Spatial distribution of prey captures by Boreal owl (Aegolius funereus) males providing for nestlings: importance of forest productivity

We studied home range use and forest habitat selection of four providing male Boreal owls (Aegolius funereus) by using VHF radio telemetry, and simultaneously recorded prey deliveries at the nest by using a video camera. The camera allowed prey identification and made it possible to assign a prey delivery to a prey capture location, i.e., the last observation fix before a delivery. Habitat classes were defined by forest productivity; high, medium, low and impediment. Habitat selection was estimated by first calculating the distance from each observation fix (N = 459) and from each random plot (N = 480) to the nearest patch of each habitat class, and then testing for differences using a generalized linear mixed model (GLMM). The owls foraged closer to areas of low, medium, and high productivity, and farther from areas of impediment, than expected by random. Prey captures in general were located closer to areas of high productivity and farther from areas of impediment than expected by random. Captures of shrews (Soricidae) in particular were closer to areas of high productivity than expected by random, which is in accordance with previous findings suggesting that the density of shrews increases with habitat productivity. Our novel method of combining radio tracking and video monitoring of prey deliveries to determine habitat specific prey capture in Boreal owls highlights the importance of forest habitat productivity.