Naturespeak 

Hummers are back

Whistler Naturalists

Summer is on its way; the hummingbirds are back, the bears are feasting on skunk cabbage and grass, and our largest rodents (beavers, Castor canadensis ) are very busy.

Walking the valley trails near any waterway nearly always results in signs of recent beaver activity: newly felled trees, stripped shrubs, fresh dams, flooded ponds. Over the winter, deep snow cover prevented any home and pond maintenance activity for these aquatic animals, so now they need to repair and rebuild their dams and lodges and prepare for the birth of this year’s kits. All of these repairs mean the beavers need significant amounts of building materials in the form of trees and limbs. The results of their activity are obvious throughout the valley.

Beavers typically live approximately 15 years in the wild and are monogamous, mating for life or "remarrying" upon the death of their mate. Beavers typically share their home pond and surrounding habitat with several years’ offspring until the youngsters move on to establish their own territories – sometimes nearby, or even several hundred kilometres from their parents.

Beavers are remarkable water-dwelling mammals, perfectly suited to life in and around water. They can close their eyes and still see underwater (thanks to a second transparent "eyelid"), they can plug their nostrils and ears with little fleshy flaps which they use when diving under water. They can easily hold their breath for a good 15 minutes – and during these longer dives blood is diverted from their cold paws and tail to their brain, maximizing oxygen flow where it is most needed. Of course beaver fur is well known for its nearly perfect waterproof and heat retention abilities.

Somewhat awkward on land, once in the water beavers are powerful and expert swimmers. Their flattened scaly and muscular tail and their large hind feet are used for underwater propulsion and steering. They also use their paddle-like tails for signalling – there’s nothing quite like the heart-stopping warning slap of a beaver’s tail during a peaceful evening canoe paddle on a quiet lake. Anyone who has heard that gun-shot-like sound knows how effective the signal is at alerting anything nearby of intrusion into a beaver’s home territory.

Some in society view beavers negatively. From an economic standpoint, damage incurred from beavers by "nuisance activity" can be costly: damaged trees, unwanted flooding of lands and roadways, and the damming of culverts usually make for unhappy landowners. It is estimated that negative economic impacts from beaver activity annually exceed the value of their harvested pelts in the United States (which is in the millions). So what? I argue that the ecological benefits from beaver activity far outweigh any perceived or real negative economic impacts in the short-term.

Other than humans, no other animal in North America is capable of modifying their environment more than the lowly beaver. Beaver ponds conserve spring runoff and ensure season-long constant stream flows, and diminish downstream flooding – thereby conserving productive and valuable soils. Water-loving plants thrive in and around beaver ponds, and these plants in turn provide food and shelter for a variety of animals. Beaver ponds help raise and maintain water tables, which enhances adjacent plant growth and production. Invertebrate production and diversity increases in the ponds as well. All of these have clear and direct benefits to countless other species such as songbirds, ducks, fish, eagles and osprey, small and fur-bearing mammals, owls, deer, moose, bears, and – last but not least – humans.

When the beaver disappears, their dams fall into disrepair, their ponds vanish, water tables fall, stream and pond side vegetation dies, and the animals that depend on that habitat leave or become extinct.

What would we do without them? Reintroduce them, of course. In fact, the beneficial effects of beaver activities have been clearly recognized in North America. Once trapped to the brink of extinction in the early 1900s, thanks to reintroduction programs and improved management beavers are now found throughout most of their former range.

Check out the complex of beaver lodges and ponds along the Valley Trail near the Chateau Golf Course on Horstman Creek, between the railway tracks and Rainbow Beach, or in a number of other spots. Beavers are most active in the evening and at night. Sit quietly and watch for them gathering building materials, or looking for green plants to eat. Or just enjoy the beautiful wetland environment created by their industrious damming projects.

Sightings and Memberships: NatureSpeak is prepared by the Whistler Naturalists. To become a member, write an article for the Naturespeak column or to report noteworthy sightings of mammals, birds, or other species, contact Amber at naturespeak@telus.net.

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