Hawksbill sea turtle

 

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Classification:

Global Population

Description and Natural History

Physical Description
The hawksbill sea turtle is named for its hooked, beak-like upper jaw which helps differentiate it from other sea turtles. Hawksbills are medium-sized sea turtles. Adults grow to approximately one meter (3.3 feet) in length and weigh about 80 kilograms (176 pounds). Males have a longer, thicker tail than females. Hatchlings weigh between 13.5 and 19.5 grams (0.03 - 0.04 pounds) and have a carapace length of about 42 millimeters (1.7 inches).

Hawksbills are well known for their beautiful carapace (shell) which is often referred to as “tortoise” shell. The color of the overlapping scales varies with location but is mostly brown with dark and light spots and streaks, and a lighter yellow or white belly.

Natural History
Hawksbill sea turtles inhabit tropical and subtropical waters in the Atlantic, Pacific and Indian Oceans.  They are widely distributed in the Caribbean Sea and western Atlantic Ocean, the Greater and Lesser Antilles, and along the Central American mainland south to Brazil. They are most commonly found in the United States in Puerto Rico and its associated islands, and in the Virgin Islands.

Sightings north of Florida are rare but they have been recorded in all eastern seaboard states as far north as Massachusetts, except Connecticut. There have been no sightings of hawksbill turtles off the west coast of the mainland US, but they do occur off Mexico, along the Central and South American coasts to Colombia and Ecuador, and in the Hawaiian Islands.

Hawksbill sea turtles are associated with coral reefs but can also be found on rocky outcrops, where sponges (their main food item) are found, or in mangrove-fringed bays and estuaries where reefs are absent.

Females come ashore to nest on isolated beaches beyond the high tide line, often under vegetation. Females nest every two to three years and can lay up to six clutches of eggs during one breeding season. They dig pits with their fore and hind-flippers and lay eggs in egg chambers in the moist sand. Each nest contains up to 230 eggs.

Hatchlings emerge from the sand at night when it is cool after an incubation period of 50 to 70 days. They immediately head to the sea where they remain in offshore beds of seaweed for a year or more, feeding and hiding from predators. They return to near-shore waters as juveniles. Adult females return year after year to the same beach where they were hatched to lay their eggs.

The hawksbill feeds predominantly on reef sponges, but also on sea anemones and invertebrates. It uses its beak to forage in the cracks of the reef. Little is known about migration in this species, but hawksbills are found year round near nesting sites. There are no reliable estimates of longevity.

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Status of the Species

Status
Hawksbill sea turtles are listed as Critically Endangered by the International Union for the Conservation of Nature and Natural Resources (IUCN) and, since 1970, by the US Endangered Species Act (ESA). They are also listed on Appendix 1 of the Convention on International Trade of Endangered Species of Wild Fauna and Flora (CITES), which makes it illegal to import or export hawksbill turtle products.

Threats to the Species
Humans have been the major threat, killing hawksbill sea turtles for the commercial value of the tortoise shell and also for leather and oil. This trade continues today. Nesting habitat is exploited and destroyed by beach development, erosion, vehicle traffic (compacting the sand over nest sites, hitting adults and making deep tracks in the sand which make it difficult for hatchlings to get to the water), and more.

Bright lights on developed beaches can disorient hatchlings or deter females from laying their eggs. Incidental takes in hook-and-line fisheries and net fisheries are a concern, as is entanglement in, and the ingestion of, marine debris.

Some sea turtles are injured or killed by boat propellers or in boat collisions. Poaching of eggs is a serious problem in Puerto Rico and, to a lesser extent, in St Thomas and St Croix. Degradation of reef ecosystems on which they depend is also threatening this species.

International Trade
Commercial trade in hawksbill turtles remains the biggest threat. The main countries involved in the trade are in the Caribbean and Latin America. Between 1970 and 1989, 1.2 million hawksbill turtles were killed to make jewelry, combs, and other decorative items.

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Authors and Sources

Sources
CITES. 2001. http://www.cites.org.

Euroturtle. 1996. http://www.ex.ac.uk.

Georgia Wildlife Federation. 1999. Hawksbill Sea Turtle. http://www.gwf.org.

IUCN. 2001. The 2000 IUCN Red List of Threatened Species. http://www.redlist.org.

NYS Department of Environmental Conservation. 1999. Atlantic Hawksbill Sea Turtle Fact Sheet.

US Fish and Wildlife http://ecos.fws.gov

MMFS. Office of Protected Resources.

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