Skip to main content
    • Aa
    • Aa

The value of long-term, community-based monitoring of marine turtle nesting: a study in the Lamu archipelago, Kenya

  • Mike I. Olendo (a1), Gladys M. Okemwa (a2), Cosmas N. Munga (a3), Lilian K. Mulupi (a1), Lily D. Mwasi (a1), Hassan B. Mohamed (a1), Mxolisi Sibanda (a4) and Harrison O. Ong'anda (a2)...

Monitoring of nesting beaches is often the only feasible and low-cost approach for assessing sea turtle populations. We investigated spatio-temporal patterns of sea turtle nesting activity monitored over 17 successive years in the Lamu archipelago, Kenya. Community-based patrols were conducted on 26 stretches of beach clustered in five major locations. A total of 2,021 nests were recorded: 1,971 (97.5%) green turtle Chelonia mydas nests, 31 (1.5%) hawksbill Eretmochelys imbricata nests, 8 (0.4%) olive ridley Lepidochelys olivacea nests and 11 (0.5%) unidentified nests. Nesting occurred year-round, increasing during March–July, when 74% of nests were recorded. A stable trend in mean annual nesting densities was observed in all locations. Mean clutch sizes were 117.7 ± SE 1 eggs (range 20–189) for green turtles, 103 ± SE 6 eggs (range 37–150) for hawksbill turtles, and 103 ± SE 6 eggs (range 80–133) for olive ridley turtles. Curved carapace length for green turtles was 65–125 cm, and mean annual incubation duration was 55.5 ± SE 0.05 days. The mean incubation duration for green turtle nests differed significantly between months and seasons but not locations. The hatching success (pooled data) was 81.3% (n = 1,841) and was higher for in situ nests (81.0 ± SE 1.5%) compared to relocated nests (77.8 ± SE 1.4%). The results highlight the important contribution of community-based monitoring in Kenya to sustaining the sea turtle populations of the Western Indian Ocean region.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle.

      Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      The value of long-term, community-based monitoring of marine turtle nesting: a study in the Lamu archipelago, Kenya
      Available formats
      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about sending content to Dropbox.

      The value of long-term, community-based monitoring of marine turtle nesting: a study in the Lamu archipelago, Kenya
      Available formats
      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about sending content to Google Drive.

      The value of long-term, community-based monitoring of marine turtle nesting: a study in the Lamu archipelago, Kenya
      Available formats
Corresponding author
(Corresponding author) Email
Hide All

Supplementary material for this article is available at

Hide All
A.A. Aguirre & P.L. Lutz (2004) Marine turtles as sentinels of ecosystem health: is fibropapillomatosis an indicator? EcoHealth, 1, 275283.

Z.C. Allen , N.J. Shah , A. Grant , G.D. Derand & D.J. Bell (2010) Hawksbill turtle monitoring in Cousin Island Special Reserve, Seychelles: an eight-fold increase in annual nesting numbers. Endangered Species Research, 11, 195200.

A. Almeida , L.M. Moreira , S.C. Bruno , J.C.A. Thomé , A.S. Martins , A.B. Bolten & K.A. Bjorndal (2011) Green turtle nesting on Trindade Island, Brazil: abundance, trends, and biometrics. Endangered Species Research, 14, 193201.

R. Anastácio , C. Santos , C. Lopes , H. Moreira , L. Souto , J. Ferrão (2014) Reproductive biology and genetic diversity of the green turtle (Chelonia mydas) in Vamizi island, Mozambique. SpringerPlus, 3, 540.

R.L. Antworth , D.A. Pike & J.C. Stiner (2006) Nesting ecology, current status, and conservation of sea turtles on an uninhabited beach in Florida, USA. Biological Conservation, 130, 1015.

K.A. Bjorndal , J. Parsons , W. Mustin & A.B. Bolten (2013) Threshold to maturity in a long-lived reptile: interactions of age, size, and growth. Marine Biology, 160, 607616.

J. Bourjea , M. Dalleau , S. Derville , F. Beudard , C. Marmoex , A. M'Soili (2015) Seasonality, abundance and fifteen-year trend in green turtle nesting activity in Itsamia, Moheli Comoros. Endangered Species Research, 27, 265276.

J. Bourjea , J. Frappier , M. Quillard , S. Ciccione , D. Roos , G. Hughes & H. Grizel (2007) Mayotte Island: another important green turtle nesting site in the southwest Indian Ocean. Endangered Species Research, 3, 273282.

A.C. Broderick , F. Glen , B.J. Godley & G.C. Hays (2003) Variation in reproductive output of marine turtles. Journal of Experimental Marine Biology and Ecology, 288, 95109.

