You might expect the whirring blades of a helicopter to spark concern or annoyance from animals in the vicinity. But for the reptilian residents of a crocodile farm, a low-flying chopper seemed to signal mating season.

"All of the big males got up and roared and bellowed up at the sky, and then after the helicopters left they mated like mad," John Lever, owner of the Koorana Crocodile Farm in Queensland, Australia, told ABC.

It's not quite clear what about the Chinook helicopter excited the crocs, but experts suspect the animals may have mistaken it for a thunderstorm. That's right, thunderstorms really get crocs riled up.

October and November are spring months for Australia and are typical mating periods for the country's saltwater crocodiles. It's also the rainy season, when thunderstorms are common for parts of the continent.

"Usually, mating is a seasonal thing because [crocodiles] want to coincide with the best time to lay their eggs in a burrow or nest," herpetologist Mark O'Shea from the University of Wolverhampton told Live Science.

Mating during the stormy season means that when females lay their eggs weeks later, the weather is usually less severe so their eggs will have a lower risk of drowning in a flood.

So the timing seemed right, and the sound and vibrations from the chopper may have mimicked a thunderstorm signaling to the male crocs that it was go time. The motion of the Chinook's blades may have also caused changes in the barometric pressure similar to a storm.

Or, another theory, is that the crocodiles may have mistaken the helicopter's roar for the bellows and splashing tails of other males, O'Shea said.

Whatever the cause, the next step will be for the female crocodiles to make nests for their eggs. Using soil and rotting vegetation, they create mounds where dozens of eggs incubate.

Over the course of about three months, the mothers then aggressively protect their eggs.

Lever's farm has about 3,000 of the reptiles, which he raises for their meat and leather and as a tourist attraction.

This article was originally published by Business Insider.

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