The sooty fox sparrow (Passerella (iliaca) unalaschcensis) contains the darkest-colored
taxa in the
genusPasserella. It is currently classified as a "subspecies group"[1] within the
fox sparrow pending wider-spread acceptance of species status. It has long been suspected to be a separate
evolutionary lineage due to
morphological distinctness (Swarth 1920), and this is confirmed by analysis of
mtDNAsequence and
haplotype data (Zink 1994, Zink & Kessen 1999, Zink & Weckstein 2003). This group appears to be most closely related to the
thick-billed and/or
slate-colored fox sparrows (Zink 1996, Zink & Weckstein 2003).
Description
The sooty fox sparrow complex varies
clinally in intensity of color. The upperparts and head are a variable shade of brown, with streaks on the underparts of the same color. The northernmost birds are a sandy brown, while southernmost birds are a dark coffee-like color. Sooties prefer to breed in willows and alders at the edge of wet habitats. Beadle & Rising (2003) describe their call note as a sharp zitt or thik, while Sibley (2000) says it is a loud smack like that of the
red fox sparrow.
Subspecies
Six subspecies are usually recognized in the sooty fox sparrow complex, ranging from unalaschensis in the
Aleutians to fuliginosa in extreme northwestern
Washington:
There are two distinct groups known from the winter range: brownish ash-gray birds with a longer and more pointed bill, and darker lead-gray birds with thicker, blunter bills; the taxonomic significance of this is unknown (Weckstein et al. 2002). Seems to
intergrade with sinuosa and insularis where their ranges meet. (Swarth 1920)
Breeds on the mainland south from the
Stikine River to northwestern Washington. Winter range from southwestern British Columbia south to coastal central California. (Weckstein et al. 2002)
Darker and sootier than townsendi, with the largest and most plentiful breast spots (Weckstein et al. 2002).
annectens Ridgway, 1900:
Breeds along the Pacific Coast from northern
Yakutat Bay to
Cross Sound. Winter range coastal central California.(Weckstein et al. 2002)
Intermediate between sinuosa and townsendi (Swarth, 1920). Morphology and range suggest its validity should be checked.
insularis Ridgway, 1900:
Breeding limited to
Kodiak Island. In winter, found along the Pacific Coast southwards to southernmost California.(Weckstein et al., 2002)
Brighter and more uniformly ruddy above, with strong and rich brown breast spots; under tail-coverts tinged buff (Weckstein et al. 2002).
Intermediate between unalaschcensis and insularis, but bill markedly more slender than in either (Weckstein et al. 2002).
chilcatensis Webster, 1983:
The "non-typical fuliginosa" of Swarth (1920), breeding between the
Chilkat River area to
Stewart and surroundings (British Columbia), and wintering along the coast, mainly between
Oregon and the
San Francisco Bay region (Weckstein et al., 2002).
Much like fuliginosa, but duller and shorter-tailed. Not usually accepted as distinct by recent reviewers (e.g., Zink 1994, Rising & Beadle 1996, Zink & Kessen 1999), although the presence of similarly distinct birds in unalaschcensis suggests the matter warrants more research.
Beadle, David & Rising, Jim D. (2003): Sparrows of the United States and Canada : the photographic guide. Princeton University Press, Princeton.
ISBN0-691-11747-0 p. 174
Rising, Jim D. & Beadle, David (1996): A Guide to the Identification and Natural History of the Sparrows of the United States and Canada. Academic Press, San Diego.
ISBN0-12-588971-2
Swarth H. W. (1920): Revision of the avian genus Passerella with special reference to the distribution and migration of the races in California. University of California Publications in Zoology21: 75–224.
Weckstein, J. D.; Kroodsma, D. E. & Faucett, R. C. (2002): Fox Sparrow (Passerella iliaca). In: Poole, A. & Gill, F. (eds.): The Birds of North America715.
Academy of Natural Sciences, Philadelphia, PA &
American Ornithologists' Union, Washington, D.C. Online version, retrieved 2006-11-27.
doi:
10.2173/bna.715 (requires subscription)
Zink, R. M. (1994): The Geography of Mitochondrial DNA Variation, Population Structure, hybridization, and Species Limits in the Fox Sparrow (Passerella iliaca). Evolution48(1): 96-111.
doi:
10.2307/2410006 (HTML abstract, first page image)
Zink, Robert M. & Kessen, A. E. (1999): Species Limits in the Fox Sparrow. Birding31: 508–517.
Zink, Robert M. & Weckstein, Jason D. (2003): Recent evolutionary history of the Fox Sparrows (Genus: Passerella). Auk120(2): 522–527. [Article in English with Spanish abstract]
DOI: 10.1642/0004-8038(2003)120[0522:REHOTF]2.0.CO;2
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