ABSTRACT

Observed clutch frequency is the observed number of clutches deposited by a female turtle in a single nesting season. This value is generally biased compared to the true nest number because some clutches could have been missed by beach patrols. We constructed an analytical model to search for the distribution of observed clutch frequency according to 1) the distribution of the clutch number per female, 2) the probability of female capture on the beach, and 3) the probability that a female was an intraseasonal one-time nester. We used data from 1987 to 2003 collected on leatherbacks nesting on Yalimapo beach in French Guiana to test the power of the model. Whereas for 13 of the 16 years, the model produced estimates concurrent with the field data; for the other 3 years, there was no concordance, indicating a lack of power of the model. We describe a required level of capture effort on the beach that will be sufficient for the model to adequately describe clutch frequency across the nesting season. This level is the product of the proportion of the season monitored times the instantaneous probability of the presence and the detection for a particular female during 1 nesting event.

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