School's in session in Loggerheads 101From the October 6, 2010 Issue
HOLMES BEACH – There’s a lot to learn about loggerheads, according to former teachers and Anna Maria Island Turtle Watch and Shore Bird Monitoring volunteers Glenn and Claudia Wiseman.
Loggerhead sea turtles have laid 137 nests on Anna Maria Island since turtle season began on May 1, with the last 20 nests expected to hatch by the end of the season on Oct. 31, they told a group at the Episcopal Church of the Annunciation on Monday night.
While 137 nests may seem like a lot, turtles lay that many nests and more on east coast beaches each night, Claudia Wiseman said.
Still, Glenn Wiseman said, it’s important to protect the nests on Anna Maria Island because female turtles return to their hatching beaches to nest decades later, and if no turtles hatch from the Island, nesting here will end.
The turtles’ homing instinct is a mystery, but is thought to be related to the scent of the sand, the sound of the waves on a particular beach, or perhaps magnetic imprinting, she said.
It’s common for there to be as many “false crawls” each season as there are nests, she said – a false crawl happens when a turtle comes ashore to lay her eggs then returns to sea before doing so, perhaps because of lights, beach furniture, predators, people on the beach or other reasons. After several false crawls, a turtle will usually lose her eggs in the Gulf, where they drown.
Natural deaths don’t bother turtle volunteers as much as deaths caused by humans, because natural deaths make hatchlings part of an important food chain, she said.
Deaths caused by people are mostly due to lights. Because turtles see different wavelengths of light than humans, they are drawn to light on the horizon that people don’t see, nature’s way of getting them into the relative safety of the water as soon as possible after hatching. Street lights, flashlights and lights from inside condos and hotel rooms can lead them away from the Gulf.
While some think it’s clever to use a flashlight to draw turtles into the water, they don’t realize they’re attracting fish – or predators – at the same time, she said. If hatchlings waste energy from their egg sacs trying to find their way back to sea after being disoriented by lights, or if their egg sacs are disturbed after being handled by people, they may not reach the safety of the sargassum beds where they feed, some 25 miles out to sea.
For these and other reasons, it’s against the law to disorient turtles with lights or to touch them.
Turtle Watch volunteers are an exception – they sometimes must dig up and relocate nests that are laid too close to the water, which puts the eggs in danger of drowning. Occasionally, a nest laid near bright lights is allowed to hatch with a cage over it, and the hatchlings are placed in a bucket and released in a darker location.
While the overall sea turtle population is decreasing, partly because of the Deepwater Horizon oil spill in the northern Gulf, Anna Maria Island beaches have so far remained safe from the oil for turtle nesting, he said.
Some turtle facts the Wisemans shared:
• Turtles usually lay nests and hatch at night.
• Nests are 1 to 1.5 feet deep and contain 80 to 100 eggs.
• A mother turtle takes about two hours to dig a nest and lay her eggs.
• A mother turtle can lay 1,000 eggs per season.
• About one in 1,000 eggs makes it to maturity.
• Turtles inside eggs breathe air, and can drown if a nest is underwater for several hours.
• Predators include cats, raccoons, fire ants, poachers and - after hatching -birds.
• Eggs develop into males at the bottom of the nest where it’s cooler, and into females near the top of the nest, which is warmed by the sun.
• Nests hatch between 55 and 70 days after they are laid.
• Turtles in a nest hatch over two to three days, but wait for the last one to hatch before bursting out of the nest.
• Hatchlings may swim for 25 miles to reach the safety of the sargassum beds where they feed.
• Male turtles seldom, if ever, return to shore after they hatch.
• At sea, turtles face the most danger from sharks, plastic bags – which look like their favorite food, jellyfish – and boats.