By ANDY NEWMAN/The New York Times

Runway 4 Left at Kennedy International Airport was closed for more than an hour on Wednesday morning. The cause: turtles on the runway.

Specialists from the Port Authority of New York and New Jersey removed about 100 diamondback terrapins from the runway around 10 a.m., said John P. L. Kelly, a Port Authority spokesman.

Some flights were delayed for up to 30 minutes, said a spokeswoman for the Federal Aviation Administration, Arlene Salac, but not too many: the runway is used relatively infrequently this time of year because of seasonal prevailing-wind patterns.

The runway becomes a turtle crossing every year around this time as the terrapins gear up to reproduce.

“They look for sandy spots to lay their eggs,” Mr. Kelly said, “and there is an ideal location on the other side of Runway 4L. They come out of the water and cross the runway to lay their eggs in the sand.”

Wildlife specialists for the Port Authority and the federal agriculture department relocated the turtles to an equally nestworthy area on airport property out of harm’s way, officials said.

“We just take them to a part of the airport where they can keep traveling west, but in a safe direction,” said,Allen Gosser, assistant state director for New York wildlife service for the federal agriculture department.

Kennedy Airport is largely surrounded by water, and diamondback terrapinsbreed in and around Jamaica Bay.

“This may be a major international airport, a gateway to New York City and the United States, but any facility that is built on water, sometimes your neighbors come in a hard-shell variety,” Mr. Kelly said.

In 2009, the same runway was closed due to occupation by 78 diamondback terrapins, engendering some interesting chatter from air traffic controllers.

The Federal Aviation Administration recorded 18 collisions between civil aircraft and diamondback terrapins from 1990 to 2007 (see page 39 of this pdf). None caused damaged to the aircraft.