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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