Cardellina pusilla pusilla, C. p. pileolata
Status: Fairly common regular spring migrant east and west, uncommon central. Common fall migrant west, uncommon east and central. Accidental in summer.
Documentation: Specimens: pusilla, UNSM ZM10790, 4 Sep 1909 Roca, Lancaster Co; pileolata, UNSM ZM6916, 13 Sep 1919, Monroe Canyon, Sioux Co.
Taxonomy: There are three subspecies (Pyle 1997): chryseola, breeding in coastal British Columbia to southwest California, pileolata, breeding from Alaska to northern Alberta and south to eastern California and central New Mexico, and pusilla, breeding from eastern Alberta to Newfoundland and south to northern Minnesota and Nova Scotia.
The subspecies pileolata and pusilla occur in Nebraska (Rapp et al 1958, Zimmer 1913). Western pileolata is uncommon in spring and common in fall, mostly in the west. Pusilla is fairly common in spring and uncommon in fall, mostly in the east in both seasons. Zimmer (1913) noted that both occurred in Thomas Co in the central.
Spring: Apr 20,20,21 <<<>>> Jun 7,7,8
Migration is from late Apr through late May. There are earlier reports 14 Apr 1976 Adams Co, 15 Apr 1979 Garden Co, 15 Apr 2017 Red Willow Co, and 17 Apr 1974 Lancaster Co, and a later report 13 Jun 1999 Enders Reservoir, Chase Co.
This species is a statewide migrant, although few occur in the central in spring, when the western and eastern migrants are less numerous and tend to be distributed at opposite ends of the state.
- High counts: 14 in Sarpy Co 13 May 1995, 8 at Wilderness Park, Lancaster Co 11 May 2018, and 8 at Fontenelle Forest, Sarpy Co 12 May 2018.
- A good total for the season was 162 in 2018.
Summer: There is a single documented mid-summer report, a male on 8 Jul 2006 at Valentine NWR, Cherry Co (Silcock 2006).
Subspecies pileolata breeds in the central Colorado and central-west Wyoming mountains, but not in the Black Hills of South Dakota (Tallman et al 2002). There is, however, a single summer record for South Dakota, 10 July 1977 at Rapid City (Tallman et al 2002).
Fall: Aug 8,9,11 <<<>>> Oct 24,25,26
Migration is from mid-Aug through early Oct, although there are earlier reports 20 Jul 2017 Dixon Co, 29 Jul 2004 Wind Springs Ranch, Sioux Co, 3 Aug 1963 Webster Co, 4 Aug 2014 Scotts Bluff Co, and 5 Aug 2007 Washington Co. Departure from breeding grounds may begin as early as the second week in Aug (Ammon and Gilbert 2020). There are two very late reports 20 Nov 1976 Boone Co and 29 Dec 2010 Scottsbluff, Scotts Bluff Co, a male. There are a few winter records as far north as Colorado, including one on the eastern plains 20 Dec (Ammon and Gilbert 2020; eBird.org, accessed November 2017).
Migrants, as indicated by high counts below, are more numerous in the west in fall, where most birds are brightly-colored examples of pileolata; Dunn and Garrett (1997) also noted that pileolata is more common in fall on the western Great Plains than in spring.
High counts: 81 in Kimball Co 7 Sep 2001, 75+ at Oliver Reservoir, Kimball Co 12 Sep 2000, and 70 there 1 Sep 2001.
NWR: National Wildlife Refuge
UNSM: University of Nebraska State Museum
Photograph (top) of a Wilson’s Warbler at Papillion, Sarpy Co 15 May 2013 by Phil Swanson.
Ammon, E.M. and W.M. Gilbert. 2020. Wilson’s Warbler (Cardellina pusilla), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.wlswar.01.
Dunn, J.L., and K.L. Garrett. 1997. A field guide to warblers of North America. Houghton Mifflin Company, Boston, Massachusetts, USA.
Pyle, P. 1997. Identification Guide to North American Birds. Part I, Columbidae to Ploceidae. Slate Creek Press, Bolinas, California, USA.
Rapp, W.F. Jr., J.L.C. Rapp, H.E. Baumgarten, and R.A. Moser. 1958. Revised checklist of Nebraska birds. Occasional Papers 5, Nebraska Ornithologists’ Union, Crete, Nebraska, USA.
Silcock, W.R. 2006. Summer Field Report, June-July 2006. NBR 74: 78-95.
Tallman, D.A., Swanson, D.L., and J.S. Palmer. 2002. Birds of South Dakota. Midstates/Quality Quick Print, Aberdeen, South Dakota, USA.
Zimmer, J.T. 1913. Birds of the Thomas County Forest Preserve. Proceedings Nebraska Ornithologists’ Union 5: 51-104.
Silcock, W.R., and J.G. Jorgensen. 2020. Wilson’s Warbler (Cardellina pusilla), Version 1.0. In Birds of Nebraska — Online. www.BirdsofNebraska.org
Birds of Nebraska – Online