BREWER’S BLACKBIRD

Euphagus cyanocephalus

Status:  Common regular spring and fall migrant west and central, uncommon east. Fairly common regular breeder west. Rare regular winter visitor from the North Platte and Platte River valleys south and Missouri River Valley.

Documentation:  Specimen: UNSM ZM7025, 20 Jun 1901 Indian Creek, Sioux Co.

Taxonomy:  No subspecies are recognized (Jaramillo and Burke 1999, Gill and Donsker 2017), although Pyle (1997) recognized three weakly-differentiated subspecies, minusculus of coastal Oregon and California, brewsteri, breeding from northwest Territories to northern Oregon and Wisconsin, wintering from California to Georgia, and cyanocephalus, breeding from Oregon to California east to southern Wyoming and northern New Mexico, wintering to California and south Texas.

If these subspecies are recognized, cyanocephalus is the Nebraska breeding subspecies, and both it and brewsteri migrate through the state.

Changes since 2000: Brewer’s Blackbird has expanded its breeding range southward in the Panhandle since 2007; for many years it bred only on or near the Pine Ridge. This expansion is probably related to expansion of the breeding populations in southeast Wyoming and northeast Colorado which adjoin the Nebraska border.

Spring:  Mar 4, 5, 6 <<<>>> May 31, 31, 31 (central, east), Mar 31, Apr 1, 2 <<<>>> summer (west)

Earlier dates central and east of probable early migrants are 12 Feb 2015 two in a blackbird flock at Branched Oak Lake, Lancaster Co, and 23 Feb 1985 Boone Co. Other Feb dates are discussed in Winter, below.

Earlier dates west are 8 Mar 2015 Dundy Co, 22 Mar 2013 Sheridan Co, and 28 Mar (Rosche 1994). For earlier dates west, see Winter.

Later dates central and east are 6 Jun 1973 Lancaster Co, 7 Jun 1992 Phelps Co, 9 Jun 2017 Valentine NWR, Cherry Co, 11 Jun 2015 Lincoln Co, 11 Jun 2015 Keith Co, 13 Jun 2002 Nenzel, Cherry Co, 13 Jun 2020 Valentine NWR, Cherry Co, 14 Jun 1986 Thurston Co, 14 Jun 1997 Keith Co, and 15 Jun 2017 Dawson Co.

As with other Nebraska “blackbird” species, migration begins around early Mar, and peak migration probably occurs in mid- to late Apr (Rosche 1994). Away from the breeding range, migration ends by late May, when most birds are at breeding sites.

It has been noted this species does not usually occur in mixed flocks with other blackbird species (Rosche 1994, Jorgensen 2012).  In the east, it also appears attracted to recent grassland burns (Jorgensen 2012, see High Counts, below). Peak counts in the east and west are on almost identical dates.

Migrants arrive later in the Panhandle, in early Apr, although there are earlier reports  and 15 Mar 1965 Dawes Co, but peak counts in the east and west are on almost identical dates. High counts in the east are on burned grassland.

  • High counts:  
    • East:  1000, including 800 in one flock at a burned pasture, in the eastern Rainwater Basin 14 Apr 2001, 300 in Fillmore Co 27 Apr 2000 (Jorgensen 2012), and 300 on a burn at Ponca SP, Dixon Co 25 Apr 2014.
    • West:  “several hundred” in Scotts Bluff Co 27 Apr 1994, a mixed-gender flock of 200 near McCook, Red Willow Co 25 Apr 2009, and 186 in Banner 2 May 2020.

