Julia A. Horrocks

Testing models of female reproductive migratory behaviour 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 define conservation priorities for this highly endangered species. Two hypotheses to explain female nest site choice, natal homing and social facilitation, were tested by analysing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and western Atlantic. Under the social facilitation model, newly mature females follow older females to a nesting location, and subsequently use this site for future nesting. This model generates an expectation that female lineages will be homogenized among regional nesting colonies. Contrary 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 Caribbean and western Atlantic and support a natal homing model for recruitment of breeding females. Reproductive populations are effectively isolated over ecological time scales, and recovery plans for this species should include protection at the level of individual nesting colonies.

Re-examination of Population Structure and Phylogeography of Hawksbill Turtles in the Wider Caribbean Using Longer mtDNA Sequences

Management of the critically endangered hawksbill turtle in the Wider Caribbean (WC) has been hampered by knowledge gaps regarding stock structure. We carried out a comprehensive stock structure re-assessment of 11 WC hawksbill rookeries using longer mtDNA sequences, larger sample sizes (N = 647), and additional rookeries compared to previous surveys. Additional variation detected by 740 bp sequences between populations allowed us to differentiate populations such as Barbados-Windward and Guadeloupe (F (st) = 0.683, P < 0.05) that appeared genetically indistinguishable based on shorter 380 bp sequences. POWSIM analysis showed that longer sequences improved power to detect population structure and that when N < 30, increasing the variation detected was as effective in increasing power as increasing sample size. Geographic patterns of genetic variation suggest a model of periodic long-distance colonization coupled with region-wide dispersal and subsequent secondary contact within the WC. Mismatch analysis results for individual clades suggest a general population expansion in the WC following a historic bottleneck about 100 000-300 000 years ago. We estimated an effective female population size (N (ef)) of 6000-9000 for the WC, similar to the current estimated numbers of breeding females, highlighting the importance of these regional rookeries to maintaining genetic diversity in hawksbills. Our results provide a basis for standardizing future work to 740 bp sequence reads and establish a more complete baseline for determining stock boundaries in this migratory marine species. Finally, our findings illustrate the value of maintaining an archive of specimens for re-analysis as new markers become available.

Population subdivision in hawksbill turtles nesting on Barbados, West Indies, determined from mitochondrial DNA control region sequences

A new mitochondrial DNA control region survey of the Barbados hawksbill nesting population was undertaken using larger sample sizes, reanalysis of previously reported samples, and new primers that increase the fragment length sequenced. This work revealed that haplotypes originally identified as endemic to Barbados were misread sequences. Genetic variants and a geographic subdivision on a finer scale than has previously been recorded for sea turtles were identified between the Barbados leeward and windward coasts, indicating the need for sampling at multiple sites to reveal comprehensive genetic variation at national scales. Using the updated haplotype profiles to re-estimate Barbados’ contribution to Caribbean hawksbill foraging grounds indicated a presence several-fold larger than previously calculated; a result congruent with the breeding population being one of the largest in the region.

Predicting species interactions from edge responses: mongoose predation on hawksbill sea turtle nests in fragmented beach habitat

Because species respond differently to habitat boundaries and spatial overlap affects encounter rates, edge responses should be strong determinants of spatial patterns of species interactions. In the Caribbean, mongooses (Herpestes javanicus) prey on hawksbill sea turtle (Eretmochelys imbricata) eggs. Turtles nest in both open sand and vegetation patches, with a peak in nest abundance near the boundary between the two microhabitats; mongooses rarely leave vegetation. Using both artificial nests and hawksbill nesting data, we examined how the edge responses of these species predict the spatial patterns of nest mortality. Predation risk was strongly related to mongoose abundance but was not affected by nest density or habitat type. The product of predator and prey edge response functions accurately described the observed pattern of total prey mortality. Hawksbill preference for vegetation edge becomes an ecological trap in the presence of mongooses. This is the first study to predict patterns of predation directly from continuous edge response functions of interacting species, establishing a link between models of edge response and species interactions.

Conservation Of Insular Herpetofaunas In The West Indies

There are approximately 700 species of amphibians and reptiles that have been described from the West Indies, here defined as excluding Trinidad and Tobago which are adjacent to South America and have continental faunas. This includes approximately 180 amphibians and 520 reptiles. The conservation status of only the amphibians has been assessed comprehensively, and 84% of those species are considered threatened. This chapter provides brief overview of the origin and evolution of the West Indian herpetofauna. This is followed by a discussion of two aspects vital to its conservation: stopping deforestation and facilitating systematic research. For some species, especially large reptiles, it has been claimed that introduced predators have had a greater negative impact than habitat alteration. Although this probably is true in some instances, the point made here is that habitat destruction-in particular, deforestation-is the major and primary threat to the survival of most species. Keywords:amphibians; deforestation; habitat alteration; reptiles; West Indian herpetofauna

