Beaver population helps battle drought (2/21/2008)

The presence of busy beavers can do more to preserve water resources than temperature, precipitation and other climate variables.

They may be considered pests, but beaver can help mitigate the effects of drought, and because of that, their removal from wetlands to accommodate industrial, urban and agricultural demands should be avoided when possible, according to a new University of Alberta study.

"Removal of beaver should be considered an environmental disturbance on par with in-filling, peat mining and industrial water extraction," said researcher Glynnis Hood, lead author on the study and a professor of environmental sciences at the University of Alberta's Augustana Campus in Camrose.

In examining how beaver influenced some of Alberta's wetlands in Elk Island National Park over a 54-year period, Hood and co-investigator professor Suzanne Bayley discovered that the presence of beaver and their dams increased the presence of open water by up to nine times.

Climate models predict the incidence of drought in parts of North America will increase in frequency and length over the next 100 years, and beaver will likely play an important role in maintaining open water and mitigating the impact, Hood said. Infilling and drainage of wetlands have increased to make way for urban and industrial expansion, and beaver colonies are being removed both inside and outside of protected areas, which means a continued loss of water resources, she added.

"In times of drought they may be one of the most effective ways to mitigate wetland loss," said Hood. "Some people believe climate is driving everything, but the presence of beaver has a dramatic effect on the availability of open water in an area. Beaver are helping to keep water in areas that would otherwise be dry."

When beaver were present, there was 60 per cent more open water in drought-stricken areas than in those same areas, during previous drought periods, when beaver were absent.

The study, published online recently in Biological Conservation, also found that temperature, precipitation and other climate variables were much less important than beaver in maintaining open water areas in the wetlands of the mixed-wood boreal forest.

The role of beaver in sustaining open water is critical for several reasons, said Hood. Flooding caused by beaver dams provides habitat and water resources used by land animals and amphibians, and even provides water for livestock. It can also recharge groundwater reserves.

The study was supported by funding from the Canadian Circumpolar Institute, Alberta Sport, Recreation, Parks and Wildlife Foundation and the Friends of the Elk Island Society.

Note: This story has been adapted from a news release issued by the University of Alberta

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