Monday 24 June 2019

Green sea turtle nests could beat record highs on the Space Coast this season. Here’s why. – via Herp Digest

Orlando Sentinel, 6/21/19

The number of green turtle nests on the Atlantic coast have been on the upswing, surpassing the loggerhead turtle. Scientists are thrilled by this development.

During this time of year, sea turtles emerge from the ocean to lay eggs on the sand at night on Florida’s beaches.

The state accounts for 90 percent of the nation’s loggerhead nests, but another species also listed as threatened, the green turtle, has blown past the loggerhead on the Space Coast and is expected to post another record number of nests this year.

“So, this season is particularly exciting because this is the 'up’ year for green turtle nests,” said Ashley Lord, interpretative park ranger who leads turtle tours at Canaveral National Seashore.

Since Canaveral began protecting turtle nests from animal predators with metal screens in 1984, the female hatchlings that survived are now of reproductive age, returning to the beaches where they were hatched. There is also no light pollution and no housing development along 24 miles of beach.

During the last reproduction year for green turtles in 2017, the species surpassed loggerhead nests at Canaveral National Seashore. There were 7,736 green turtle nests to 4,556 loggerhead nests even though many of the green turtle nests later in the season were wiped out by Hurricane Irma.

Green turtles reproduce every other year. The nest screening program started in 1984, and the hatchlings that survived at higher rates would have returned to the same beaches 25-30 years later. Leatherback turtles also nest at Canaveral but result in fewer than 35 nests a year.

Female green turtles reproduce every other year and so far point-in-time counts for 2019 are higher compared to the same week in 2017 for Canaveral National Seashore as well as the nearby Archie Carr National Wildlife Refuge.

Turtle nests face obstacles in addition to hurricanes.

Last year, 1,000 nests were wiped out at Canaveral National Seashore due to predators including raccoons and feral hogs, said Kristen Kneifl, chief of resource management. So far this season, the raccoons got into about 250 nests. Canaveral has taken steps to eradicate the problem raccoons.

To protect turtles from prey, volunteers and a team of four biological technicians cover nests with 4-by-4-foot metal wire screens with holes large enough for hatchlings to crawl out of as they emerge into the world. The screens are anchored into the sand with pieces of bent rebar.

“Our numbers are getting more than our staff can handle on every given day,” Kneifl said. “They’ve got to place the screen. They’ve got to pound the rebar. And with over 100 nests a day, it’s too much.”
Volunteer Patty Lillie of Winter Park spent many years alongside staffers, locating nests at Canaveral National Seashore, riding in an all-terrain vehicle under the moonlight.

“It’s a workout — the most I’ve ever done is 28 [nests] in one night and I was toast," she said.

These days, she guides small groups at night so they can see loggerheads lay eggs.

“I love doing that part, too,” Lillie said of the tours, “because the more people experience something with an animal, the more they’re going to care about that animal.”

Visitors aren’t allowed to view green turtles laying eggs along Florida’s shorelines because it is not a permitted activity by the Florida Fish and Wildlife Conservation Commission. But scientists see them.

“To have a day when there are more green turtles nesting than loggerheads is very surprising because they were doing poorly for so long,” said Jane Provancha, an ecologist who has studied Florida’s sea turtles extensively.

But as the climate gets warmer, there is concern there won’t be enough male sea turtles to sustain long-term population growth. The warmer the sand temperature, the more likely the hatchling will be a female.

It’s a subject Provancha researched in the late 1980s with the late Nicholas Mrosovsky. They discovered that loggerhead hatchlings from 1986-1990 at Cape Canaveral Air Force Base were more than 90 percent female. Green turtles develop similarly to loggerheads, she said. Their differences can be found in migratory patterns and diet, among other factors.

“We believe there are more females to start off in the ocean when animals are released from their nest," she said, but experts still don’t know a lot about the gender ratio in the adult stage because the males tend to stay in the water while the females show up on the beach.

In Australia, she said, studies have estimated the gender ratio of turtles in the water is two or three females to one male.

“We could assume the same” for the Atlantic population, she said.

Warmer sand temperatures can also speed up when the eggs will hatch. They also can cause sea turtles to lay their eggs further north where it might be cooler, although green turtles will nest within five to 10 miles of where they were born. Loggerheads seem to nest within a 40-mile range.

Atlantic green turtles were listed as endangered only as recently as 2016, when they were downgraded to threatened under the Endangered Species Act. Loggerheads in this area also are listed as threatened.

The idea that there would be this many green turtles today couldn’t have been predicted 15, 20 or 30 years ago, Provancha said.

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