I know you are looking at the above photo and saying to yourself, “That is no bird!” And you are absolutely right, it is a Leatherback Turtle, but it has a birding connection, so I am straying from the norm … again.
This turtle was spotted on a Westport Seabirds pelagic trip on Sept. 7. A pelagic trip is one in which a boatload of birders go looking for birds that live most of their lives on the sea; pelagic birds only come ashore to lay eggs and raise their young. This turtle is only the third leatherback to be seen by Westport Seabirds in the 20 years they have been in business. Those on board for this particular trip were part of a Seattle Audubon Master Birder class, and what a great day they had.
Size: Adults can weigh up to 2,000 pounds and hatchlings 1.5 to 2 ounces. Length of adults is approximately 6.5 feet, 2-3 inches for hatchlings. The Pacific population is smaller than the Atlantic population.
General Description: The Leatherback is the largest turtle in the world, and the only sea turtle that doesn’t have a hard shell. The carapace (top shell) is almost black, about 1.5 inches thick, and consists of a leathery, oil-saturated connective tissue overlaying loosely interlocking dermal (membrane) bones. There are 7 knobby ridges running the length of the carapace that taper to a blunt point above the tail. Their belly is a pinkish-white color. Their front flippers are proportionally longer than other sea turtles, and their back flippers are paddle-shaped, allowing this turtle to make long-distance foraging migrations. Their jaws are not the crushing chewing type as other sea turtles have, but have pointed, tooth-like cusps and sharp-edged jaws that are perfectly adapted for eating soft-bodied prey such as jelly fish. Their mouth and throat also have backward-pointing spines to help keep their prey in their mouth.
Habitat: Leatherbacks are pelagic (open ocean), but they also forage in coastal waters, and they are the most migratory and wide-ranging of sea turtle species. They have the ability to regulate their body temperature to suit their environment; with a counter-current heat exchange system, high oil content, and large body size, they can maintain a core body temperature higher than the surrounding water. Egg-laying females tagged in equatorial waters have been found off the coast of Newfoundland. They range from as far north as Alaska to as far south as the southern tip of Africa.
Nesting: Leatherbacks mate off the coast of nesting beaches and in migratory corridors. Females lay clutches of 80 to 100 eggs on sandy, tropical beaches, nesting several times a season at 8 to 12 day intervals. In about 2 months, the baby turtles hatch and head for the sea. The sex of the hatchlings is determined by the nest temperature. A mix of males and females occurs when the nest temperature is approximately 85 degrees; higher temps produce females, cooler temps produce males. After nesting, adult females head for more temperate waters which support high densities of jellyfish in the summer. Female hatchlings stay at sea until they reach sexual maturity, and usually return to the same beach from which they hatched. Male hatchlings spend their whole life at sea.
Migration: Leatherbacks undertake the longest migrations between breeding and feeding areas of any sea turtle, averaging 3,700 miles each way.
Conservation Status: The Leatherback lifespan is unknown for sure, but is thought to be about 45 years. It is estimated that only about one in a thousand hatchlings survive to adulthood. Their eggs are harvested despite laws to protect them, they are often entangled in fishing lines or nets, struck by boats, or die of ingesting floating plastic bags that look so much like jelly fish. The population of the Atlantic leatherbacks seems to be stable and may even be increasing, but the Pacific population has dramatically decreased due to egg harvest, fishery by-catch, coastal development, and highly variable food availability. They are being closely studied to learn more about them and how they can be saved.