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We assessed 4 methods of attaching transmitters to nestling Common Ravens (Corvus corax) in Grand Teton National Park, Wyoming, in preparation for a larger telemetry study. The attachment types included backpack style with a cross-chest harness, rump mount (“figure-8”), necklace, and tarsal mounts. We tested 2 to 5 transmitters of each attachment type and recorded the ease of attachment, agitation of the ravens (from the nestling stage through the post-fledging dependence period) caused by the transmitters, and any noticeable abrasions caused by the attachment. We preferred the tarsal mount attachment because the transmitters can be placed on the bird early in the nestling stage and 1 person can attach it quickly. We did not prefer the other methods. The necklace mount became “bridled” between the bird's upper and lower mandible and/or fell off. Backpack and rump mounts required extensive fitting time, and we felt they should not be used until the nestlings had attained maximum growth, reducing the window of time for attachment.
We report on 1153 winter prey items eaten by 11 Barred Owls (Strix varia) from 6 areas in west-central Montana. Small mammals dominated the diet, representing 98 to 100% of the frequency of prey eaten by each owl. Of the small mammals, voles (Microtus) were clearly the most numerous prey group, representing 97.6% of all prey. Within Microtus, the Montane Vole (Microtus montanus) was the most numerous species eaten at 5 areas, and the Meadow Vole (M. pennsylvanicus) was the most numerous species eaten at 1 area. Pellet length × width for 4 Barred Owls averaged 61.4 × 24.5 mm. Because of the adaptability of Barred Owls and the overlap of their range with that of the Spotted Owl (S. occidentalis) in the northwestern United States, future dietary comparisons between seasons may also help elucidate the comparative ecology of these congeners as conservation issues arise.