Abstract and Summary

We followed the behavioral development of 8 young American beavers (Castor canadensis) in their natural environment. The behavioral development of wild beaver kits living in a familial unit with one adult pair and yearlings can be divided in three distinct phases. 1. The first 4–5 weeks during which the neonates were confined to the lodge were characterized by physical maturation and a very rapid development of locomotion, alimentation, care of the fur, and social behaviors. 2. The next phase extended from first emergence from the lodge to the next spring. Development of ability to stay submerged, exploration of the aquatic part of the home range of the family and refinement of skills characterized this period. No new behavior patterns appeared during this phase. 3. The last period extended from about 10 months to the dispersal of the animals when they were around 2 years old, and was marked by the development of building behaviors and of food gathering. Comparisons with the development of captive beavers suggested that in general, the environmental conditions did not significantly alter the developmental pattern of young beavers. Comparisons with other accounts on the development of some other rodents indicate that beavers are most similar to some precocial hystricomorphs that exhibit a slow rate of development.