Group Title: United States Virgin Islands animal fact sheets
Title: Hawksbill sea turtle
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Permanent Link: http://ufdc.ufl.edu/UF00093446/00002
 Material Information
Title: Hawksbill sea turtle
Series Title: United States Virgin Islands animal fact sheets
Physical Description: Book
Language: English
Creator: Division of Fish and Wildlife, Department of Planning and Natural Resources, United States Virgin Islands
Publisher: Division of Fish and Wildlife, Department of Planning and Natural Resources, United States Virgin Islands
Place of Publication: St. Thomas, VI
 Record Information
Bibliographic ID: UF00093446
Volume ID: VID00002
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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Department of Planning and Natural Resources
Division of Fish and Wildlife
U.S.V.I. Animal Fact Sheet #02

Hawksbill Sea Turtle
Eretmochelys imbricata


Phylum-
Subphylum
Class
Order
Family
Genus
Species -


Chordata
Vertebrata
Reptilia
Chelonii
Cheloniadae
Eretmochelys
imbricata


Identification Characteristics
* Mouth projecting, beak-like
* Carapace thick overlapping scutes
* Rear of carapace serrated along margin
* Prefrontal Scales 2 pairs
* Foreflipper 2 claws
* Costal scutes 4 pairs (anteriormost
costal scute does not contact nuchal scute)
* Gait (on land) alternating


- Animalia


Description
The hawksbill sea turtle (Eretmochelys imbricata) is a
small to medium sized sea turtle. Nesting females average
2 feet 9 inches carapace length, measured along the curve,
and can weigh as much as 215 pounds. Hatchlings are
quite small, averaging 1-3/4 inches carapace length and
weighing about 1/2 ounce. The elongated carapace is
sharply serrated along lateral and posterior margins. The
thickened scutes overlap, with greater overlap toward the
rear of the carapace. Hatchlings have a heart-shaped
carapace that elongates with maturity. Hawksbill sea
turtles have a narrow elongated head and, of course, a
distinctive "hawk-like" beak.
The hawksbill carapace is a dark amber color with
radiating brown streaks. This beautiful "tortoise shell"
pattern led to the wide harvest of hawksbills during the
early part of this century.

Distribution & Habitat
Hawksbill sea turtles are widely distributed in tropical
and subtropical oceans of the world. In the Western
Atlantic, they are found in the Bahamas and from Florida
to Texas, as well as areas where the Gulf Stream passes
close to shore. Hawksbills occur throughout the
Caribbean Sea.


Several different habitat types are used by hawksbills
throughout their life cycle. During their first years of life,
hatchlings are pelagic that is, they live in the open ocean
far from shore. In the Caribbean, hawksbill hatchlings are
thought to stay within a central, rotating oceanic current
known as the Caribbean gyre. There, they take shelter in
weed lines formed by the convergence of currents.
Juveniles (8 to 10 inch carapace length) reenter
coastal waters where coral reefs provide foraging habitat.
Juveniles generally reside on shallow reefs (<60 feet
deep), but as they mature the adults move to deeper
habitats and may forage to depths greater than 300 feet.
Ledges and caves found in and around the coral reefs
provide refuge and nighttime sleeping shelters.

Diet & Growth
During their pelagic phase, the diet of most sea turtles
is poorly understood. Hawksbill hatchlings and young
juveniles probably feed opportunistically in the weed lines
where they live.
Once the juveniles enter coastal habitats, their dietary
preference changes to sponges. Sponges are a difficult
meal, filled with silicious spicules (literally spines made
of glass) and occasionally with toxins. Hawksbills are the
only sea turtles, and one of only a few vertebrates, who
feed on sponges. Although hawksbills periodically feed


Taxonomy
Kingdom







on other organisms, their dietary specialization on sponges
makes then especially vulnerable to degradation of coral
reef habitats.
Little is known about the growth rates of hawksbills.
We believe that juveniles and young adults (1 to 2 feet
carapace length) grow about 1-1/2 inches/yr. Older turtles
presumably grow at a slower rate, and the hatchlings grow
faster. Hawksbills are believed to live for a long time
(perhaps 80 years) but there is currently no accurate way
to determine sea turtle age.

