North American Birds

VOLUME 67 NO3 2014

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

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Page 9 of 179

Figure 6. Breeding after-third-year abieticola at Ottawa, Ontario 23 July 2006. Note dark throat, broad belly markings, and rufous wash to chest. This bird lacked multiple tail bands. Photograph by Wilson Hum. Figure 7. Migrant after-second-year abieticola at Vaughn, Montana 13 October 2011. Note extensive bellyband, dark streaks on sides of whitish chest, pale uppertail coverts, and multiple tail bands. Photo- graphs by Brian L. Sullivan. 376 n o r t h a m e r i c a n b i r d s n o r t h e r n r e d - ta i l e d h aw k r e v i s i t e d for instance, with Krider's Red-tailed Hawk (B. j. kriderii) (see Figure 9d in Liguori and Sulli- van 2010b and Figure 6 in Sullivan and Liguori 2010; in both cases, female abieticola are identi- fed as heavily marked borealis). An extensive review by the authors of photo- graphs and of specimens indicates that breed- ing records for typical abieticola span the bo- real forest from central Alaska to Labrador. The boreal forest shows remarkably little change in species composition from western Alaska to Atlantic Canada, and several widespread bird species that otherwise show pronounced geo- graphic variation are represented by a single subspecies in this habitat, e.g., Slate-colored Junco (Junco hyemalis hyemalis), Yellow-shafted Flicker (Colaptes auratus luteus), and Myrtle Warbler (Setophaga coronata coronata). In this context, a far larger breeding range for abieticola than described by Todd (1950) or Dickerman and Parkes (1987) would not be surprising. The extent of the wintering range of abieticola is not known. A collaborative effort over the past decade to study thousands of photographs of Red-tailed Hawks across North America (Liguo- ri, Sullivan, Lish, and many others) suggests that abieticola winters largely from the Great Plains (see Dickerman 1989) eastward through the Northeast and sparingly into the northern mid- Atlantic states; thus its winter range overlaps extensively with that of borealis. The authors are aware of no records of abieticola from the Caroli- nas through Florida, and only a few records are known from Gulf coastal states. The collabora- tive study of photographs, and the authors' ex- tensive observations of Red-tailed Hawks in the western United States (1997-2014), suggest that abieticola is very uncommon or rare from the Rocky Mountains westward in winter, with few birds documented from the region. Migration routes in abieticola are also little known. The authors' 1993-2013 seasonal stud- ies of raptor migration at sites on the Great Lakes (Derby Hill, NY; Braddock Bay, NY; Whitefsh Point, MI; Hawk Ridge, MN) and on the Atlantic coast (Cape May Point, NJ; Kipto- peke, VA), together with the recent collabora- tive photographic study, suggest a mostly cen- tral and easterly migration route for abieticola; this route fts well with a wintering range that lies mostly east of the Rockies. Among the up to 8000 Red-tailed Hawks that pass through the Pembina Valley of Manitoba in spring, for in- Figure 5. After-third-year abieticola migrants at Gunsight Mountain, Alaska, 10 April 2009. These were potentially the frst abieticola reported in Alaska, but the subspecies has been noted in small numbers there since 2009. Note promi- nent bellybands, streaked chest sides, dark throats, and rufous wash to chest (right). Photographs by Jerry Liguori. NAB 67-3 2-NorthernRed-tailed Hawk-R3.indd 376 3/19/14 9:59 AM

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