Fidelity and over-wintering of sea turtles

Abstract

While fidelity to breeding sites is well demonstrated in marine turtles, emerging knowledge of migratory routes and key foraging sites is of limited conservation value unless levels of fidelity can be established. We tracked green (Chelonia mydas, n=10) and loggerhead (Caretta caretta, n=10) turtles during their post-nesting migration from the island of Cyprus to their foraging grounds. After intervals of 2-5 years, five of these females were recaptured at the nesting beach and tracked for a second migration. All five used highly similar migratory routes to return to the same foraging and over-wintering areas. None of the females visited other foraging habitats over the study period (units lasted on average 305 days; maximum, 1356 days), moving only to deeper waters during the winter months where they demonstrated extremely long resting dives of up to 10.2h (the longest breath-holding dive recorded for a marine vertebrate). High levels of fidelity and the relatively discrete nature of the home ranges demonstrate that protection of key migratory pathways, foraging and over-wintering sites can serve as an important tool for the future conservation of marine turtles.

Movement patterns of marine turtles in the Mediterranean Sea: a review

“…Females breeding in Cyprus displayed much the same type A movement pattern, migrating towards more disparate foraging areas along the North African shelf or the Syrian coast or even remaining in Cyprus Broderick et al 2007) (Figure 1). In both cases, it is not to be excluded that other foraging sites for these populations may be discovered in the future, given that the number of tracked females is still quite low with respect to the number of females breeding in these rookeries (Schofield et al 2013).…”

“…Oruç 2001;Oruç et al 2011), but also in Greece and north Africa (e.g. Broderick et al 2007;Margaritoulis & Panagopoulou 2010). A limited number of individuals disperse as far as the Ionian, Adriatic and Tyrrhenian Seas (Lazar et al 2004;Bentivegna et al 2011).…”

A critical review of the Mediterranean sea turtle rescue network: a web looking for a weaver

“…The Pelagie Islands, for example, are a core foraging ground here (Casale et al 2012b). Individuals from the key Mediterranean turtle rookeries, i.e., western Greece, Crete, and Cyprus, frequent these central Mediterranean feeding grounds (Margaritoulis et al 2003, Broderick et al 2007, Casale et al 2008a, Zbinden et al 2008. Other important neritic foraging areas are off southeastern Turkey, the Egyptian coast (Gerosa and Casale 1999), and the Spanish coast (Gómez de Segura et al 2006).…”

“…The North African coast is apparently an important migratory pathway for loggerheads across the Mediterranean (Broderick et al 2007, Casale et al 2012b. Seasonal movements include southbound emigration movements from the northern Adriatic , Zbinden et al 2008, Zbinden et al 2011) and movements of juveniles in the western Mediterranean (Cardona et al 2009).…”

“…grounds (Broderick et al 2007). Individuals of the Mediterranean RMU ) range throughout the basin; Atlantic transients visit foraging habitats in the western Mediterranean.…”