A.C. Broderick & B.J. Godley (1996) Population and nesting ecology of the green turtle, Chelonia mydas, and the loggerhead turtle, Caretta caretta, in northern Cyprus. Zoology in the Middle East, 13, 2746.

A.C. Broderick , B.J. Godley & G.C. Hays (2001) Trophic status drives interannual variability in nesting numbers of marine turtles. Proceedings of the Royal Society of London B, 268, 14811487.

A.C. Broderick , B.J. Godley , S. Reece & J.R. Downie (2000) Incubation periods and sex ratios of green turtles: highly female biased hatchling production in the eastern Mediterranean. Marine Ecology Progress Series, 202, 273281.

H.R. Bustard & P. Greenham (1968) Physical and chemical factors affecting hatching in the green sea turtle Chelonia mydas (L.). Ecology, 49, 269276.

M. Chaloupka (2001) Historical trends, seasonality and spatial synchrony in green sea turtle egg production. Biological Conservation, 101, 263279.

M. Dalleau , S. Ciccione , J.A. Mortimer , J. Garnier , S. Benhamou & J. Bourjea (2012) Nesting phenology of marine turtles: insights from a regional comparative analysis on green turtle (Chelonia mydas). PLoS ONE, 7(10), e46920.

S. Derville , C. Jean , M. Dalleau , J.Y. Le Gall , S. Ciccione & J. Bourjea (2015) Long-term monitoring of green turtle nesting on Tromelin Island demonstrates stable reproduction and population parameters. Chelonian Conservation and Biology, 14, 1120.

M.A. Ditmer & S.P. Stapleton (2012) Factors affecting hatch success of hawksbill sea turtles on Long Island, Antigua, West Indies. PLoS ONE, 7(7), e38472.

G.C.A. Duineveld , P.A.W.J. De Wilde , E.M. Berghuis , A. Kok , T. Tahey & J. Kromkamp (1997) Benthic respiration and standing stock on two contrasting continental margins in the western Indian Ocean: the Yemen-Somali upwelling region and the margin off Kenya. Deep Sea Research Part II: Topical Studies in Oceanography, 44, 12931317.

K.L. Eckert & S.A. Eckert (1990) Embryo mortality and hatch success in in situ and translocated leatherback sea turtle Dermochelys coriacea eggs. Biological Conservation, 53, 3746.

J. Frazier (1975) Marine turtles of the Western Indian Ocean. Oryx, 13, 164175.

M.M.P.B. Fuentes , M.R. Fish & J.A. Maynard (2012) Management strategies to mitigate the impacts of climate change on sea turtles’ terrestrial reproductive phase. Mitigation and Adaptation Strategies for Global Change, 17, 5163.

A. Garcia , G. Ceballos & R. Adaya (2003) Intensive beach management as an improved sea turtle conservation strategy in Mexico. Biological Conservation, 111, 253261.

J. Garnier , N. Hill , A. Guissamulo , I. Silva , M. Witt & B. Godley (2012) Status and community-based conservation of marine turtles in the northern Querimbas Islands (Mozambique). Oryx, 46, 359367.

F. Glen & N. Mrosovsky (2004) Antigua revisited: the impact of climate change on sand and nest temperatures at a hawksbill turtle (Eretmochelys imbricata) nesting beach. Global Change Biology, 10, 20362045.

G.C. Hays (2000) The implications of variable remigration intervals for the assessment of population size in marine turtles. Journal of Theoretical Biology, 206, 221227.

F. Humber , B.J. Godley , T. Nicolas , O. Raynaud , F. Pichon & A. Broderick (2017) Placing Madagascar's marine turtle populations in a regional context using community-based monitoring. Oryx, 51, 542553.

M. Lauret-Stepler , J. Bourjea , D. Roos , D. Pelletier , P.G. Ryan , S. Ciccione & H. Grizel (2007) Reproductive seasonality and trend of Chelonia mydas in the SW Indian Ocean: a 20 yr study based on track counts. Endangered Species Research, 3, 217227.

S.J. McCauley & K.A. Bjorndal (1999) Conservation implications of dietary dilution from debris ingestion: sublethal effects in post-hatchling loggerhead sea turtles. Conservation Biology, 13, 925929.

T.R. McClanahan (1988) Seasonality in East Africa's coastal waters. Marine Ecology Progress Series, 44, 191199.

J.A. Mortimer (1990) The influence of beach sand characteristics on the nesting behavior and clutch survival of green turtles (Chelonia mydas). Copeia, 1990, 802817.

