Dozens of turtles, presumably on a mating spree, shut down a runway at John F. Kennedy International Airport Wednesday morning for 35 minutes, causing flight delays of an hour and a half.

The 78 diamondback terrapins were picked up, put into a pickup truck and removed from the runway, said John Kelly, a spokesman for the Port Authority of New York and New Jersey. They were originally spotted around 8:30 a.m. by a pilot, who radioed the tower.

“It’s not unprecedented, but it’s not at all common,” he said.

He said that the turtles were perhaps attracted to the sand along one side of the runway, which juts into the water. “They tend to look for sand while they are mating,” he said. “Presumably, all these turtles were feeling amorous.” It is unclear whether the turtles pair off, or if the numbers indicated it was a group activity, he said.

There has been a surprising amount of half-shell news in the last year around the city. A two-headed one was stolen in Brooklyn last August. And a 60-pound tortoise showed up in the Bronx in April.

These turtles were 8 to 10 inches long and weighed 2 to 3 pounds. Mr. Kelly volunteered a number of turtle puns, saying the morning phenomenon was perhaps an ultimate example of “slow, sweet love.”