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Stable occupancy by breeding hawks (Buteo spp.) over 25 years on a privately managed bunchgrass prairie in northeastern Oregon, USA

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Title Stable occupancy by breeding hawks (Buteo spp.) over 25 years on a privately managed bunchgrass prairie in northeastern Oregon, USA
Names Kennedy, Patricia L. (creator)
Bartuszevige, Anne M. (creator)
Houle, Marcy (creator)
Humphrey, Ann B. (creator)
Dugger, Katie M. (creator)
Williams, John (creator)
Date Issued 2014-07-16 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Cooper Ornithological Society and can be found at: http://www.bioone.org/loi/cond.
Abstract Potential for large prairie remnants to provide habitat for grassland-obligate wildlife may be compromised by
nonsustainable range-management practices. In 1979–1980, high nesting densities of 3 species of hawks in the genus
Buteo—Ferruginous Hawk (Buteo regalis), Red-tailed Hawk (B. jamaicensis), and Swainson’s Hawk (B. swainsoni)—were
documented on the Zumwalt Prairie and surrounding agricultural areas (34,361 ha) in northeastern Oregon, USA. This
area has been managed primarily as livestock summer range since it was homesteaded. Unlike in other prairie
remnants, land management on the Zumwalt Prairie was consistent over the past several decades; thus, we predicted
that territory occupancy of these 3 species would be stable. We also predicted that territory occupancy would be
positively related to local availability of nesting structures within territories. We evaluated these hypotheses using a
historical dataset, current survey and habitat data, and occupancy models. In support of our predictions, territory
occupancy of all 3 species has not changed over the study period of ~25 yr, which suggests that local range-management
practices are not negatively affecting these taxa. Probability of Ferruginous Hawk occupancy increased
with increasing area of aspen, an important nest structure for this species in grasslands. Probability of Swainson’s Hawk
occupancy increased with increasing area of large shrubs, and probability of Red-tailed Hawk occupancy was weakly
associated with area of conifers. In the study area, large shrubs and conifers are commonly used as nesting structures
by Swainson’s Hawks and Red-tailed Hawks, respectively. Availability of these woody species is changing (increases in
conifers and large shrubs, and decline in aspen) throughout the west, and these changes may result in declines in
Ferruginous Hawk occupancy and increases in Swainson’s Hawk and Red-tailed Hawk occupancy in the future.
Genre Article
Topic Ferruginous Hawk
Identifier Kennedy, P. L., Bartuszevige, A. M., Houle, M., Humphrey, A. B., Dugger, K. M., & Williams, J. (2014). Stable occupancy by breeding hawks (Buteo spp.) over 25 years on a privately managed bunchgrass prairie in northeastern Oregon, USA. The Condor, 116(3), 435-445. doi:10.1650/CONDOR-12-174.1

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