Group differences in avian space use relate to group differences in resource use and demographic parameters. However, studies that consider year-round, intraspecific variation in the space use of noncooperatively breeding species are relatively rare. A greater understanding of factors relating to intraspecific variation in space use is especially important for managing human-subsidized predators, such as the Common Raven (Corvus corax). We hypothesized that sex, sociality, and the distribution of bonanzas of food should influence year-round space use by breeding and nonbreeding Common Ravens on the Olympic Peninsula of Washington State. We detected differences in space use between breeders and nonbreeders but not between the sexes. Breeders shared little space with their neighbors and displayed strong site fidelity, except in the fall and winter or after the death of a mate, when some breeding ravens moved extensively. Nonbreeders moved widely, were more gregarious, and their home ranges intersected a greater proportion of communal food resources than did those of breeders. Breeders shared little space with their adult neighbors, but they shared more space with nonbreeders when communal food resources fell within their territories. Pair bonds were broken only by the death of a partner, which in some cases was followed by extensive movements by the surviving adult prior to pairing with a new mate or settling in a new breeding territory. This study is the first to consider the space use of both nonbreeding and breeding Common Ravens in the same population simultaneously.
Vol. 114 • No. 3
Vol. 114 • No. 3