Beaver (Castor canadensis) as a surrogate species for conserving anuran amphibians on boreal streams in Alberta, Canada

We explored the use of beaver (Castor canadensis) as a surrogate species for amphibian conservation on small (1st-4th-order) streams in the Boreal Foothills of west-central Alberta. Anuran call surveys indicated that beaver create breeding habitat for the boreal chorus frog (Pseudacris maculata), wood frog (Rana sylvatica) and western toad (Bufo boreas). No calling males of any species were recorded on unobstructed streams. Wood frog, the most abundant species, exhibited high rates of juvenile recruitment on beaver ponds. Pitfall traps captured more wood frogs on beaver ponds versus unobstructed streams, and most individuals (84%) were young-of-year. Abundance of young-of-year was strongly correlated with percent landscape occupied by beaver ponds indicating that anurans captured along streams originated in beaver ponds. Based on a novel combination of a digital elevation model and aerial photographs examined with GIS, statistical models showed that the probability of beaver pond occurrence on streams was positively associated with stream order and dependent on the interacting effects of distance to nearest forestry cutblock and availability of beaver foods (Populus spp.). We propose that the distribution and abundance of beaver ponds could be determined over large areas quickly and inexpensively by remote sensing and used to identify and monitor amphibian habitat, and possibly, populations. This work establishes the pre-eminence of beaver-created wetlands as amphibian habitat in the Boreal Foothills and that the incorporation of dam-building patterns into forest management strategies could aid amphibian conservation.