France Declares War on Bullfrogs

From IOL. (Local Sonoma County angle: Bullfrogs are one of the preditors of the California tiger salamander, an endangered species whose habitat is the Santa Rosa Plain. Perhaps someday we can form a local bullfrog militia.)

Le Haillan, France - Picture this: French hunters stealing out at night in pairs, one with a torch to light up the eyes of their prey, the other armed with a .22 calibre rifle equipped with a telescopic sight and a silencer.

Their quarry? Invaders from the United States - bullfrogs, to be precise, that bellow like cows and typically weigh in at a hefty 600 grams.

This is France, to be sure, but the end game of this hunt is not sauteed frog legs.

These marksmen are ecologists, out to exterminate the bullfrogs - a.k.a. Rana Catesbeina - which are threatening the local ecosystem.

"A man living in Vayres (30 kilometres east of Bordeaux) stocked his pond with them in 1968 as a joke, and a few years later every stretch of water in the region was full of them," said Luc Gueugneau, who works in the government agency overseeing wild animals and hunting.

The bullfrogs live for as long as nine years, hibernating from October to March, but the rest of the time gorging on local frogs, shellfish, insects, and even fledgling birds, said ecologist Mathieu Detaint.

They have virtually no predators, and each lay up to 25 000 eggs a year, against 10 000 laid by the local frogs.

"We tried draining the ponds, but it costs a lot and is not efficient enough because there are always some bullfrogs that remain," Detaint said.

One thing that did work, though, he said, was trapping the tadpoles and very young frogs in nets.

Said Gueugneau: "For the moment, hunting the adults with rifles has proved to be the most efficient way of attacking them, because it gets rid of those able to reproduce."

The hunting is done at night, as that is when the frogs are most active and easiest to spot.

"We carried out five hunts between September last year and this July, killing about 120 of them," Detaint said.

"At the start, the idea seemed ludicrous, but we became convinced little by little because they allowed us to eradicate all the adults at two sites where the system was tested."

The ecologists say they a full-scale eradication programme should be in place by 2007, and hope to fully eliminate the bullfrogs in five or 10 years.