Saturday 24 September 2011

As Diamondback Terrapin nesting declines, center eyes habitat assistance (Via Herp Digest)

BRUNSWICK NEWS (Georgia) 30 August 11 (Anna Ferguson Hall)

Hidden under layers of grass and vegetation, the dozen turtle nesting boxes lining the Downing Musgrove Causeway to Jekyll Island go unnoticed by most causal observers. But for the endangered terrapin turtles that slip into the wire-lined boxes to hatch eggs, the habitat-enhancing tools are vital for survival.

From May to July, terrapin turtles use the boxes to lay and hatch eggs.

The most recent season for the turtles is a cause of some concern to staff members of the Georgia Sea Turtle Center. The number of nesting turtles dropped by half, said Terry Norton, executive director of the rehabilitation and conservation center on Jekyll Island.

The lower number is a mystery.

"We don't know if it was a barren year or if the terrapin population has had that significant of a decline," Norton said. "We don't have any exact numbers, but we do know, from observation and counts, that the number of nesting turtles is severely decreased."

Of the 12 nesting boxes on the sides of the causeway, three have been found to be more popular with turtles and are being labeled as hot spots, where the majority of the season's nesting turtles migrated to lay eggs, Norton said.

Raccoons - or at least one raccoon - have been a nuisance to nesting turtles this past season. A box in one of the three hot spots was broken into by a raccoon or raccoons on several occasions, Norton said. Watching the intruder on an camera placed inside the box, Norton was able to see the small night mammal squeeze between the fencing protecting the box and steal eggs.

"This is the first time we've ever had a raccoon get inside a box," he said. "We'll now have to figure out the best way to keep them away." At the sea turtle center, the hatchling numbers were also down by a large percentage. Norton and staff regularly hatch eggs from terrapins struck by cars on the causeway or hurt in the area, but this season, they were far less active than usual.

Only 40 eggs were hatched at the center this year, compared to 110 last year. Norton isn't sure of the cause of the lower number. Norton has noticed another strange trend: More males were hatched than females. He said it's likely because temperatures in the nesting boxes were lower along the causeway than in normal hatching territories. The lower temperatures made for more males, he said.

Norton and staff are conducting a study to figure out which nesting box sites would benefit most from being made warmer in order to decrease the male bias condition developed this year, he said. "Lower temperatures make more males, and we need to find the boxes that would benefit most from being about 86 degrees," Norton said. "We are trying to balance out the male-female ratio to help keep the population healthy."

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