Toronto Star
January 28, 2006


Rachel's summary: "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."

Frog numbers keep dropping

Frog populations in serious decline around the world
Loss of habitat said to be the major cause

By 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

"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

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

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

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.

'One year it was like a curtain fell down and there were none left'

Max Radiff

"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

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

Sometimes, human intervention can make habitat too healthy for

"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

"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

"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

"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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