TESTING MODELS OF FEMALE REPRODUCTIVE MIGRATORY BEHAVIOR AND POPULATION-STRUCTURE IN THE CARIBBEAN HAWKSBILL TURTLE, ERETMOCHELYS IMBRICATA, WITH MTDNA SEQUENCES

Information on the reproductive behaviour and population structure of female hawksbill turtles, Eretmochelys imbricata, is necessary to defi ne conservation priorities for this highly endangered species. Two hyp otheses to explain female nest site choice, natal homing and social fa cilitation, were tested by analysing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and west ern Atlantic. Under the social facilitation model, newly mature female s follow older females to a nesting location, and subsequently use thi s site for future nesting. This model generates an expectation that fe male lineages will be homogenized among regional nesting colonies. Con trary to expectations of the social facilitation model, mtDNA lineages were highly structured among western Atlantic nesting colonies. These analyses identified at least 6 female breeding stocks in the Caribbea n and western Atlantic and support a natal homing model for recruitmen t of breeding females. Reproductive populations are effectively isolat ed over ecological time scales, and recovery plans for this species sh ould include protection at the level of individual nesting colonies.