You’re walking in a wet forest and a small brown lump starts to move on the ground in front of you. There’s a pretty good chance you’ve just seen a Western Boreal Toad. Look carefully in the photo to the right; that’s probably they way you’ll see them.
Their home
Boreal Toads are found in montane and sub-alpine woods and meadows, normally near water sources. Wandering around Kananaskis, you’re far more likely to see this toad than the only other toad in the area (the Canadian Toad, which isn’t found much outside the Bow Valley).
Look but don’t touch
The Boreal Toad is fairly common in Kananaskis country, and it looks exactly like you would think a toad would be expected to look. It’s covered in wart-like blobs, and is either olive or brown or dark green. You can’t get warts on you from the warts on them, but they do have glands on their head that produce a toxin that will give you a skin rash (and make their potential predators fairly sick). They’re easy to catch (they’re not fast; wash hands after touching) but will die in captivity.
The range of the Western Boreal Toads extends from the top of the Baja to the Yukon & Alaskan borders, and east as far as Wyoming, Montana and Colorado. Not all Boreal Toads can do mating calls; most of the population is referred to as “non-calling”. But our Alberta toads have vocal sacs, and so are referred to as the “calling” population.
Eating and reproduction
They are bug eaters, mostly beetles and ants, plus worms and slugs. Those bad toxic glands limit who preys on them; mostly it’s ravens and other birds. They mate in the spring in water, and eggs – up to 17,000 – are laid on aquatic plants. Yes, they do the classic tadpole thing like all frogs, then become mostly terrestrial as adults. They overwinter in hibernation in burrows, squirrel middens and beaver lodges – often communally – and are capable of digging their own holes.
A species of concern
As a species, they’re not doing that well. They are on the COSEWIC list as “Special Concern.” 50% of the global population has been lost in the last 200 years. You can read here the management plan in Canada for its recovery. Reasons behind these population trends are complex. While there is evidence that the population is expanding eastwards, it is shrinking in the south parts of it range. First, it needs fish-free water to survive; efforts to re-introduce fish in places has harmed the population. Second, and far more importantly, it’s susceptible to a fungus (chytridiomycosis) that attacks amphibians, and frogs in particular. In K-Country, the volunteer group RANA (Researching Amphibian Numbers in Alberta) keeps an eye on the degree of chytridiomycosis infections in our sample populations.
Thank early pregnancy tests
The chytridiomycosis fungus itself is relatively “new”. The first documented case of the disease resulting from it was in a frog in 1978 in the USA, and another frog almost simultaneously in Australia. It’s possible these cases could have been related to an African frog, which started being widely exported in the 1940’s. It appears to be a fungus carrier but immune to its effects. That frog (the African Clawed Frog) had a unique trait. When injected with a human woman’s urine, if the frog ovulated, it was proof of pregnancy. This was the world’s first pregnancy test. It was widely used from the 1930’s to the 1960’s, spreading African Clawed Frogs (and possibly the fungus) to medical labs around the globe.
Meet more of the cool critters of K-Country here!