Beavers busy setting up shop
I thought maybe they were cut down, but I took a closer look and it definitely looks like beaver teeth marks.”
Jeffrey Bergman, Western Pennsylvania Conservancy director of community forestry, hadn’t heard about the tree loss until he picked up the phone Wednesday afternoon. He was on site in a half-hour.
“In this location we removed invasive nonnative plant species like bush honeysuckle and Japanese knotweed,” he said. “We planted native species. Part of the project is beautification, but also to introduce native species to improve the habitat for animals. I didn’t think we’d be quite this successful in improving the habitat for beavers.”
Mr. Bergman noticed that the only trees that had been touched were the newly planted native redbuds.
The conservancy has worked with the Sports and Exhibition Authority since 2016 to put about 1,800 trees in the ground at North Shore Riverside Park, the South Side, Mount Washington and the Downtown area. By the end of spring, he said, the conservancy will have planted some 30,000 trees throughout Allegheny County since 2010.
“Trees have so many benefits,” said Mr. Bergman. He glanced back at the row of pointed stumps.
“We haven’t lost quite this many [at one time] in the past. Usually it’s one here and one there. But to lose 16 trees out of 1,800 and lose them to a native species? I don’t consider this to be a tragedy.”
Conservancy staff and partner organizations will likely meet soon, he said, to discuss issues including possible riverbank erosion caused by the tree loss.
Growing up to 60 pounds, Castor canadensis is North America’s largest rodent. Extirpated from the Three Rivers as early as 1840, beavers were virtually gone from the state by the end of the 19th century. In 1903 Pennsylvania passed laws protecting the species and in 1917 the Game Commission began importing and transplanting beavers. Today, all Pennsylvania beavers are the progeny of forebears imported from Wisconsin and Canada.
A pair were spotted by runners on the Monongahela River shoreline near East Carson Street about 10 years ago.
“It’s nice there is this comeback,” said Henry Kacprzyk, a biologist at the Pittsburgh Zoo and PPG Aquarium. “It means the rivers are clean enough to support them, even in the center of the city. But they’re not returning to a natural environment.”
Beavers are considered a “keystone species,” said Mr. Kacprzyk, because they are one of the few animals that impact every plant and animal around them.
“Their dams back up water creating new aquatic environments, and plants, insects, birds and other animals have to adapt,” he said. “Over many years the slow-moving ponds collect silt, which fills in and creates meadows and again everything has to adapt. … It will be interesting to see how beavers do here.”
Beavers have few predators, so Pennsylvania keeps populations in check through regulated fur-bearer trapping seasons.
Animal control units have been used to relocate problem beavers.
Generally living in monogamous pairs, beavers produce litters of one to six kits in March inside the lodge, traditional or underground. Kits stay for two years sharing the space with their parents and younger siblings.
“In winter when there’s no foliage, they’ll fell trees and push the branches into the mud underwater to save them to use for food,” said Mr. Kacprzyk.