CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Pacific Hawksbill Sea Turtle -
Eretmochelys imbricata bissa

(Rüppell, 1835)
Click on a picture for a larger view




Pacific Hawksbill Sea Turtle Locations
Red: Pacific Hawksbill Sea Turtles are occasionally
seen off the southern California coast



observation link





Pacific Hawksbill Sea Turtle Pacific Hawksbill Sea Turtle Pacific Ocean
Stuffed and mounted Adult, Santa Barbara Museum of Natural History Skeleton,
National Museum of Natural History
Habitat in California, the Pacific Ocean
     
Atlantic Hawksbill Sea Turtle - Eretmochelys imbricata bissa
I have no pictures yet of live Pacific Hawksbill Sea Turtles, E. i. bissa, the Pacific subspecies of Hawksbill. Below are pictures of the Atlantic subspecies of Hawksbill Seaturtle, E. i. imbricata, which is similar in appearance to the Pacific Hawksbill which occurs in California.
Atlantic Hawksbill Sea Turtle Atlantic Hawksbill Sea Turtle Atlantic Hawksbill Sea Turtle
Captive rescued juvenile from the Gulf of Mexico. Sea Turtle Rescue Center, Sea Turtle Inc., South Padre Island, Texas.

Atlantic Hawksbill Sea Turtle Atlantic Hawksbill Sea Turtle Atlantic Hawksbill Sea Turtle
Close-up of shell of captive juvenile shown above. Adult, Puerto Rico,
© Michelle Tanya Scharer.
Hawk-shaped bill
   
Description
 
Size
Adults are 18 - 36 inches in shell length (46 - 91 cm) and 30 - 280 lbs. (Stebbins 2003)

Appearance
A small to medium-sized sea turtle with paddle-like limbs, a heart-shaped carapace with a central keel and a serrated rear edge.
The shields overlap like shingles, except in hatchlings and very old animals.
There are two pairs of prefrontal scales, and 4 costal shields on each side of the carapace.
The first costal shield does not touch the nuchal.
A long, narrow, sharp snout, like that of a hawk, gives this turtle its common name, Hawksbill.
Color and Pattern
Color is a dark greenish brown with a marbled or radiating pattern. The plastron is yellow and hinge-less. The head scales are black to chestnut brown in the center, with lighter margins. The chin and throat are yellow.
Male / Female Differences
Males have a long tail that extends well past the edge of the shell and a curved nail on the front of each flipper.

Life History and Behavior

Activity
Not much is known about Hawksbill behavior due to their solitary habits.
They are apparently diurnal, becoming nocturnal when nesting.
Hawksbills sleep at night on the bottom, surfacing occasionally for air.
They will readily bite to defend themseves.
Hawksbills are possibly the least migratory of sea turtles, but some tagged individuals have been recorded traveling long distances.
As with other sea turtles, the yearly activity during the breeding year of a Hawksbill includes a long period of foraging, migration to nesting beach, nesting, and migration back to the feeding grounds.
Diet and Feeding
Omnivorous. Feeds upon many invertebrates, preferring sponges (including toxic sponges) in some areas, mollusks, jellyfish, corals, sea anemones, sea urchins, crabs, rock lobster, fish, algae, sea grasses, and mangroves.
Breeding
Hawksbills mate in shallow water off the nesting beach and nest individually, not in large groups like other sea turtles. In the Pacific, nesting has been observed in Ecuador, Panama, Costa Rica, Nicaragua, Guatemala, El Salvador, Mexico, and Hawaii.

Females nest every 2 - 3 years between August and November at an average of 4 - 5 times per season. Sheltered, short, steep sandy beaches are preferred, and nests are often dug in the sandy soil among vegetation instead of open sand.

A female Hawksbill emerges from the ocean at night and crawls onto the nesting beach, using all four limbs to rapidly walk over the sand, instead of using just the two forelimbs to pull herself as other sea turtles do. She scrapes out a shallow body pit, then digs a nest and lays a clutch of 50 - 200+ eggs. Her total time on the beach is 1 - 2 hours. Nests are robbed by humans, and other mammals such as dogs, raccoons, and rats. The eggs hatch in 60 - 70 days and hatchlings emerge in the morning or in the evening and begin a frantic crawl towards the water. Hatchlings trying to get to the sea are eaten by birds, crabs, and other predators, and again by fish, octopus, sharks, and others once they reach the water.

Habitat
Inhabits shallow coastal waters in rocky places, coral reefs, mangrove-bordered bays, estuaries, and mud-bottomed lagoons. Sometimes found in deep water. Juveniles float on currents with patches of Sargassum weed.

Geographical Range
The Hawksbill species is found in the warmer parts of the Pacific, Indian, and Atlantic oceans. In the eastern Pacific, it is found from southern California to Peru. It is found infrequently in the Mediterranean Sea.

The subspecies found in our area E. i. bissa, the Pacific Hawksbill, is found in the tropical parts of the Indian and Pacific oceans, from Madagascar to the Red Sea, east to Australia, Japan and the Hawaiian Islands, and in the eastern Pacific from Peru to Baja California. Stragglers occasionally stray north to Southern California waters, probably during El Niño years when ocean temperatures rise.


