Chorus frogs and other amphibians fill Alberta's wetlands with sound

Homestretch naturalist Brian Keatingoften makes his weekly appearance on the program via satellite phone, from the farthest corners of the planet.

However, on Monday's show Keatingrode his bicycle into the studio, stopping en route in Calgary's Edworthy Park to check out the frogs.

Q: What did you discover, Brian?

A:I came across a city wetland last week and it was alive with sound.It [was the sound of]a boreal chorus frog. It's actually a tree frog that lives here in Alberta. It's not really a high climber. It's not really designed like some of the other tree frogs you'll find here in the tropics, but it's still classified as a tree frog. And it's got the widest distribution of any amphibian in the province.

Q: Are these frogs found throughoutthe province?
A:Historically, it's found everywhere in Albertaexcept of course in the alpine environments. Now, it's excluded only from areas where there's higher pesticide use.

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Q: Are thereother, similar frogsin Alberta?

A:There's only oneother frog that's similar to the boreal chorus frog and that's the wood frog, which also lives in Alberta. And italso has a stripe throughthe eye, which the boreal chorus frogalso has.

But it's larger andhas tworidges down the back.

There's not a lot offrog species in Alberta, but that boreal chorus frogis the onethat is the most common.

Q: Are they easy to find?

A:No they're not. They're easy to hear.

Actually when I biked to the studio today, I went via Edworthy Park becausethat's where I came across the pond, and I stopped there just a few minutes ago, and it was quiet. So they may have finished their breeding cycle.

Or maybe because it was just too darn hot for them.

The best time to hear them is early in the morning,or late in the evening but they'll even call all night.

But they're very difficult to find as soon as you start to approach to where the call is coming from, they stop.

Q: What do they look like?

A:They're the smallest amphibian in Alberta. They're less than an inch-and-a-half long at their longestthey're usually about an inch or so. And they're also known as the striped chorus frog, becauseof the threedark stripes that are on their body and a stripe throughthe eye and along the side.

They produce that sound, like all frogs, by expelling air out of their lungs, over their vocal chords but they fill up an air sac on their throat.

It's absolutely amazing.

That balloon acts as a resonator andthey just recycle the air back and forth over top of their vocal chords. That's how they make the sound.

I remember one time down in South America, I was camping in the woods, and a frog jumped in our canoe,in the night. There was a 50 gallon drum it was a riverboat and the 50 gallon drum was empty. The frog sat under the drum and it amplified his call about 50-fold. I'm sure he was the proudest frog in the forest.

That's why they have those air sacs to amplify the sound.

Q: And the lady frogs love it?
A: Absolutely, 100 per cent. It's a nuptial call and that's why they were calling last week, and are probably still calling now, in some areas. It attracts females. Discourages males from coming into the area.

So if you've got a good, robust call, like that one in that canoe in South America, I'm sure no male came close if the call is robust andstrong that'll discourage other males from coming into his territory.

The problem with doing all that calling is it potentially attracts predators, so it's a delicate balance: should I mate, or should I get killed?

Q: How are they doing here?

A:When I was a kid, I remember seeing leopard frogs everywhere! And now, you're hard pressed to find in fact, a number of years ago, the CalgaryZoo started a program when I was working at the zoo and they started to monitor leopard frogs.

They've got an ongoingleopard frog program, looking at 68 different wetlands around southern Albertathey're even testing the water to see if there's frog DNA in the water. That way, they can figure out if there's frogs in a certain body of water without having to catch the frogs.

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Interesting method but yeah, they're looking at it. They've been in decline since the 1970's. It's one of those things. Obviously we're having an effect on the environment and it's probably due to a number of different reasons but all the more reason to kiss a frog next time you see one.

With files from The Homestretch