Beavers help out young frogs

Beavers are a boon to the environment: Their dams create ponds that provide homes for birds, amphibians, and other critters. Now scientists have found that beavers also aid their wetland companions by digging canals that young frogs use to hop from ponds to forests.

The canals, which allow beavers to transport branches and hide from predators, can stretch over hundreds of meters. But “the effect of canals on wetland ecosystems has received little study,” the researchers write in Animal Conservation. If the canals help beavers move around, they wondered, do they also help amphibians? For instance, wood frogs are born in ponds, but they must find their way through meadows to forests where they can spend the winter.

The team investigated the question at Miquelon Lake Provincial Park in Alberta, Canada, where beavers have dug canals more than 200 meters long. The researchers installed fences by canals at six ponds and checked them for wood frogs during the summers of 2011 and 2012. They also visited 14 ponds and scanned the areas with and without beaver canals for wood frogs.

The fences caught 4,473 young frogs and 279 adult frogs, the study authors report. The closer a fence section was to the canal, the more young frogs they found. In their surveys of 14 ponds, the researchers also spotted six to nine times more young wood frogs on canals than along pond shorelines without canals.

Wood frogs probably like the canals because they provide a source of water and a refuge from predators. The researchers noticed frogs taking cover under the plants on the canal banks, and they observed other amphibians such as western tiger salamanders near the canals as well. By connecting patches of habitat, the team says, beavers could be valuable allies in amphibian conservation. Roberta Kwok | 30 October 2014

Source: Anderson, N.L., C.A. Paszkowski, and G.A. Hood. 2014. Linking aquatic and terrestrial environments: can beaver canals serve as movement corridors for pond-breeding amphibians? Animal Conservation doi: 10.1111/acv.12170.

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