terrapinA runway at New York’s JFK airport was closed Thursday after “massive numbers” of turtles invaded the landing strip, causing flights to be delayed by up to 90 minutes as ground crews rounded up the wayward terrapins.

Airport authorities were alerted to the situation around 8.30 am local time when a pilot taxiing for takeoff reported spotting several of the creatures on the tarmac, according to the Guardian.

As more turtles emerged onto the runway from Jamaica Bay, which abuts the airport, airport officials halted flights for 12 minutes while the animals were cleared away.

But the Federal Aviation Administration was then forced to cancel takeoffs and landings completely amid new reports of “massive numbers” of turtles on the runway. Ground crews removed at least 78 from the scene.

“Apparently this is something the tower has experienced before,” said FAA spokesman Jim Peters. “I guess it’s the season for spawning.”

Jets hit turtles at JFK several times a year, usually in late June or early July, according to the FAA’s wildlife strike database. The diamondback terrapins, which grow to about eight inches long, are common to Jamaica Bay.