Nesting requirements of the northern goshawk (Accipiter gentilis atricapillus) in southeastern British Columbia

• Main Author: Harrower, William Laughton
• Other Authors: Larsen, Karl W., Gregory, Patrick T.
• Format: Thesis
• Language: English
• Published: 2007
• Subjects: Goshawk; Nests; UVic Subject Index::Sciences and Engineering::Biology::Zoology; British Columbia; Canada; Accipiter gentilis; Northern Goshawk
• Online Access: http://hdl.handle.net/1828/2513

The identification of resources animals select provides valuable insight into the factors that limit populations and control distributions. My objective in this thesis was to examine how the northern goshawk (Accipiter gentilis atricapillus) selects resources during the nesting and fledging life-history stages. This work was conducted in southeastern British Columbia, Canada, from 1998 to 2006. Using Information-Theoretic techniques, I described the forest characteristics selected by goshawks when locating their nest sites within their breeding territories, and the forest characteristics selected by fledgling goshawks around the nest while they are still dependent on their parents for food. I found that goshawks select nesting sites with a relatively large amount of high canopy cover (>40%) forest within 200 m of the nest. The amount of high canopy cover forest remained higher than comparison points up to 1100 m from the nest, but goshawks also will select for forest openings relatively close to the nest (- 174 m). Fledgling goshawks selected for continuous areas of forest cover, particularly areas with higher amounts of forest between 40-80 years old within 525 m distance from the nest. Presumably, goshawks selected these younger stands in order to avoid predation. Fledglings also selected areas with more high canopy cover forest and areas without large amounts of recently-harvested forest (<10 years of age) stands within 525 m of the nest. Thus, the structural characteristics of forests required by goshawks for nesting are complex, and different competing characteristics are selected at different distances from the nest. Although goshawks do require mature forest stands with high canopy cover close to the nest, a greater diversity of forest types appears to be either tolerated or required as the distance from the nest increases. Additionally, limited evidence suggests that the movements of fledgling goshawks may be governed by a combination of forest structure and inter-familiar interactions.