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Hawksbill Turtles of Hawaii

Hawaii Volcanoes NP
Larry Katahira
In the United States, recent hawksbill nesting has been documented only in southern Florida and in the Hawaiian Islands. In the Hawaiian Islands, regular nesting has been documented on Molokai, Maui and Hawaii with nearly 90% of nesting turtles occurring on Hawaii Island.

Since 1989, volunteers have been instrumental in studying and protecting the endangered hawksbill turtle (Eretmochelys imbricata), which is indigenous to Hawaii. Honu’ea is the rarest turtle in the Pacific Ocean, with not more than 10-20 individuals nesting per season in the main Hawaiian Islands.

Between 1989 and 2002, ten nesting beaches were located and principal nesting sites were monitored. The nesting season, from hatchling emergence, begins in approximately late May and extends through January, with the peak egg laying period from late July to mid September.

A total of 55 turtles were tagged and 480 nests were documented, mostly occurring at two principal sites, Kamehame and Apua. Individual turtles laid between one and six clutches per season. Mean nest success was 74.2%. The mean interval from nesting to renesting within a season was 20.7 days, the mean clutch size was 178.3 eggs, and the mean incubation period was 64.2 days. Approximately 50,000 hatchlings have made it safely to the ocean.

Following the nesting season, hawksbill turtles migrated to their resident foraging habitat, primarily along the eastern coast of Hawaii Island. After two to five years, these turtles returned to their same nesting beach, demonstrating a high degree of nest site fidelity. The primary limiting factors affecting nesting and hatchling success were predation by mongoose, alien plants, artificial lights, hatchling strandings, vehicular traffic and recreational use of nesting beaches. A total of 1,300 mongooses have been removed from the turtle nesting beaches.

Volunteers in Hawaii monitor nesting activities, handle and tag turtles, rescue stranded hatchlings, excavate nests, record field data, and trap and euthanize introduced predators (mongoose, rats, feral cats) to protect turtle eggs and hatchlings.

Data from the field seasons is regularly collected, analyzed, and made available to the park’s GIS system along with associated information such as photographs, field records and files.

The success of this turtle nesting program is directly attributable to great volunteers, the development of strong, supportive partnerships with a variety of agencies and organizations, and a continuing commitment to science based research to provide information to management for decision making and planning.

(808)985-6088, 985-6090 for more information

April 08, 2004