To get to the other side to lay eggs on the sandy shores of theJamaica Bay Wildlife Refuge, which borders the airport in New York City's borough of Queens, authorities said.
Ron Marsico, a spokesman for the Port Authority of New York and New Jersey, which oversees operation of the region's airports, said about 150 diamondback terrapin turtles were spotted on Wednesday morning crossing Runway 4L.
Pilots from Jet Blue and other airlines halted their big birds and let the expectant reptiles pass, said Marsico.
"Flight delays attributed to turtles were minor, about 15 minutes or so," said Marsico.
Port Authority staff rushed out to the tarmac where, between takeoffs and landings, they scooped up the turtles and helped them on their way, he said.
Naturalists said the 185-acre Jamaica Bay may be the diamondback's most popular breeding ground in North America.
"It happens every year at about this time. It's the great migration, and this is the peak of the season," he said.
Flights were rerouted to another runway, as waves of turtles pressed on with their march to the bay.
"At one point, we decided to heed Mother Nature and use other runways. This is not impacting flights," Marsico said.