Sea turtles can show up almost anywhere on the coast of California, but most sightings are not documented. 
I have not yet found any records of sightings of Pacific Hawksbill Sea Turtles in California waters. The only museum specimen from California I can find is from the Utah Museum of Natural History which is labelled as coming from the Hermosa Reptile and Wild Animal Farm, Hermosa Beach. There is no indictation whether the specimen was collected in California, but it probably was. Sources such as California's endangered animals list, Robert Stebbins' 2003 and 2012 field guides, and Ernst, Lovich, and Barbur (1994) state that this species has been seen in Southern California waters.

Full Species Range Map
Click Map to Enlarge

Notes on Taxonomy
Two subspecies are recognized - Eretmochelys imbricata bissa - Pacific Hawksbill, and Eretmochelys imbricata imbricata - Atlantic Hawksbill.


Alternate and Previous Names (Synonyms)

Eretmochelys imbricata - Hawksbill Sea Turtle (Stebbins & McGinnis 2012)
Eretmochelys imbricata - Hawksbill (Stebbins 2003)
Eretmochelys imbricata bissa - Pacific Hawksbill (Stebbins 1985)

Conservation Issues  (Conservation Status)
Endangered.

Getting accurate estimates of Hawksbill population numbers is difficult due to their behavior of nesting individually on scattered beaches. This behavior also makes assisting their reproductive success with nesting preserves ineffective.

Hawksbills have been in demand for their meat, their eggs and the translucent scutes of their shell, from which "tortoiseshell" products are made. They also suffer mortality through entanglement in fishing lines and nets, oil spills, and possibly from the development and degradation of nesting beaches, which is a worldwide problem with other species of sea turtles.

Other causes for the decline of sea turtles include the degradation of feeding habitats, ingestion of plastic garbage, especially plastic grocery bags (which look like jellyfish floating on the surface) and offshore boats moving so quickly that turtles are not able to move out of the way fast enought to avoid being killed or injured. Some authorities also question whether humans handling nesting females and doing research on nesting beaches is stressing the turtles and lowering reproduction and survivorship.
Taxonomy
Family Cheloniidae Sea Turtles Oppel, 1811
Genus Eretmochelys Hawksbill Sea Turtles Fitzinger 1843
Species imbricata Hawksbill Sea Turtle (Linnaeus, 1766)
Subspecies

bissa Pacific Hawksbill Sea Turtle (Rüppell, 1835)
Original Description
Eretmochelys imbricata - (Linnaeus, 1766) - Syst. Nat., 12th ed., Vol. 1, p. 350
Eretmochelys imbricata bissa -(Ruppell, 1835) - Neue Wirbelthiere zu de Fauna Von Abyssinien Gehorig, Vol. 3 , Amph., p. 4, pl. 2

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Eretmochelys - Greek - eretmo - oar, and chelys - turtle - refers to the shape of the forelimb
imbricata
- Latin - overlapping - probably refers to the scute pattern
bissa - Latin - bis - double, twice, and -sa suffix - refers to the concept of bissa as second species of Caretta

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Related or Similar California Turtles
C. caretta - Loggerhead Sea Turtle

C. mydas - Green Sea Turtle

L. olivacea - Olive Ridley Sea Turtle

D. coriacea - Leatherback Sea Turtle

More Information and References
National Oceanic and Atmospheric Administration - Hawksbill Sea Turtle

California Department of Fish and Wildlife

USFWS

Turtles.org


Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Turtles and Lizards of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Carr, Archie. Handbook of Turtles: The Turtles of the United States, Canada, and Baja California. Cornell University Press, 1969.

Ernst, Carl H., Roger W. Barbour, & Jeffrey E. Lovich. Turtles of the United States and Canada. Smithsonian Institution 1994. (2nd Edition published 2009)

Range and Nesting Information has been adapted from a number of sources, including:

Sea Turtle Conservancy

National Oceanic and Atmospheric Administration

Wickipedia

Witherington, Blair E. Sea Turtles: An Extroardinary Natural History of Some Uncommon Turtles. Voyageur Press, 2006.

Spotila, James R. Sea Turtles: A Complete Guide to Their Biology, Behavior, and Conservation. The Johns Hopkins University Press and Oakwood Arts, 2004.

Perrine, Doug. Sea Turtles of the World. Voyageur Press, Inc., 2003.

Arnold, E. Nicholas, and Denys W. Ovenden. Reptiles and Amphibians of Europe. Princeton University Press and Oxford, 2002.

Conservation Status

The following status listings are copied from the 2017 Special Animals List and the 2017 Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.

If no status is listed here, the animal is not included on either CDFW list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status, you can go to the NatureServe and IUCN websites to check their rankings.

Check here to see the most current complete lists.


This turtle is not included on the Special Animals List, maybe because it is not considered a species that occurs in California. It is considered to be critically endangered by the World Conservation Union.


Organization
Status Listing
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA)
California Endangered Species Act (CESA)
California Department of Fish and Wildlife
Bureau of Land Management
USDA Forest Service
IUCN
 

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