THE STAR (Toronto, Ontario) January 06 We've lost that croaking sound - Frog numbers keep dropping - Frog populations in serious decline around the world Loss of habitat said to be the major cause (Jerry Langton)
"Frogs are the best bait for bass," says Max Radiff, a retired teacher who used to run a bait shop in Kinmount, a resort town in the Haliburtons.
"I used to catch my own frogs and eat frogs' legs too — the big bullfrogs were always around trying to eat the little frogs, so we'd eat them. Some of them had legs as big as small chicken drumsticks."
Radiff has to use artificial lures now, though. "I had some ponds I'd go to regularly and there were millions of them there — no matter how many you took there seemed to be the same number every year," he says. "Then, one year it was like a curtain fell down and there were none left."
That's the way it happened all over the world. One year the ponds were full of frogs, the next they were empty. Many places that very recently held thriving populations of croaking and singing amphibians have since fallen silent.
"I collected all kinds of frogs when I was a student in California," says Richard Wassersug, a biology professor at Dalhousie University in Halifax and a renowned authority on reptile and amphibian populations. "I was saddened to see some of them are now threatened or endangered species."
Canada, where almost all reptiles and amphibians are at the very northernmost edge of their distribution, has been hit particularly hard. Although there is no truly accurate way to determine frog densities, the evidence that does exist is startling.
Manitoba used to have a thriving frog export business, sending whole leopard frogs to U.S. biological supply houses for students to dissect. In 1972, 1.2 million frogs were sent down south; in 1973, the number fell to 270,000 and by 1976 there were none at all. There was no change in the laws, no decline in demand — the frogs simply vanished. And it hasn't just been leopard frogs.
"I did my thesis in 1976 when frogs were still plentiful and have been back to the same place pretty much every year since 1983," says Frederick Schueler, curator of the Bishop Mills Natural History Centre and an expert on reptiles and amphibians, particularly those of Eastern Ontario. "Since then, I've only seen two immature frogs — that was back in 1992."
On a recent trek around Lake Ontario, it wasn't until Schueler made it to Presqu'ile Provincial Park halfway to Toronto, that he ran into thriving populations of amphibians. "I heard the booming of bullfrogs," he says. "And it had been so long since I heard it, I actually thought it was cattle."
There's no single reason why frog populations have crashed but it has been a worldwide phenomenon that scientists started noticing in the 1950s, but it did not become publicly acknowledged until the '80s. Some species have become extinct, many more are endangered.
"I'm reluctant to tell you that it's habitat destruction because people say that so often it's kind of lost some of its impact," Wassersug says. "But everyone accepts it as a major cause, and with amphibians, it's more complex than the space taken up by a house or a road."
Because of their unique life cycle, amphibians like frogs are particularly vulnerable to habitat loss. With very few exceptions, amphibians must spend their larval (tadpole) stage in water. But, because they are poor swimmers, the tadpole generally only survive to adulthood in numbers when there are no fish present. What few clean bodies of water remain in this country have usually been stocked with aggressive and voracious sport fish.
"If you have fish, you won't have frogs," Wassersug says. "One woman asked me why she didn't have frogs in her pond anymore and didn't realize it was because she had stocked it with goldfish."
What frogs need to survive is water that's too shallow, swampy or impermanent to sustain fish populations. Years ago, frogs could rely on puddles and ponds created by annual flooding along rivers to lay their eggs safely, but human settlement has put a stop to that.
"People like to live near permanent bodies of water," Wassersug says. "And they have worked very hard to prevent flooding." A few species have adapted to take advantage of the drainage ditches beside highways, but they're usually so full of runoff, especially salt, that few can survive for very long.
Radiff is sure the reason is pollution.
"The ponds are still there, but the frogs are gone," he says. "It's got to be pollution. I've seen what acid rain and especially acid snow can do to aquatic plants — and frogs are especially sensitive to pollutants."
Pollution has also been cited as a culprit for population declines, but no one single chemical has been determined to be more noxious than the others, as DDT was found to be responsible for declining raptor populations in the 1960s. "How can you know which one is responsible? It's a witch's brew of chemicals out there," Schueler says. "Even organic fertilizers have been shown to burn holes through the skin of amphibians."
Sometimes, human intervention can make habitat too healthy for amphibians.
"When fertilizers enter a water supply, it can create an environment we call eutrophic — too rich in nutrients," Wassersug says. "A layer of green scum, algae, appears and kills almost everything else in the water." That's when things get even more esoteric for the unfortunate amphibians.
"Snails feed on the algae and rapidly multiply," he says. "And there's a parasite called a trematode that spends part of its lifecycle in snails and has been linked to frog deaths in the U.S."
As if dying in massive numbers were not enough, remaining frog populations have had to put up with deformities — particularly common on the banks of the St. Lawrence River — and the remarkable fact that many male frogs on the Prairies are transforming into females before they can breed.
While the situation may appear hopeless, the few frogs left in Canada can be protected and coaxed to breed when and where conditions are right.
"A friend of mine in Rochester, N.Y., has transformed her backyard into a frog breeding area," says Schueler. "All she did was put a little pond in there with some ground cover. She now has three species of frogs breeding there when there were none in the area before."
Of course, not everyone can build a pond in their backyard, but there are things people can do to ensure frogs don't become extinct in their neighbourhood.
"People should avoid using herbicides and insecticides on their lawns, not stock fish in every body of water they find and provide hiding places around shorelines for frogs to hide in," Wassersug says.
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