Low-flying helicopter puts Australian farm's crocodiles in the mood

Oct. 3 (UPI) -- The owner of a crocodile farm in Australia said mating season started early this year thanks to the males being put into the amorous mood by the presence of military helicopters.

John Lever, who established the Koorana Crocodile Farm in Rockhampton, Queensland, in 1981, said the bulls among his stable of about 3,000 crocodiles were sent into a mating frenzy when a Chinook helicopter came in low over the farm.

Lever said helicopters are frequently seen over the area as the Singapore Armed Forces hold bilateral military training operations in the Shoalwater Bay Training Area and pilots use the croc farm as a marker point.

He said one helicopter came in low to get a good look at the animals, and the result was a flurry of reptile romance.

"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," Lever told the Australian Broadcasting Corp. "There's something about the sonic waves that really gets them stirred up."

Cameron Baker, a Charles Darwin University researcher who specializes in crocodiles, said the animals might have mistaken the sound of the chopper for the call of a competing male.

"It might be producing a very low-frequency 'thump, thump' as it hits the water," Baker said. "That may just coincidentally be similar to some of the sounds big male crocodiles produce to say, 'Hey, this is my turf.' We're still not sure how they use the sound and what it communicates."

Craig Franklin, a professor of zoology at the University of Queensland, suggested the helicopter's low altitude may have caused the crocs to detect a change in the barometric pressure similar to a thunderstorm, which often signal the start of their mating season.

"But alternatively, it could be the low-frequency noise created by helicopters," Franklin said. "We don't know what happens in farms, but our research shows that in the field they respond to rainfall events ... and of course, they're often associated with a change in barometric pressure."