Habitat utilization and population densities of the amphibians of northeastern Alberta

Abstract

During 1976 and 1977 a survey of the herpetofauna of boreal forest habitats of northeastern Alberta was undertaken. The wood frog (Rana sylvatica) was the most abundant and widespread species and was collected at 24 of 25 sites examined. Boreal chorus frogs (Pseudacris triseriata maculata) and Canadian toads (Bufo hemiophrys) were common but found at less than half of the study sites. Canadian toads also spawned in flowing water and lake margins. All species had metamorphosed by early August. Wood frogs metamorphosed at a mean snout-vent length of 17.2mm, Canadian toads at 12.4 mm and boreal chorus frogs at 13.7 mm. Spawning for each of these species probably does not occur until individuals are in the third summer of life. Population densities of wood frogs, boreal chorus frogs and Canadian toads reached estimated maxima of 19.6, 2.3 adn 12 per 1000 m2 during 1977. Maximum densities of all species were found within 50 m of the nearest waterbody in moise habitat vegetated by sedges, grasses, horsetails, willows, and poplar. Lower densities were found in upland mixed woods and no anurans were found in dry areas with sandy substrate and jack pine forest. Other amphibain and reptiles species were not encountered.