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Beaver (Castor canadensis) occupy a variety of habitats in North America, but prefer Aspen (Populus trernuloides) and willow (Salix spp.) for food and construction materials. Beaver landforms, such as dams, can cause many problems for landowners, resulting in varied management efforts, such as dam dismantling and Beaver removal. The goal of this study was to compare the density of Beaver activity along Camrose Creek, Alberta, among a variety of habitats and management intensities. Along this 35 km creek there were an average of 0.46 food caches/km, 0.57 lodges/km, and 3.06 dams/km (of which 1.66/km were altered by people and 1.40/km were unaltered). There were more caches, lodges, and unaltered dams in Trembling Aspen forests compared to other habitats. Areas with some management had more food caches and either altered or unaltered dams than areas with no management. [ABSTRACT FROM AUTHOR]

Shallow open water wetlands provide critical habitat for numerous species, yet they have become increasingly vulnerable to drought and warming temperatures and are often reduced in size and depth or disappear during drought. We examined how temperature, precipitation and beaver (Castor canadensis) activity influenced the area of open water in wetlands over a 54-year period in the mixed-wood boreal region of east-central Alberta, Canada. This entire glacial landscape with intermittently connected drainage patterns and shallow wetland lakes with few streams lost all beaver in the 19th century, with beaver returning to the study area in 1954. We assessed the area of open water in wetlands using 12 aerial photo mosaics from 1948 to 2002, which covered wet and dry periods, when beaver were absent on the landscape to a time when they had become well established. The number of active beaver lodges explained over 80% of the variability in the area of open water during that period. Temperature, precipitation and climatic variables were much less important than beaver in maintaining open water areas. In addition, during wet and dry years, the presence of beaver was associated with a 9-fold increase in open water area when compared to a period when beaver were absent from those same sites. Thus, beaver have a dramatic influence on the creation and maintenance of wetlands even during extreme drought. Given the important role of beaver in wetland preservation and in light of a drying climate in this region, their removal should be considered a wetland disturbance that should be avoided. [Copyright &y& Elsevier]

Borrow pits, dug by industry to provide substrate for infrastructure such as roads and well sites, are prevalent throughout the boreal forest of western Canada yet little is known about their use by wildlife. During field surveys in Rainbow Lake, Alberta, we found that beavers (Castor canadensis) used inundated borrow pits extensively for foraging and over wintering, suggesting that borrow pits increase beaver populations above their natural carrying capacity in industrial landscapes. We visited a random sample of 90 borrow pits in the field and categorized them as having active beaver lodges with caches (n = 16), inactive lodges (n = 13), cutting (n = 29), no activity (n = 13), or as not inundated or not a borrow pit (n = 19). We then used this sample to model where beavers established lodges versus where they were inactive or were only cutting. We found that borrow pits with active lodges had unique characteristics from other pits in our sample and were closer to streams, marshes, and swamps and had greater vegetation concealment from roads. These models can be used by managers to develop methods for increasing or decreasing the abundance of beavers living at borrow pits. Wildlife managers might want to use borrow pits to increase beaver abundance because of the positive effects beavers can have on ecosystems and because beavers are an important source of food for boreal carnivores. For example, we found that wolverines (Gulo gulo) used borrow pits as hunting grounds for beavers and one wolverine denned within a beaver lodge at a borrow pit. Conversely, managers might want to reduce beaver populations living at borrow pits because of the damage that beavers can cause to infrastructure and because subsidized beaver populations might alter predator-prey dynamics. To accomplish this, we suggest reducing available vegetation around borrow pits, isolating new borrow pits from natural beaver habitats, digging borrow pits where there is less chance of having surface water, filling in borrow pits with substrate, or not creating borrow pits and using a centralized gravel pit or mine for substrate. • We found beaver activity at the majority of borrow pits in Rainbow Lake, Alberta. • We modeled habitats associated with borrow pits where beavers established lodges versus other beaver activities. • Active beaver colonies were closer to marshes, swamps, and streams and had a tall vegetation buffer between the borrow pit and road. • Beavers occupying borrow pits subsidized prey for wolverines and other carnivores. [ABSTRACT FROM AUTHOR]