Elsevier

Animal Behaviour

Volume 163, May 2020, Pages 85-94
Animal Behaviour

Mass-nesting events in olive ridley sea turtles: environmental predictors of timing and size

https://doi.org/10.1016/j.anbehav.2020.03.002Get rights and content

Highlights

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    We analysed 10 years of olive ridley sea turtle mass-nesting data.

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    We used 12 variables as predictors in a statistical model-averaging approach.

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    The onset of nesting coincided predominantly with the last-quarter moon.

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    Some variables improved predictions of timing and number of turtles participating.

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    No single variable infallibly predicted the timing or size of mass-nesting events.

During the mass nesting of olive ridley sea turtles, Lepidochelys olivacea, thousands of adult females aggregate offshore, then emerge from the ocean together to lay their eggs along small, specific stretches of coastline. Little is known about the mechanisms that underlie synchronization of mass nesting. As a first step towards identifying environmental variables that control or affect the timing of mass-nesting events, we analysed 10 years of nesting data from Ostional, Costa Rica, a Pacific beach where mass-nesting events occur throughout the year. The onset of mass nesting was not uniformly distributed across lunar phase, with mass nesting occurring predominantly near last-quarter moon. Statistical models were developed to investigate whether environmental variables could be used to predict the timing and size of mass-nesting events. Predictions of the onset of nesting were improved by considering lunar phase and the time since the previous mass-nesting event as well as several oceanographic variables. Predictions of the number of turtles participating in nesting events were improved by considering salinity, relative humidity and nearshore current velocity, three parameters related to weather patterns and rainfall. Overall, the results imply that mass-nesting events at Ostional tend to occur near last-quarter moon but do not follow an invariant lunar or seasonal pattern. Instead, the results suggest that physiological and environmental factors interact to influence mass-nesting events, with no single environmental variable serving as an infallible predictor of either timing or size.

Section snippets

Study Site

The Ostional National Wildlife Refuge is located on the northern Pacific peninsula of Costa Rica (Fig. 1). Within the Refuge, Ostional Beach comprises approximately 4 km of coastline. For research and monitoring purposes, the beach is divided into 50 m sectors numbered from north to south. The data used in this study were collected as part of a long-term monitoring project authorized under Costa Rica permits (MINAE-SINAC-ACT, ACT-OR-DR-033-17).

Mass-nesting Census Data

We analysed approximately 10 years (July

Patterns of Mass-nesting Behaviour

During the 10-year period encompassed by the data set, a mean of 11 ± 0.2 (mean ± SEM) mass-nesting events occurred each year. Arribadas had a mean duration of 3 ± 0.2 days and a mean interval of 34 ± 1.4 days between events. The interval between events was longer in the dry season (37 ± 2.3 days) than in the rainy season (32 ± 1.8 days; t test: t1 = -1.77, N = 103 intervals, P = 0.040). During the rainy season, two events occurred within a single month on nine occasions; this never occurred during the dry

Discussion

Several authors have speculated that environmental cues such as onshore winds, precipitation, lunar phase and/or tidal cycle either trigger or strongly influence the timing of mass-nesting events in ridley turtles (Carr, 1967, Hughes and Richard, 1974, Jiménez-Quiroz et al., 2005, Plotkin et al., 1997, Pritchard, 1969). These suggestions have arisen largely from anecdotal observations and short-term studies spanning periods of a few months. By contrast, our study of mass-nesting events over a

Funding

This work was supported by a National Science Foundation Graduate Research Fellowship Program (to V.S.B.) and a National Science Foundation grant (IOS-1456923) to K.J.L.

Declaration of Competing Interest

We declare no financial or competing interests.

Acknowledgments

We thank the Área de Conservación Tempisque regional sea turtle project for providing the data used in this study, which was collected as part of a larger investigation authorized under Costa Rica permits (MINAE-SINAC-ACT, ACT-OR-DR-033-17). We are grateful to G. Bran, Y. Arguello, J. Quiros, J. Pablo, Y. Cedeño, L. Brenes and all of the research assistants and volunteers at the Ostional National Wildlife Refuge for making this research possible. We thank R. Johnson for collecting and providing

References (73)

  • E. Batschelet

    Circular statistics in biology

    (1981)
  • S.C. Beavers et al.

