Urban beavers at home in city

PITTSBURGH — A minor ecological setback took a bite out of Western Pennsylvania Conservancy’s plans to plant thousands of native-species trees throughout Pittsburgh. Another native species, beavers, felled a row of recently planted trees at North Shore Riverfront Park in the shadow of Heinz Field.

Pedestrians walking the Three Rivers Heritage Trail noticed the missing trees Tuesday and Wednesday. On the bank of the Ohio River, between the Mr. Rogers statue and Carnegie Science Center, 16 pointed stumps are what’s left of a row of young 4-inch diameter redbud trees planted by Conservancy staff last fall. No tree trunks, no branches. Just distinctive gnaw marks about 16 inches above the ground, a handful of wood chips surrounding each stump and one pair of beaver footprints pressed into the mud near the riverbank.

The culprits weren’t trying to dam the Ohio River. Like muskrats, some beavers live in holes dug into mud banks with one entrance above the water surface and another below.

“I walk by here every day for work but (Tuesday) night was the first time I noticed that all these trees were knocked off,” said Zeb Carbaugh of McCandless. “At first 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 onsite in a half hour.

“In this location we removed invasive nonnative plant species like bush honeysuckle and Japanese knotweed. 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.”

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, Mt. 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 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.”