Transient nocturnal site fidelity in juvenile green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles on the shallow nearshore coral reefs of South Caicos, Turks and Caicos Islands

Abstract

Opportunistic nocturnal catch-and-release turtle surveys were conducted on three nearshore, shallow coral reefs that fringe the main navigation channel to Cockburn Harbour, South Caicos, between 2005 and 2015. A total of 117 captures were made, representing 73 individual turtles (32 green, 41 hawksbill). Almost half of the green turtles were recaptured on at least one occasion, with a maximum time at liberty of 574 days (median = 94 days). Only 20% of hawksbill turtles were recaptured, with a maximum time at liberty of 587 days (median = 120 days). These data suggest that the study sites are utilised by a combination of transient visitors and short to medium-term resident turtles. However, no evidence of long-term nocturnal site fidelity was found. The size ranges observed in both species indicate that all turtles were immature, and the minimum sizes are consistent with previously reported settlement sizes from the region. Despite the lack of long-term fidelity, turtles were regularly encountered over the course of the study, indicating that these reefs are an important nocturnal refugium for local juvenile turtles in general.