Reproduction
In the Virgin Islands, hawksbill sea turtles may nest
throughout the year, however the peak nesting season is
from July to October. Nesting usually takes place at night,
but may occur during daytime as well. Owing to their
small size and relative agility, female hawksbills can
negotiate rocks and other obstacles to crawl high up onto
beaches. In contrast to other sea turtles, hawksbills will
dig nests under sea grapes or other vegetation beyond the
edge of the beach.
Nest preparation is an elaborate and time-consuming
effort. Females first sweep the loose dry sand away from
a nest site a process called "body pitting." The female
then uses her rear flippers to dig a hole by alternately
scooping sand with left and right flippers, flinging loose
sand forward over her head. She then proceeds to lay
approximately 130 eggs in the nest. The number of eggs
laid is directly related to body size, and a large female
may lay as many as 200 eggs in one nest. After laying,
females disguise their nests by spreading sand over the
area.
Female hawksbill sea turtles will lay between 1 and 7
clutches each year. Nesting activities are repeated
approximately every 14 days, with an average of 2.7
successful nests per year. Only about half of hawksbill
nesting attempts are successful (eggs are laid) and
unsuccessful nests are simply abandoned. This is why one
can see numerous body pits on the upper beaches.
The incubation period for hawksbill sea turtle eggs
averages 55-60 days, after which hatchlings emerge from
the nest and scramble towards the ocean.

Conservation
Decades of intensive harvesting of hawksbills for their
"tortoiseshell" have led to severe population declines.
The U.S. Fish and Wildlife Service has listed the
hawksbill as endangered throughout its range. CITES
(Convention on International Trade of Endangered
Species) has listed the hawksbill sea turtle under
Appendix I among the most endangered of the CITES-
listed animals and plants. All sea turtles are protected by
territorial law, which prohibits the harvesting of adults and
eggs. Unfortunately, existing regulations have not
eliminated poaching ofhawksbills. In the U.S.V.I.,
hawksbill eggs are frequently poached.


All sea turtles are susceptible to injury from boats and
propellers. They are air-breathing reptiles they must
come to the water's surface to breath. Boaters must watch
out for sea turtles and other basking animals (as well as
swimmers!) in near shore waters.
Sea turtles can ingest or become tangled in fishing
line, nets or other marine debris. This can lead to
amputation of tangled limbs, digestive problems, and
frequently to death. The turtle shown in the photo
(opposite page) had part of its left flipper amputated after
becoming entangled in fishing line.
Hawksbill sea turtles are also threatened by habitat
modification. Beach erosion and erosion control methods
have reduced or altered nesting habitats. Installation of
lighting in coastal areas interferes with the behavioral
responses ofhatchlings, reducing their survival. These
factors have also contributed to a decline in hawksbill sea
turtle populations.

What you can do to help
1. If you see any turtle nesting or hatching events, please write
down the date, time and location you saw the turtles then
call the Division of Fish and Wildlife at 340-772-1955 (on
St. Croix) or 340-775-6762 on St. Thomas/St. John to
report the event.
2. Hatchlings can crawl to the water themselves, if you see
hatchlings making their way into the water, please let them
complete the journey themselves.
3. Please make an extra effort to keep plastic out of the marine
environment.
4. Turtles, especially hatchlings, will head toward the
brightest light source on the beach. This used to be star and
moon light shining on the ocean, but today it may be street
or building lights. If possible turn off lights that shine on
and toward the beach, when hatchlings are emerging.
5. Do not take flash pictures or shine lights directly toward the
turtles it will disorient them. Like us, turtle eyes will
maintain the ghost image of the flash, only the hatchlings
see this as a bright area and will crawl toward it.
6. If hatchlings emerge during the day, you may protect them
from predators, and guide them to the waters edge.
7. If you see a nesting turtle do not crowd around it and do not
harass it. You may observe nesting from a distance. Be
sure to stay behind the front flippers of the turtle so that you
do not disturb her. No flash photography.
8. Occasionally turtles will nest during the day. If you see a
daytime nesting sea turtle, please call the Division of Fish
and Wildlife immediately.
9. For more information on this and other animals in the
Virgin Islands please visit our web site at:
www.vifishandwildlife.com
BY WILLIAM COLES AND WES TOLLER, 2003
THIS PUBLICATION WAS PRODUCED WITH FUNDS
FROM THE WILDLIFE CONSERVATION AND
RESTORATION PROGRAM (WCRP).
FOR MORE INFORMATION ON
ANIMALS OF THE U.S.V.I. CONTACT
THE DIVISION OF FISH AND WILDLIFE
6291 ESTATE NAZARETH, 101, ST. THOMAS, VI 00802
PHONE 340-775-6762 FAX 340-775-3972
OR
45 MARS HILL, ST. CROIX, VI 00840
PHONE 340-772-1955 FAX 340-772-3227




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