Prince Island in Calgary AB Canada sits smack in the middle of the Bow river which starts in the Rockies and ultimately empties in the Hudson Bay. It is a treasured slice of nature in the middle of the city and the site of many festivals and events. It also a roadstop along the highway for many a dispersing beaver when winter thaws enough to let them be on their way. In 2013 the area suffered such dramatic flooding that no one was worrying about beavers. Now, they have found the time.

Beavers causing Calgary tree troubles

“We’re trying to determine how many are out there,” said Tanya Hope, parks ecologist with the City of Calgary. What has definitely changed as a result of the 2013 flood is how Calgary’s rivers flow and where the beavers are congregating as a result of fast and slow sections of the Bow and Elbow.

This year, wildlife experts say the water-loving animals are far more concentrated than before, and appear to be hoarding themselves in different areas of the city than before the flood, which basically wiped the river map clean. “The lodges are much closer and they seem to be clumping together,” said Hope.

“On Prince’s Island, for example, where we used to have just one beaver lodge we now have three.” That means up to 18 beavers — including adults, older offspring and kits — can potentially be found gnawing down trees in the area.

That’s a lot of teeth — and because many of the areas impacted have no prior history of beavers, there’s no wire in place to protect the trees from this post-flood population, which if its anything like the beaver community prior to 2013, could number in the 200 range.

The result is extensive devastation, with reports being filed with Calgary 311 of up to 20 and 30 trees being felled in a given area.

So they think all that flooding flooded the beaver population too, because now new lodges are cropping up everywhere and more trees are getting eaten. I mean supposedly more. I haven’t seen an actual graph of how many trees usually get felled in the spring. (I mean these are government employees, they could do that.) But the article begs the question, does flooding make beavers breed more, or tolerate neighbors more?

Dr. Science says ‘no’.

Then how do you explain the new lodges? Appearing in clusters around the river. Apparently there used to be just one on the island and now there are three!

Dr. Science crosses his legs and gets ready for a long answer.  “New lodges don’t mean new beavers.” He explains. “Just because a new lodge appears doesn’t mean a new family has moved in. Just like a new home on the block doesn’t mean the neighborhood has increased. Families move from one home to another just like humans do. Especially after huge flooding events that can fill a lodge with mud or parasites. Also, teenagers  sometimes build ‘frat houses’ where they can live on their own but still close enough to mom and dad to get rescued when they need it.”

In the bad old days, the city might have tried to protect the trees by eradicating the buck-toothed pests, but in this enlightened age, Calgary does what it can to live with the animals, destructive trapping being a last resort for forests in danger of being ruined forever.

Beavers are now understood to be a healthy part of an ecosystem, and their activities can help humans too — such as the dam at Prince’s lsland, that helped protect a storm water pond from being swept away during the big flood.

Instead of a beaver cull, trees are wrapped with wire, pipes are built under known dams so the city doesn’t have to knock them down, and Calgary is currently testing a new beaver-deterrent spray that can be applied to a lot of trees in a very short time.

And on Tuesday, the city released a video for private property owners along the rivers, showing them how to wrap their trees to prevent loss to the roving rodents, which include so-called “transient beavers” which are just passing through the city via the rivers.

To keep the beavers from starving, the city only protects 80% of trees in a healthy forest, leaving easily replaced and regrown timber for food and rodent construction projects. Those landscape-altering endeavours are what made Hope go from just studying Calgary’s beaver population, to really admiring the animals for their cleverness and ingenuity.

“I think beavers are amazing, and they are the only species apart from humans that can completely change the landscape around them,” she said.

“We definitely want to work to keep them here in Calgary.”

Dr. Science is happy about that.