The Herpetological Journal

pp. 23-28
Authors: Kumar, R. Suresh; John, Sajan; Sivakumar, K. & Choudhury, Binod C.

Abstract: The olive ridley sea turtle Lepidochelys olivacea is known for its unusual behaviour of locally nesting en masse in the eastern Pacific and the east coast of India, leading to difficulties in quantifying population size. In the present study we estimate nesting population sizes in the state of Orissa, taking average egg laying or oviposition duration (OD) into account. We observed 182 and 263 nesting turtles during mass nesting events of 2009 and 2010 to estimate ODs of 19.8±5.8 and 17.2±5.9 minutes, respectively. Clutch size averaged 123.1±10.5 for 2009 and 124.3±18.6 for 2010, which is 10 to 20% more than the global clutch size of 100–110 eggs, and appears to have resulted in a longer OD than previously assumed. Using the average OD from this study, 172,407±7509 and 134,478±6204 turtles were estimated to have nested during 2009 and 2010 respectively, contrasting the 200,000–250,000 turtles reported by the Forest Department. Our results suggest that a minimum of 150 egg laying turtles across each night of the mass nesting period is required to be observed for an accurate quantification of OD.

Keywords: OVIPOSITION DURATION, CLUTCH SIZE, ARRIBADA, LEPIDOCHELYS OLIVACEA, OLIVE RIDLEY TURTLE, POPULATION ESTIMATION