. The Canadian field-naturalist. 1998 Notes 525. Figure 1. The captures of small mammals from 184 trap-nights. and their relative abundances. Trapping success was quite high, almost 20% (35 animals, 184 trap nights; Figure 1), with Meadow Voles {Microtus pennsyl- vanicus) being the most abundant (46% of all captures). Other captures, in order of decreasing abundance were Red-backed Vole, Clethrionomys gapperi; Woodland Jumping Mouse, Napaeozapus insignis; Masked Shrew, Sorex cinereus, and Smoky Shrew, (Figure 1). Breeding Evidence We came across the first Northern Hawk Owl opportunist
. The Canadian field-naturalist. 1998 Notes 525. Figure 1. The captures of small mammals from 184 trap-nights. and their relative abundances. Trapping success was quite high, almost 20% (35 animals, 184 trap nights; Figure 1), with Meadow Voles {Microtus pennsyl- vanicus) being the most abundant (46% of all captures). Other captures, in order of decreasing abundance were Red-backed Vole, Clethrionomys gapperi; Woodland Jumping Mouse, Napaeozapus insignis; Masked Shrew, Sorex cinereus, and Smoky Shrew, (Figure 1). Breeding Evidence We came across the first Northern Hawk Owl opportunistically, alerted to its presence by its vocal- ization. Upon returning to the site, we again found the bird and were able to spend time observing it. On two occasions (separated by about 20 min) the bird caught a prey item (likely M. pennsylvanicus) and flew directly away from the foraging area. Upon capturing prey intended for its mate or young, male Hawk Owls are known to make a rapid, direct return to the nest (Jones 1987). We took a bearing on the bird's direction and started to track it to what we assumed was a nest site. Vocalization of what was initially believed to be nestlings aided in the detec- tion of the nest. The calls were actually those of the attending adult who greeted her mate on each arrival. The habitat at the nest site was identical to that of the previously described foraging site. With both adults present and showing aggression (bill-snapping, inter- ception-flying) locating the nest tree was relatively easy. The nest was in a conifer snag (dbh = m) bro- ken off at a height of 9 m. The base of the cavity ( the height of the nest) was 6 m from the ground and continued to the top; much of the interior of the nest was exposed from the level of the nest to the top of the tree ( a chimney-style cavity with half of the wall missing). As a result, the young owls were visi- ble, though only as an amorphous mass of grey down with some flight feathers
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