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The Beav


Springtime has come; 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 under water (thanks to a second transparent "eyelid"). They can also 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 qualities.


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 a 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.


But some people view beavers negatively. From an economic point of view, 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 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. They also 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, 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.


Upcoming Events:

Saturday, June 1, 7 a.m. — Bird Walk . Meet at the bottom of Lorimer Road near the entrance to the Catholic Church. Novices and newcomers welcome. Call Michael Thompson for details.

Wednesday, June 5, 6:30 p.m. Nature Walk at Shadow Lake Demonstration Forest . Park one kilometre north of the Green River rail crossing at the Ministry of Forests parking lot (east side of the highway). We’ll then convoy slightly north. Highlights include transitional ecosystems, the big slide, and human history (e.g., the Pemberton Trail). Call Mitch Sulkers for details.

Saturday, June 8 — Pemberton Bird Walk at One-Mile Lake, 8 a.m. Mark this great event on your calendar — last year we saw almost 50 species of birds (and lots of interesting flowers) in two hours! The walk leaders are the five crack birders from the annual Breeding Bird Survey. Meet in the parking lot. Call Bob Brett for details.

Saturday, June 8 — Breeding Bird Slide Show, 6:30 p.m. The five expert and very funny birders here for the 27th annual Breeding Bird Survey will tell us what it’s all about. Everyone welcome. We’re currently confirming a venue – watch this space next Friday for details, or call Bob Brett.


Written by: Cathy Conroy


#Fauna

Whistler Naturalists

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