Babies, Not Birds and Bees, Made Turtles Come Out of Shell
Jamaica Bay, which includes Kennedy International Airport, has seen its population of diamondback terrapin decline more than 25 percent since 1999 — the 78 turtles on the runway last week notwithstanding.The 78 turtles that delayed planes at Kennedy International Airport last week were very likely not in search for love, contrary to the Port Authority’s theory, but in search for safety for their yet-to-be born babies, said biologists (and our readers in their comments).
Russell Burke, a biologist who has been studying turtles in Jamaica Bay (which includes the airport) for a decade, said that the diamondback terrapins were very likely all females, as the only terrapins seen on land are nesting females. In New York, the terrapins lay between one and three nests of eggs per year, with about 13 eggs each time, though perhaps 90 percent of those eggs fall victim to raccoons.
They were probably not mating, as terrapins mate underwater, which means the act is rarely observed — even in captivity. Female terrapins will often mate with multiple males, which are significantly smaller, and carry the sperm for a long time, meaning that one batch of eggs could be fathered by multiple turtles.
The diamondback terrapin population has declined more than 25 percent since 1999, in large part because of the loss of marshes in the bay, Dr. Burke said. He added that there is a huge amount of nitrogen pollution still coming into the bay from sewage overflow, which affects the vegetation.
The research at the Jamaica Bay Wildlife Refuge, a few miles away, has found that groups of females will often emerge on land on the first sunny day after a stretch of rain. This fact piqued City Room’s interest as June almost set a record for the amount of rainfall. Sometimes, Dr. Burke noted, more than 100 terrapins will be seen on one day.
The runway juts out into the water. He noted the turtles “are persistent about going to particular places, and will climb barriers and try to nest in the most ridiculous places for reasons that I assume make sense to them.” Since Kennedy Airport is built on marsh and uplands, he observed, “I assume the airport covers former feeding grounds and nesting grounds, and they don’t forget.”
The only other explanation for the turtle stampede might have been if a barrier to keep the terrapins off the runways somehow came down.
The turtle march may be more common than has been noticed. “I suspect that if you looked at records for wildlife incidents, way down below all the bird strikes would be some turtle strikes,” he observed.
By Jennifer 8. Lee, City Room
New York Times