Impact of density‐dependent nest destruction on emergence success of Guianan leatherback turtles (Dermochelys coriacea)

Abstract

To assess the impact of nest covering on a leatherback turtle Dermochelys coriacea nesting beach in French Guiana, we used field study data and a modelling approach. Field results showed that the covering of a pre-existing nest by a new one causes the destruction of the older nest under some conditions of time and covering area, and almost always causes the destruction of the new nest. We then used field results to parameterize a theoretical model of the nesting beach. This allowed us to obtain a 'critical carrying capacity for the beach': the number of nests deposited for which the number of successful nests is maximum; when this number increases, the number of successful nests decreases. With these results, we then concluded that density-dependent nest destruction plays a role in the functioning of the nesting beach. These results are essential for our understanding of nest-site selection at the scale of the beach and its consequences.

Estimating carrying capacity at the green turtle nesting beach of East Island, French Frigate Shoals

“…Females have been observed to destroy incubating nests during their nesting process on East Island (Balazs 1980). When a turtle crawls up a beach to nest, she clears the sand around her with her flippers creating a body pit, and then excavates the nest chamber, deposits her eggs, and covers up and camouflages the nest; at high nest densities nearby incubating nests are often destroyed by a nesting turtle (Girondot et al 2002, Caut et al 2006, Tiwari et al 2006. As destroyed eggs accumulate in the sand, increased microbial activity may increase mortality within incubating nests (Cornelius et al 1991, Marcovaldi et al 1999, Phillott & Parmenter 2001.…”

Effect of tidal overwash on the embryonic development of leatherback turtles in French Guiana

“…This threat is especially true for narrow beaches, such as Yalimapo, on which nests are already located close to the high-tide line, thus exposing them to a greater risk of nest overlap and tidal inundation. Reduction of the size of nesting beaches has implications for reproduction success, especially in major nesting sites such as Yalimapo where density-dependent effects have already had a detrimental effect on nest development (Caut et al, 2006b).…”

“…When eggshells were fragmented, pieces were grouped together to represent one egg. The use of shell fragments to estimate hatching success had been previously validated in an open-air hatchery study (Caut et al, 2006b). …”

Trends and variability in demographic indicators of a recovering population of green sea turtles Chelonia mydas

“…However, we must first understand how DIs and their variability are linked to abundance. If a DI displays a trend in response to decline or recovery, then the DI can be linked to population abundance, and once general relationships are established, a DI could be used as a population status indicator in the absence of a population index (Bjorndal et al 2000, Saether & Bakke 2000, Caut et al 2006, Hutchings et al 2012. Conversely, if a DI has high interannual variability but no significant trend, the variability itself could affect population growth, abundance, and recovery rates, and is valuable information in itself (Mazaris & Matsinos 2006, Bjorndal et al 2010.…”