    Movements and dive behavior of a male sea turtle (Lepidochelys olivacea) in the Eastern Tropical Pacific

    Journal of Herpetology

    (1996)
  • J. Bernardo et al.

    An evolutionary perspective on the arribada phenomenon and reproductive behavioral polymorphism of olive ridley sea turtles (Lepidochelys olivacea)

  • B.M. Bolker et al.

    Generalized linear mixed models: A practical guide for ecology and evolution

    Trends in Ecology & Evolution

    (2008)
  • A. Carr

    So excellent a fishe

    (1967)
  • E. Coria-Monter et al.

    The relationship between the massive nesting of the olive ridley sea turtle (Lepidochelys olivacea) and the local physical environment at La Escobilla, Oaxaca, Mexico, during 2005

    Hidrobiologica

    (2017)
  • S.E. Cornelius et al.

    Post-nesting movements of female olive ridley turtles tagged in Costa Rica

    Vida Silvestre Neotropical

    (1986)
  • C.E. Eckrich et al.

    Solitary versus arribada nesting in the olive ridley sea turtles (Lepidochelys olivacea): A test of the predator-satiation hypothesis

    Herpetologica

    (1995)
  • T. Eguchi et al.

    At-sea density and abundance estimates of the olive ridley turtle Lepidochelys olivacea in the eastern tropical Pacific

    Endangered Species Research

    (2007)
  • A.K. English et al.

    Reassessing the determinants of breeding synchrony in ungulates

    PloS One

    (2012)
  • C.R. Ferrara et al.

    Sound communication and social behavior in an Amazonian river turtle (Podocnemis expansa)

    Herpetologica

    (2014)
  • D.A. Fournier et al.

    AD Model Builder: Using automatic differentiation for statistical inference of highly parameterized complex nonlinear models

    Optimization Methods and Software

    (2012)
  • M. Fukushiro et al.

    Lunar phase-dependent expression of Cryptochrome and a photoperiodic mechanism for lunar phase-recognition in a reef fish, goldlined spinefoot

    PloS One

    (2011)
  • C. Gates et al.

    Estimating arribada size using a modified instantaneous count procedure

    Journal of Agricultural, Biological, and Environmental Statistics

    (1996)
  • C.E. Grueber et al.

    Multimodel inference in ecology and evolution: Challenges and solutions

    Journal of Evolutionary Biology

    (2011)
  • Ö. Güçlü et al.

    Mycoflora identified from loggerhead turtle (Caretta caretta) egg shells and nest sand at Fethiye beach, Turkey

    African Journal of Microbiology Research

    (2010)
  • S.M. Henson et al.

    Socially induced synchronization of every-other-day egg laying in a seabird colony

    Auk: Ornithological Advances

    (2010)
  • M. Hirschfeld et al.

    Variable reproductive strategies of an African savanna frog, Phrynomantis microps (Amphibia, Anura, Microhylidae)

    Journal of Tropical Ecology

    (2011)
  • H. Hirth

    Some aspects of the nesting behavior and reproductive biology of sea turtles

    American Zoologist

    (1980)
  • D.A. Hughes et al.

    The nesting of the Pacific ridley turtle Lepidochelys olivacea on Playa Nancite, Costa Rica

    Marine Biology

    (1974)
  • C. Jackson

    Flexsurv: A platform for parametric survival modeling in R

    Journal of Statistical Software

    (2016)
  • M.C. Jiménez-Quiroz et al.

    Time-series analyses of the relationship between nesting frequency of the Kemp's ridley sea turtle and meteorological conditions

    Chelonian Conservation and Biology

    (2005)
  • P.L. Jokiel et al.

    Night irradiance and synchronization of lunar release of planulae larvae in the reef coral Pocillopora damicornis

    Marine Biology

    (1985)
  • H. Kalb

    Behavior and physiology of solitary and arribada nesting olive ridley sea turtles (Lepidochelys olivacea) during the internesting period

    (1999)
  • P.J. Kelly et al.

    Survival analysis for recurrent event data: An application to childhood infectious diseases

    Statistics in Medicine

    (2000)
  • I. Koizumi et al.

    Socially induced reproductive synchrony in a salmonid: An approximate Bayesian computation approach

    Behavioral Ecology

    (2016)

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