Canadian scientists warn about bullfrog proliferation

VANCOUVER, British Columbia — Canadian scientists are sounding the alarm about the spread of the nonnative bullfrogs, which are native to the eastern United States, grow as big as dinner plates and eat anything they can fit into their mouths — including ducklings, garter snakes, songbirds and mice.

“In their place, they’re fine,” said Trudy Chatwin, an endangered species biologist with the British Columbia Ministry of Water, Land and Air Protection, “but here they’ve just gone explosive.”

Chatwin once led an effort to manage the bullfrog boom, but provincial spending cuts have eliminated further funding for control efforts, leaving the voracious critters free not just to wrest habitat from native frogs but to eat them.

“They’re very opportunistic,” Chatwin said. “They eat other frogs, including the red-legged frog, which is now a blue-listed (endangered) species because of it.”

Lisa Burgess-Parker and others in the Langley Environmental Partners Society have been trying to rein in the bullfrogs for years, but their funding has been cut as well.

Herons, eagles, ospreys and snakes occasionally feed on young bullfrogs but not enough to make a dent, largely because bullfrogs are not native and thus are not part of the predators’ staple diet.

Purnima Govindarajula, a biologist studying the frogs for her doctoral thesis at the University of Victoria, said bullfrogs have spread halfway up Vancouver Island and are found as far as 150 to the east in the Okanogan region.

Bullfrogs were brought to the Vancouver area in the 1930s by an entrepreneur who planned to raise them for food.

When frog legs failed to capture the fancy of local diners, the bullfrogs were abandoned in a pond and were practically invisible for 40 or 50 years. They began proliferating about 15 years ago for reasons that remain a mystery.

•In Utah, where bullfrogs are established in only a few areas, Division of Wildlife Resources agents have been scrambling to find about 200 customers who bought bullfrog tadpoles from Ogden-area nurseries whose owners didn’t know that selling or possessing live bullfrogs was illegal.