Volume 126, Issue 2, 2009, Pages 300-309
a
Environmental and Life Sciences Graduate Program, Environmental
Science Centre, Trent University, 1600 West Bank Drive, Peterborough, ON
K9J 7B8, Canada
b Biology Department, Environmental Science Centre, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada
c Ontario Ministry of Natural Resources, 659 Exeter Road, London, ON N6E 1L3, Canada
b Biology Department, Environmental Science Centre, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada
c Ontario Ministry of Natural Resources, 659 Exeter Road, London, ON N6E 1L3, Canada
Abstract
We evaluated
hypotheses explaining risk of predation by American Black Bear (Ursus
americanus) at 418 Yellow-bellied Sapsucker (Sphyrapicus varius) and
Hairy Woodpecker (Picoides villosus) nests, on the basis of nestling
begging and nest-site habitat features in Algonquin Provincial Park,
Ontario. Ninety-three percent of Yellow-bellied Sapsuckers in stands
dominated by Sugar Maple (Acer saccharum)
nested in Sugar Maple or American Beech (Fagus grandifolia) trees that
were dead or in declining health, whereas 86% of Yellow-bellied
Sapsuckers in stands dominated by aspen (Populus spp.) nested in Quaking
Aspen (P. tremuloides) that were in declining health. Black Bears
depredated 17% of 315 nests of Yellow-bellied Sapsuckers in Sugar Maple
stands, which accounts for 71% of all Yellow-bellied Sapsucker nest
failures. Only 1 (2%) of 46 Hairy Woodpecker nests in the same Sugar
Maple stands was depredated by a bear. None of 51 Yellow-bellied
Sapsucker nests in aspen stands was depredated. In Sugar Maple stands,
daily nest survival of Yellow-bellied Sapsucker nests was lowest when
nestling begging calls were loudest and carried the farthest, in more
recently harvested stands, and in trees other than American Beech
(mostly Sugar Maple). Nest substrates were hardest at Hairy Woodpecker
nests, followed by successful Yellow-bellied Sapsucker nests in American
Beech and Quaking Aspen; Yellow-bellied Sapsucker nests were softest in
stands that had been harvested within the past 30 years. Our study
suggests that the risk of predation by American Black Bears at
woodpecker nests is a combined function of nestling begging calls, which
attract bears to the nest, and nest habitat characteristics, which
influence accessibility to the interior of the cavity. © 2009 by The
American Ornithologists' Union. All rights reserved.
Author keywords
American Black Bear; Cavity-nest site selection;
Nestling begging calls; Sphyrapicus varius; Tree harvest; Ursus
americanus; Yellow-bellied Sapsucker
Indexed keywords
GEOBASE Subject Index: bear; bird; deciduous tree; habitat selection; nest predation; nest site; nestling; predation risk; site selection
Regional Index: Algonquin Provincial Park; Canada; North America; Ontario [Canada]
Species Index: Acer; Acer saccharum; Fagus; Fagus grandifolia; Picoides villosus; Populus; Populus tremuloides; Sphyrapicus varius; Ursus americanus