Endang Species Res 40:53-64 Crossref
Shimada T, Limpus CJ, Hamann M, Bell I, Esteban N, Groom R, Hays GC (2020) Fidelity to foraging sites after long migrations. J Anim Ecol 89:1008-1016 Crossref
Tanabe LK, Cochran JEM, Williams CT, Garzon F and others (2023) Case report: tracking data from foraging hawksbill turtles in the northern Red Sea. Anim Biotelem 11:1 Crossref
Thieurmel B, Elmarhraoui A (2019) Package ‘suncalc.’ R package version 05. CRAN.R-project.org/package=suncalc Link
van de Crommenacker J, Mortimer JA, Whiting A, Macrae I, Flores T, Whiting S (2022) Linkage between Cocos (Keeling) developmental habitat and hawksbill nesting beaches of Seychelles. Mar Turtle Newsl 165:25-27
van de Geer CH, Bourjea J, Broderick AC, Dalleau M and others (2022) Marine turtles of the African east coast: current knowledge and priorities for conservation and research. Endang Species Res 47:297-331 Crossref
van Zinnicq Bergmann MPM, Guttridge TL, Smukall MJ, Adams VM and others (2022) Using movement models and systematic conservation planning to inform marine protected area design for a multi-species predator community. Biol Conserv 266:109469 Crossref
von Brandis RG, Mortimer JA, Van De Geer C, Lea JS (2017) A long migratory record for a small post-pelagic hawksbill. Mar Turtle Newsl 152:13-15
Weber SB, Weber N, Godley BJ, Pelembe T, Stroud S, Williams N, Broderick AC (2017) Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles. J Mar Biol Assoc UK 97:813-820 Crossref
Whiting SD, Macrae I, Murray W, Thorn R, Flores T, Joynson-Hicks C, Hashim S (2010) Indian Ocean crossing by a juvenile hawksbill turtle. Mar Turtle Newsl 129:16-17
Wildermann NE, Gredzens C, Avens L, Barrios-Garrido HA and others (2018) Informing research priorities for immature sea turtles through expert elicitation. Endang Species Res 37:55-76 Crossref
Wood SN (2001) Mgcv: GAMs and generalized ridge regression for R. R News 1:20-25
Wood LD, Brunnick B, Milton SL (2017) Home range and movement patterns of subadult hawksbill sea turtles in Southeast Florida. J Herpetol 51:58-67 Crossref
Antoine Laforge (Corresponding Author)
- Centre d’Étude et de Découverte des Tortues Marines (CEDTM), 19 rue des Frangipaniers 97424 Saint Leu, La Réunion, France
Claire Jean (Co-author)
- Kelonia, l’observatoire des tortues marines, 46 rue du Général de Gaulle, 97436 Saint Leu, La Réunion, France
Stéphane Ciccione (Co-author)
- Kelonia, l’observatoire des tortues marines, 46 rue du Général de Gaulle, 97436 Saint Leu, La Réunion, France
Mayeul Dalleau (Co-author)
- Centre d’Étude et de Découverte des Tortues Marines (CEDTM), 19 rue des Frangipaniers 97424 Saint Leu, La Réunion, France
Katia Ballorain (Co-author)
- Centre d’Étude et de Découverte des Tortues Marines (CEDTM), 19 rue des Frangipaniers 97424 Saint Leu, La Réunion, France
Handling Editor:
Graeme Hays, Burwood, Victoria, Australia
Reviewers:
3 anonymous referees
Acknowledgements:
This study was conducted as part of the HOME-RUN project, funded by DEAL-Reunion, France Nation Verte, Fonds Vert Reunion 2023, and CCT-Reunion (2019-2023). We thank CMA CGM for their financial contribution toward data acquisition costs. Data collected prior to 2022 were obtained within the framework of PNA and TIMOI projects funded by the French State (DEAL-Reunion), European Union (INTERREG-V Indian Ocean). We express our gratitude to the Reunion Natural Marine Reserve and DEAL-Reunion for granting permission to conduct data collection in Reunion Island and within the Marine Reserve (DEAL/2017-01; DEAL/2014-03; DEAL/2014-06; DEAL/SEB/UBIO/2021-16; DEAL/SEB/UBIO/2023-90; DEAL/SEB/UBIO/2021-27). We are particularly grateful to Mathieu Barret, head of Kelonia’s care center, and Kevin Lay (Wildlife Computers) for their support in the data collection; the CEDTM and RMR-Kelonia teams, Maïté Smith and Anouck Baudouin for their field observation in the Hermitage lagoon; and Hendrik Sauvignet (Ocean-Obs), Ifremer and the diving club ‘Aquabulle’ for their contributions to fieldwork efforts. Finally, we also extend our sincere thanks to all contributors to the photo-identification programme and to those involved in photo management, including interns and staff, with special appreciation to Marie Lauret-Stepler (RMR-Kelonia), and to the people who retrieved the tags and returned them to us. We also thank the 3 anonymous reviewers whose thoughtful feedback helped significantly improve the paper.