Wild St. Albert busy, busy beavers
Wooly lumberjacks build homes for many
By: Kevin Ma
| Posted: Wednesday, Oct 17, 2012 03:16 pm
Name: Castor canadensis
Appearance: big brown rodent with large, flat tail and buck teeth
Commonly seen: pushing branches through the Sturgeon, chewing trees
Often confused with: muskrats which are way smaller
Fun fact: prehistoric beavers grew up to three metres long and weighed about 360 kilograms
It was a hot day in August seven years ago. I had just located the end of the Sturgeon River, and stood on its banks as it cut through a verdant, emerald valley. All was quiet and at peace.
Suddenly, a shot rang out. CRACK! After a few confused moments, during which I tried to find the unseen hunter and give him a piece of my mind, it happened again. CRACK!
Eventually, I realized the truth; this was no lone gunman, but a busy beaver, smacking its tail against the water as it dived into the Sturgeon.
Beavers are everywhere in the Sturgeon, and are one of the most influential engineers on its waters.
The beaver is the largest rodent in North America, according to Lee Foote, a wildlife biologist at the University of Alberta. “There are some on record that are over 100 pounds (45 kilograms).”
Beavers were almost wiped out by the 1950s due to overharvesting, Foote notes, but are now flourishing after being reintroduced from havens such as Elk Island National Park.
Beavers look like giant muskrats, Foote continues, except for their tails, which are large and flat instead of skinny. “If you see a big animal pushing a stick (in the water), it’s probably a beaver.”
Beaver tails are huge, according to Hinterland Who’s Who, and can be up to 30 centimetres long, 18 wide and four thick. The tail acts as a rudder in water and a prop on land, enabling them to stand upright. Beavers also use it to warn others, slapping it against the water to produce a pistol-like crack.
Contrary to popular belief, Foote notes, the tail is not used as a weapon and is not used to carry mud. “It’s also not very edible.”
Trappers prized the beaver’s fur back in the day, Foote says, as it was very warm and waterproof. Beavers use their comb-like back claws to smear a foul-smelling substance called castoreum (which is also used in many perfumes) through their fur to make it shiny and water-repellent.
The beaver swims with its webbed back feet, Foote says, and grabs branches with its agile front claws.
Beavers chew through those branches with their big teeth. The beaver’s upper teeth have softer enamel at the back than the front, Foote says, and grind against the bottom ones with every bite. “It’s like sharpening a chisel point all the time.”
Most beavers will be frantically filling their winter food caches by now, Foote says, making sure to pile the quick-rotting fine twigs on top and the sturdy logs on the bottom. “They eat the tender, delicious stuff first.”
This behaviour, plus the massive dams they build in the summer, is where beavers get their industrious reputation. Beavers here must build dams to create deep pools of water in which to swim and store food in the winter, Foote notes. “They really have to work hard to make ends meet.”
Beavers in the southern U.S. are lazy by comparison, Foote says — they have plenty of food year round, and don’t have to build lodges. “You see them sleeping for hours of the day on a log.”
Beavers can cause trouble for humans, says City of St. Albert arborist Kevin Veenstra, especially when they clog outlets with dams or topple trees over paths.
There are about 10 beavers in the Sturgeon in St. Albert right now, he says, plus many more around Carrot Creek. The city loses about 20 trees a year to beavers despite the use of trunk-protecting wire wraps.
“They definitely have an affinity for poplar and willow,” Veenstra says, and can chew through a small tree in an hour. He recalls one that was so engrossed in dragging a maple across the trail near Butterfield Cres. that he had to stop his vehicle to let it pass.
The city will occasionally move or shoot beavers if they cause too many problems, Veenstra says, but generally leaves them alone unless they threaten infrastructure.
Beavers are actually a big benefit to the Sturgeon, Veenstra says, as they keep its water levels high.
Alberta was a much drier place in the absence of the beaver, Foote says. Their dams enhance groundwater recharge and create homes for moose, muskrats and bufflehead ducks. “They are an ecosystem engineer.”
I’d like to think that that beaver seven years ago was slapping its tail to say hello, but I’m pretty sure it was saying something like, “Get off my river!” I did what Veenstra says anyone should do if they encounter a beaver: I sat back and gave it its space.