Hawksbill Sea Turtle

(Eretmochelys imbricata)

General Characteristics

The hawksbill gets it name from its bird-like, pointy beak and its relatively narrow head measuring approximately 12 cm (4.7 in.) across, with two pairs of prefrontal scales. Their carapace (shell) is oval shaped, with thick overlapping scutes, a strongly serrated posterior margin, and four pairs of costal scutes; overlapping scutes are unique to this species. They are often boldly marked with orange, yellow and brown variegations, making their carapace highly desirable for use in artisanal products. Their plastron is a light yellow to white color.

Size

The hawksbill is one of the smallest turtles, measuring up to 90 cm (3 ft.) in carapace length, and weighing up to 80 kg (176 lbs.). Their front flippers are medium in length compared to those of other species and each flipper has two claws.

Habitat
Hawksbills are the most “tropical” of all sea turtles since they are typically found in tropical and subtropical waters of the Atlantic, Pacific and Indian Oceans. They are found frequenting coastal reefs, rocky areas, estuaries and coastal lagoons. This species is also widely distributed in the Caribbean Sea, the northern Gulf of Mexico, the Greater and Lesser Antilles and along the Central American coastline south to Brazil. In the eastern Pacific Ocean, hawksbills have been observed in the Gulf of California, throughout the northwestern states of Mexico, and south along the Central and South American coasts down to Colombia and Ecuador.

Diet

The hawksbill has a narrow head and beak-like jaws allowing it to get food from crevices in coral reefs. They feed on sponges, anemones, squid and shrimp. Hawksbills play an important role in the health of the coral reef ecosystem by functioning as keystone species, this means they are highly selective or feed on only specific groups of sponges therefore helping rarer species become established and compete successfully for space and nutrients on the reef.   

Nesting

It is extremely difficult to determine the age at which sea turtles reach sexual maturity; however, various models have predicted this age to be between 20 and 40 years. These estimates are based on growth rates, time from hatchling to juvenile stage, and gonad conditions. Females nest at intervals of two or more years; laying between two to five egg clutches per season, approximately 15 days apart. On average, hawksbills lay 160 small eggs in each nest; however, this species has also been recorded laying the largest nest of all species, with 250 eggs. Eggs incubate for about 60 days. Hawksbills are unique in the sense that, because of their small body size and great agility, they will nest on beaches with more difficult access.  For example, they can traverse fringing reefs that limit access by other species. The hawksbill is considered a solitary nester; however, there are major nesting spots throughout the Wider Caribbean.

Hatchlings

Hawksbill hatchlings are light to dark brown in coloration and are relatively small with a typical carapace length of about 40 mm (1.6 in.).

Migrations

Migration information is very scarce for this species due to the fact that over the years, relatively few hawksbills have been tagged (a technique used to study migration by placing metal or plastic tags on the flippers, each with a unique series for identification and information on where to return the tag if found) in comparison to other species. Also, due to their protected status, little information is gained from tags since those who intentionally or accidentally capture these turtles are afraid to return tag information. However, despite all this, recaptures have shown that this species carries out migrations of up to 2,000 km (1,243 mi). Their exact route will only be known through more intensive satellite tracking. For example, hawksbills tracked from Cuba have traversed the waters of the Atlantic coast of Central America and even down to the waters of Colombia, covering distances of up to 2,450 km. (1,522 mi), while others tend to stay within the island’s territorial waters.

Current Status

The World Conservation Union (IUCN) classifies the species as Critically Endangered of Extinction (facing an extremely high risk of extinction in the wild in the immediate future).

Threats

Despite the fact that international hawksbill trade is prohibited through the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the main threat to the hawksbill turtle continues to be the illegal capture of juvenile and adult turtles for their beautiful carapace, which is made into jewelry and other products commonly known as “tortoise shell”. There are other threats, such as the direct threat of egg harvesting, as well as indirect threats like the destruction of critical habitats for their survival, especially coral reefs which are negatively impacted by climate change, increased sedimentation and nutrient run-off.

Population Trends

Contrary to previous beliefs, recent studies show there has been a drastic decline in this species worldwide as well as in the Caribbean. For example, since 2000 until now, numbers of nests have consistently fallen in the most important nesting beaches of the Mexican states of Veracruz, Campeche and Yucatán. 

Inter-American Sea Turtle Convention

Cooperative efforts from a variety of governmental as well as non-governmental organizations to conserve distinct sea turtle populations inhabiting the American Continent have existed for many years.  The Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC), which entered into force in May of 2001, provides an opportunity for dialogue and action favoring sea turtle management.  The IAC is the only international body establishing legal instruments and guidelines that commit the Parties to, among others, protect and conserve populations of sea turtles and their habitat, reduce incidental capture and foster international cooperation for research and management of sea turtles. Currently, eleven countries- Belize, Brazil, Costa Rica, Ecuador, United States, Guatemala, Netherlands Antilles, Honduras, México, Peru and Venezuela – are Signatory countries, meanwhile two more, Nicaragua and Uruguay, have sent in the necessary instruments for accession to the Government of Venezuela, the official depository nation.

Due to the critical state of the hawksbill, during the past IAC Conference of the Parties, COP2IAC (November, 2004) the Mexican delegation called for joint research efforts to search for the cause of the recent drastic decline in hawksbill populations in an attempt to stop this negative trend.

Sources:

Caribbean Conservation Corporation & Sea Turtle Survival League (www.cccturtle.org)

Chacón, Didiher. La Tortuga Carey del Caribe: Introducción a su biología y estado de conservación.© WWF 2005.  

(http://www.hawksbillwwf.org/php/Biologia/index.php)

NOAA Fisheries Office of Protected Resources (www.nmfs.noaa.gov/pr/species/turtles)

Pritchard, P.C.H. and J.A. Mortimer. 1999. Taxonomy, External Morphology, and Species Identification, p. 21-38. In: K.L. Eckert,

K.A. Bjorndal, F.A. Abreu G. and M.A. Donnelly (Editors), Research and Management Techniques for the Conservation of Sea

Turtles. IUCN/SSC Marine Turtle Specialist Group Publ. No. 4. Washington, D.C.

Wider Caribbean Sea Turtle Conservation Network (www.widecast.org)

Published by:

Pro Tempore Secretariat of the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC), San Jose, Costa Rica, April 2005

Edited by:

Belinda Dick

English Translation:

Belinda Dick

Photo Credits:

Hawksbill - M. Scharer, 2005

Hatchling - R.G. Santos

Hawksbill products – Caribbean Conservation Corporation

Illustrations:

Tom McFarland