Fall migration of radio-tagged Broad-winged Hawks en California

Little is known about migration patterns of Broad-winged Hawks (Buteo platypterus) in the western United States apart from small numbers that have been recorded at migration monitoring sites. To better understand their movements in coastal California, we radio-tracked 5 juveniles (1 in 1994, and 4 f...

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Bibliographic Details
Published in:The Wilson journal of ornithology 2020-03, Vol.132 (1), p.15
Main Authors: Capitolo, Phillip J, Jesus, Lynn J, Harper, Alan B, Fish, Allen M, Hull, Angus C
Format: Article
Language:English
Subjects:
Hawks
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Summary:Little is known about migration patterns of Broad-winged Hawks (Buteo platypterus) in the western United States apart from small numbers that have been recorded at migration monitoring sites. To better understand their movements in coastal California, we radio-tracked 5 juveniles (1 in 1994, and 4 from 2012 to 2015) during fall migration from the Marin Headlands (near San Francisco) to the US--Mexico border. One hawk died near the Headlands within 2-3 d of release and the other 4 crossed into Baja California in 4-6 flight days with no stopovers beyond the Headlands. Daily straight-line flight distances ranged from about 110 to 265 km (mean = 189 [+ or -] 47 km SD). Migration began 2.5-3 h after sunrise and ended a similar amount of time before sunset. Flight paths along mountain ranges, and radio signal patterns, indicated slope-soaring was a primary strategy. The detailed flight paths we identified will be helpful to better evaluate proposed renewable energy facilities, given their current rapid development and potential for killing birds. More study is needed to determine complete migration routes and breeding and wintering grounds of Broad-winged Hawks on the Pacific coast. Received 26 June 2019. Accepted 18 February 2020.
ISSN:1559-4491
1938-5447