Comparative Morphology Among Three Northern Populations of Breeding Cooper's Hawks
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Date
2006Author
Rosenfield, Laura J.
Publisher
University of Wisconsin-Stevens Point, College of Natural Resources
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Show full item recordAbstract
The Cooper's Hawk (Accipiter cooperii) is designated as threatened, rare, or species of concern by several state and provincial governments in the United States and
Canada. However, informed management of this species across its broad North
American range is hampered by a paucity of data on its nesting biology and biogeographic distribution. Conservation agencies currently cannot identify individual
populations or understand the extent of eco-variation in phenotypes that may exist in
different Cooper's Hawk breeding populations across the continent. I studied differences
in morphological characteristics of nesting Cooper's Hawks in the eastern deciduous
forests of Wisconsin, isolated drainage woodlands in short grass prairies of North Dakota,
and the coniferous forests of British Columbia, Canada; a longitudinal span of 2700 km.
I measured body mass, wing chord; .tail length, tarsus diameter, hallux length, and culmen
length in captured nesting adults. In this study, Cooper's Haw~ populations exhibited
significant variation in several of these morphological across sites including body mass;
when body mass was used as a covariate in ANCOV A several morphological
characteristics still differed among study sites. These data suggest that there is little gene
flow among populations so discernable morphological differences appear to persist. I
speculate that these differences are adaptive and, in part, the result of geographic
isolation, where diets, migratory behavior, and/or structural characteristics of nesting
habitats vary across landscape types.