J.A. Mortimer (2012) Seasonality of green turtle (Chelonia mydas) reproduction at Aldabra Atoll, Seychelles (1980–2011) in the regional context of the Western Indian Ocean. Chelonian Conservation and Biology, 11, 170181.

J.A. Mortimer & A. Carr (1987) Reproduction and migrations of the Ascension Island green turtle (Chelonia mydas). Copeia, 1987, 103113.

J.A. Mortimer & K.M. Portier (1989) Reproductive homing and inter-nesting behavior of the green turtle (Chelonia mydas) at Ascension Island, South Atlantic Ocean. Copeia, 1989, 962977.

J.A. Mortimer , R.G. von Brandis , A. Liljevik , R. Chapman & J. Collie (2011) Fall and rise of nesting green turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: positive response to four decades of protection (1968–2008). Chelonian Conservation and Biology, 10, 165176.

N. Mrosovsky & C.L. Yntema (1980) Temperature dependence of sexual differentiation in sea turtles: implications for conservation practices. Biological Conservation, 18, 271280.

R. Nel , A.E. Punt & G.R. Hughes (2013) Are coastal protected areas always effective in achieving population recovery for nesting sea turtles? PLoS ONE, 8(5), e63525.

S.E. Piacenza , G.H. Balazs , S.K. Hargrove , P.M. Richards & S.S. Heppell (2016) Trends and variability in demographic indicators of a recovering population of green sea turtles Chelonia mydas . Endangered Species Research, 31, 103117.

K.J. Pintus , B.J. Godley , A. McGowan & A.C. Broderick (2009) Impact of clutch relocation on green turtle offspring. The Journal of Wildlife Management, 73, 11511157.

O. Revuelta , Y.M. León , A.C. Broderick , P. Feliz , B.J. Godley , J.A. Balbuena (2015) Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic. Oryx, 49, 677686.

F.A. Schott & J.P. McCreary Jr (2001) The monsoon circulation of the Indian Ocean. Progress in Oceanography, 51, 1123.

T. Spencer , A.S. Laughton & N.C. Flemming (2005) Variability, interaction and change in the atmosphere–ocean–ecology system of the Western Indian Ocean. Philosophical Transactions of the Royal Society A, 363, 313.

J. Tuttle & D. Rostal (2010) Effects of nest relocation on nest temperature and embryonic development of loggerhead sea turtles (Caretta caretta). Chelonian Conservation and Biology, 9, 17.

J. van Buskirk & L.B. Crowder (1994) Life-history variation in marine turtles. Copeia, 1994, 6681.

B.P. Wallace , A.D. DiMatteo , A.B. Bolten , M.Y. Chaloupka , B.J. Hutchinson , F.A. Abreu-Grobois (2011) Global conservation priorities for marine turtles. PLoS ONE, 6(9), e24510.

J.F. Weishampel , D.A. Bagley , L.M. Ehrhart & B.L. Rodenbeck (2003) Spatiotemporal patterns of annual sea turtle nesting behaviors along an East Central Florida beach. Biological Conservation, 110, 295303.

D.W. Wood & K.A. Bjorndal (2000) Relation of temperature, moisture, salinity, and slope to nest site selection in loggerhead sea turtles. Copeia, 2000, 119128.

V.E. Wood (1986) Breeding success of hawksbill turtles Eretmochelys imbricata at Cousin Island, Seychelles, and the implications for their conservation. Biological Conservation, 37, 321332.

R. Xavier , A. Barata , L.P. Cortez , N. Queiroz & E. Cuevas (2006) Hawksbill turtle (Eretmochelys imbricata Linnaeus 1766) and green turtle (Chelonia mydas Linnaeus 1754) nesting activity (2002–2004) at El Cuyo beach, Mexico. Amphibia-Reptilia, 27, 539547.

P. Zárate , K.A. Bjorndal , M. Parra , P.H. Dutton , J.A. Seminoff & A.B. Bolten (2013) Hatching and emergence success in green turtle Chelonia mydas nests in the Galápagos Islands. Aquatic Biology, 19, 217229.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0030-6053
  • EISSN: 1365-3008
  • URL: /core/journals/oryx
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Type Description Title
Supplementary Materials

Olendo supplementary material
Tables S1-S3

 PDF (308 KB)
308 KB


Altmetric attention score

Full text views

Total number of HTML views: 3
Total number of PDF views: 85 *
Loading metrics...

Abstract views

Total abstract views: 449 *
Loading metrics...

* Views captured on Cambridge Core between 1st August 2017 - 26th September 2017. This data will be updated every 24 hours.