International Movements of Adult Female Hawksbill Turtles (Eretmochelys imbricata): First Results from the Caribbean's Marine Turtle Tagging Centre

Abstract Effective management of migratory sea turtles requires informed and sustained collaboration among range states. The primary objective of the Wider Caribbean Sea Turtle Conservation Networks regional Marine Turtle Tagging Centre at the University of the West Indies, Barbados, has been to encourage and enable such collaboration, uniting otherwise isolated sea turtle tagging programs to benefit from information on the geographic range of sea turtles tagged in one country and captured, sighted, or stranded in another country. We present the first summary of information gleaned from international tag returns of adult female hawksbill sea turtles (Eretmochelys imbricata) marked with Marine Turtle Tagging Centre tags. Twenty-one sea turtle projects in 19 countries and overseas territories received Inconel 1005–681 tags from the Marine Turtle Tagging Centre between January 2002 and June 2009, and 12 of these projects have reported tagging adult female hawksbills, for a combined total of 2261 tagged individuals. Sixty-three of these individuals (2.8%), sighted at least once in another country since being tagged, have been reported to the Marine Turtle Tagging Centre; the majority of them (96.8%) were originally tagged while they were nesting in Barbados. Based on minimum straight-line distance traveled, the point of capture averaged 343.9 ± 69.7 km standard error (SE), (median 175 km) from the nesting beach. The average number of days between tagging and the first recapture was 835 ± 67.9 days SE, median 860 days). Although the majority of returns came from within a few hundred kilometers of the tagging site, tagged animals often passed through multiple exclusive economic zones and were exposed to conflicting management regimes, which include legal and illegal sea turtle fisheries. The shallow continental shelf off the coasts of Nicaragua and Honduras was confirmed as a foraging ground for Eastern Caribbean hawksbills.

EFFECTS OF "SWIM WITH THE TURTLES" TOURIST ATTRACTIONS ON GREEN SEA TURTLE (CHELONIA MYDAS) HEALTH IN BARBADOS, WEST INDIES

Abstract Along the West Coast of Barbados a unique relationship has developed between endangered green sea turtles (Chelonia mydas) and humans. Fishermen began inadvertently provisioning these foraging turtles with fish offal discarded from their boats. Although initially an indirect supplementation, this activity became a popular attraction for visitors. Subsequently, demand for this activity increased, and direct supplementation or provisioning with food began. Food items offered included raw whole fish (typically a mixture of false herring [Harengula clupeola] and pilchard [Harengula humeralis]), filleted fish, and lesser amounts of processed food such as hot dogs, chicken, bread, or various other leftovers. Alterations in behavior and growth rates as a result of the provisioning have been documented in this population. The purpose of this study was to determine how tourism-based human interactions are affecting the overall health of this foraging population and to determine what potential health risks these interactions may create for sea turtles. Juvenile green sea turtles (n=29) were captured from four sites off the coast of Barbados, West Indies, and categorized into a group that received supplemental feeding as part of a tour (n=11) or an unsupplemented group (n=18) that consisted of individuals that were captured at sites that did not provide supplemental feeding. Following capture, a general health assessment of each animal was conducted. This included weight and morphometric measurements, a systematic physical examination, determination of body condition score and body condition index, epibiota assessment and quantification, and clinical pathology including hematologic and biochemical testing and nutritional assessments. The supplemented group was found to have changes to body condition, vitamin, mineral, hematologic, and biochemical values. Based on these results, recommendations were made to decrease negative behaviors and health impacts for turtles as a result of this provisioning.

Estimates of the non-market value of sea turtles in Tobago using stated preference techniques

Economic benefits are derived from sea turtle tourism all over the world. Sea turtles also add value to underwater recreation and convey non-use values. This study examines the non-market value of sea turtles in Tobago. We use a choice experiment to estimate the value of sea turtle encounters to recreational SCUBA divers and the contingent valuation method to estimate the value of sea turtles to international tourists. Results indicate that turtle encounters were the most important dive attribute among those examined. Divers are willing to pay over US

Outcompeted by an invader? Interference and exploitative competition between tropical house gecko (Hemidactylus mabouia) and Barbados leaf-toed gecko (Phyllodactylus pulcher) for diurnal refuges in anthropogenic coastal habitats.

62 per two tank dive for the first turtle encounter. The mean WTP for turtle conservation among international visitors to Tobago was US

Shorebird hunting in Barbados: Using stable isotopes to link the harvest at a migratory stopover site with sources of production

31.13 which reflects a significant non-use value associated with actions targeted at keeping sea turtles from going extinct. These results illustrate significant non-use and non-consumptive use value of sea turtles, and highlight the importance of sea turtle conservation efforts in Tobago and throughout the Caribbean region.