Habitat Factors Influencing Beaver Dam Establishment in a Northern Ontario Watershed

Beaver (Castor canadensis) dam-site selection studies traditionally have relied on plant composition. To understand how habitat factors influence dam establishment, we compared 9 plant composition and size categories and their spatial distribution with 4 physical features at 15 active dams, 15 abandoned dams, and 12 no-dam sites. To establish pre-dam vegetation densities, plots downstream and upstream from impoundments were averaged. We found beaver relied on both physical (upstream watershed area and stream cross-sectional area) and vegetation (shoreline concentrations of woody plants with diameters 1.5-4.4 cm) factors in choosing dam sites. The model designed by McComb et al. (1990) was not effective in predicting dam sites in northern Ontario, therefore, we recommend that managers test the model's regional accuracy in determining site locations.