• Dry Tortugas

    Dry Tortugas

    National Park Florida

Sea Turtles

Sea turtle hatchling swimming in front of Fort Jefferson

Sea turtle hatchling swimming in front of Fort Jefferson.

NPS photo by Brett Seymour

Sea turtles are often sighted around Dry Tortugas National Park. Originally named Las Tortugas (Spanish for The Turtles) by Ponce de Leon in 1513, this collection of small sand and coral islands is famous for the abundance of sea turtles that annually nest in the area. Five species of sea turtle are found in the waters of south Florida: loggerhead (Caretta caretta), green turtle (Chelonia mydas), leatherback (Dermochelys coriacea), Kemp's ridley (Lepidochelys kempi), and hawksbill (Eretmochelys imbricata).

 
Sea turtle

Sea turtle swimming.

NPS photo

All five of these species were once more abundant; however, all five species are now listed as either threatened or endangered under the Endangered Species Act of 1973. Loggerhead, green, and hawksbill turtles can sometimes be spotted lounging on the surface of the sea on the trip between Key West and Dry Tortugas National Park. The name Las Tortugas was changed to Dry Tortugas on nautical charts used for navigation to indicate to mariners that no fresh water was available on the islands. The name change had nothing to do with how wet, dry, or thirsty the local sea turtles were.

 

Please Remember that it is Illegal to Disturb
Sea Turtles and Sea Turtle Nests!

Section 9 of the Endangered Species Act makes it "illegal to take (includes harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect; or to attempt any of these), ... any endangered fish or wildlife species..." The Florida Fish and Wildlife Conservation Commission interprets the disorientation of sea turtles due to artificial lighting as a violation of the Act. In addition, many dive outfitters even consider harassment to include a diver causing a turtle to alter its course when swimming. Please contact a park ranger to report a person disturbing a sea turtle nest or an injured, dead, or harassed sea turtle.

 

Monitoring Sea Turtle Nesting Activity

 
NPS biologist inventorying a sea turtle nest

NPS biologist inventorying a sea turtle nest.

Julie Marcero, NPS volunteer

Dry Tortugas National Park is the most active turtle nesting site in the Florida Keys. Park biologists have been monitoring sea turtle nesting activity within park boundaries since 1980. Five of the park's seven islands (East, Loggerhead, Bush, Garden, and occasionally Middle key) are surveyed throughout the nesting season to document the presence of turtles. The masked booby colony on Hospital Key precludes monitoring on that island. And, unlike the other islands, Long Key is made of coral rubble, not sand, and therefore is not monitored because historically it has had less than 1% of nesting activity in the park.

 
Tracks of a nesting female sea turtle.

Tracks of a nesting female sea turtle.

Photo courtesy of Kristen Hart, USGS

Tracks and other signs left on a beach by a sea turtle emerging from the sea are called a crawl. If the conditions are not right for nesting and a female sea turtle abandons her nesting attempt, the resulting tracks are called a false crawl. If the conditions are right, however, the female turtle will use her rear flippers to excavate a nest into which she will deposit her clutch of eggs. After depositing her eggs, the female will use her front flippers to cover the egg chamber with sand before lumbering back to the water, leaving her eggs to incubate and hatch on their own.

 
Sea turtle nest

Sea turtle nest.

NPS photo

Biologists find sea turtle nests by looking for a characteristically shaped mound of sand on the beach. Each nest is marked and recorded and then checked for signs of hatchlings beginning about 45 days later. Although incubation takes about 60 days, the temperature of the sand determines the speed of embryo development, so the hatching period can cover a broad period of time. The speed of embryo development increases with increasing nest temperature. Cooler nests generally produce more males, and warmer nests generally produce more females.

 
Sea turtle eggs

Sea turtle eggs in a nest.

Photo courtesy of Kristen Hart, USGS

Sea turtle eggs are about the size and shape of a ping pong ball. After the eggs have hatched, biologists excavate the nest and record the number of hatched and unhatched eggs, live and dead turtles, and any observations such as signs of predation on the nest or indications of arrested development.

 

 

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