Frogs in the Columbia Valley

Columbia spotted frogs (Photo by Larry Halverson)

Some of the most cherished childhood memories for most of us are the ones that involve frogs. We chased them, we caught them, and we poked them with sticks to make them jump. Those fascinating little creatures provided us with hours and hours of fun on long summer days, and then for most of us were left behind, along with bikes, tree forts and the neighborhood swimming hole.

Little did we know then, that frogs are an integral part of the food web, that tadpoles keep our waterways clean by feeding on algae, that adult frogs eat large quantities of insects such as mosquitoes, and that frogs are an important source of food for many other creatures. They also produce an array of skin secretions which have significant potential to be used in medicines to treat many human conditions.

Like canaries in mines, frogs are valued as accurate indicators of environmental stress. So the disappearance of huge frog populations is clearly a warning to us that something is off-balance in our environment.

Frogs are amphibians. The word is derived from the Greek, meaning ‘two lives’, referring to the fact that most amphibians spend their early, larval lives as aquatic, herbivorous tadpoles and their adult lives on land as carnivores. Tadpoles have gills and the adults have lungs, however the skin of adult frogs is permeable, allowing them to absorb both water and oxygen through the skin.

Found all over the world, frogs can range in size from the tiniest at 10 mm (.04″) to an enormous 30 cm (12″) in length, weighing in at 3 kg (6.6 lbs). Life spans can range from just a few years to 6 or even 7 years.

There is a slight difference between frogs and toads, with toads generally having shorter legs and dry skin with wart-like bumps. It’s not always cut and dried however because some frog species tend to look similar to toads.

Here in the Columbia wetlands, we find the northwestern toad, the Columbia spotted frog and the wood frog, which is the only North American frog that is capable of surviving in Arctic temperatures because high glycogen levels in its cells act like anti-freeze. It is hoped that the leopard frog will be successfully re-introduced into the area in the near future.

Columbia spotted frogs breed early in the spring — often before the pond ice has disappeared. The breeding period is quite short and last 2 weeks at the most. The males station themselves along the shore and call with their heads just out of water. During mating the male clasps the female in pectorial amplexus. The females lay eggs in communal masses at the surface of the water, either freely floating or loosely tangled around emergent vegetation. The tadpoles usually transform in late summer and reach maturity in 4-5 years.

Wood frog found in the Columbia wetlands (Photo by Larry Halverson)

Mike Kerr, from Canmore, writes about the wood frog in his book The Canadian Rockies Guide to Wildlife Watching. It covers all the mountain national parks and there are a number of pages are dedicated to the Columbia Valley.

“The wood frog is the most terrestrial of frogs, so it may show up some distance from water. It is a truly Canadian frog, if ever there was one. Throughout Canada, the Wood frog is more widespread, found at higher elevations (up to 2,500 m), and encountered farther north than any other amphibian. In fact, it is the only amphibian that lives north of the Arctic Circle.

“Wood frogs survive our cold winter by burrowing under the forest floor. They also benefit from some nifty internal engineering, surviving temperatures as low as –6 degrees C with up to two-thirds of their body’s water in a frozen state. Wood Frogs pump large volumes of glucose into their cells; the glucose acts like antifreeze, allowing the water between the cells to freeze, while protecting the internal cell contents.”

For a full report on wood frogs see Wildlife Afield.

The annual Save the Frogs Day is a world-wide endeavour to educate and inspire people to take action to preserve the frog populations in their own neighbourhoods. Readers can find out more at http://www.savethefrogs.com.

Columbia Wetlands Stewardship Partners are interested in frog sightings in the Columbia Valley and invite you to participate in the BC Frogwatch Program. You can also take part Herpwatch, a survey for amphibians and reptiles in Banff, Kootenay, and Yoho National Parks.