Summer: Traditionally, Brewer’s Blackbird bred mostly in Sioux Co, particularly on the grasslands in the Harrison area (Rosche 1982). A colony had been present about 10 miles east of Harrison for many years but had not been occupied for some 15 years until five pairs were present 11 May 2016; there were two nests with eggs 23 May (Wayne Mollhoff, personal communication). Mollhoff (2001, 2016) showed that breeding occurred throughout the Pine Ridge to Sheridan Co during both breeding bird atlas periods (1984-1989 and 2006-2011), but only in the second atlas period was breeding noted south of the North Platte River. There were breeding season reports 2006-2011 in Scotts Bluff, Banner, Kimball, and Morrill Cos; breeding was confirmed in Scotts Bluff and Morrill Cos. This expansion of range was not unexpected, as Brewer’s Blackbirds breed in northeast Colorado (CBAP 2016) and Wyoming (Faulkner 2010) just west of the Nebraska Panhandle and the southwest and tend to move breeding colonies periodically. Probably reflecting this range expansion in southwest Nebraska, BBS trend analysis show the species has increased 5.23% (95% C.I.; -2.34, 13.89) during 1966-2015 (Sauer et al 2017).

There are breeding season reports in Scotts Bluff Co 30 Jun 1965, 30 Jun 1982, and 23 Jul 1983, but breeding activity was not noted until 2007-2008, when at least one pair established in unusual habitat on the north side of Scotts Bluff NM. The first confirmed breeding for the county was 22 Jun 2010, when the first record on the Murray Lake BBS route was provided by birds at five stops, including two instances of adults carrying food. At about the same time, an adult was carrying food at Wildcat Hills NC, Scotts Bluff Co 19 Jun 2010. Reports apparently began in Morrill Co in 1987, when young were seen by Rosche (Ducey 1988); a female was feeding an immature on the Bighorn Escarpment south of Redington, Morrill Co 25 Jun 1995, and this location has hosted at least one breeding colony since. In 1998, 15+ pairs were present, and an active nest and three females carrying nest material were noted 15-16 May 1998 (Wayne Mollhoff, pers. comm.). Breeding was confirmed in Banner Co during 2006-2011 and there were breeding season reports there during the same period (Mollhoff 2016). Elsewhere in the southwest adjacent to the northeast Colorado plains breeding range are reports of six on a BBS route near Benkelman, Dundy Co 27 Jun 2007, near Bushnell, Kimball Co 6 Jul 1995 and 18 Jun 2011, up to 15 during 2-15 Jul 2018 in Cheyenne Co, and one in Red Willow Co 22 Jul 2008.

There are several reports in the western Sandhills in Sheridan, Box Butte, and Garden Cos, including a report of adults feeding young at Smith Lake WMA, Sheridan Co  (no date given; Steven Jones, pers. comm.). Additional reports from Smith Lake WMA were of two on 10-23 May 2003 and seven on 30 May 2006, and one on 20 Jul 1982. In northern Sheridan Co, it was was reported 4 Jun 1986 and 5-12 Jun 1992, two were near Gordon 5 Jun 2013, one near Rushville 1 Jul 2017 and one near the Niobrara River 21 Jul 1982. Five were seen 13 Jun 2016 in southwest Sheridan Co, one in Box Butte Co 1 Jul 2017 and four in Box Butte Co 3 Jul 2018. Further south, one was near Lakeside, Sheridan Co 13 Jun 2016, seven were in Garden Co 27 Jun 2018, and there are reports for Crescent Lake NWR, Garden Co 4 Jun 2000, 17 Jun 2006, 18 Jun 2001, and 29 Jun 1984.

There are no documented records of breeding elsewhere in Nebraska since the 1930s (see Comments). Reported occurrences of nesting in Hall, Johnson, and Lancaster Cos (Bennett 1969, 1972, 1973, 1975) are almost certainly misidentifications of Common Grackle; the Johnson Co report was of nesting in a conifer in a suburban yard, typical of that species. The 1974 Hall Co report (Bennett 1975) was based on birds seen “carrying food”; Johnsgard (1979) suggested that this report may have been of a Rusty Blackbird, although there is no evidence to suggest any species other than Common Grackle.

There are about 65 undocumented Jun and Jul reports of Brewer’s Blackbird away from the Panhandle breeding range outlined above; most, including BBS data, are from the east and south and are highly questionable.

  • Breeding phenology:
    Eggs: 1 May-14 Jun
    Nest Building: 12 (Grzybowski 1993)-16 May
    Nestlings: 31 May-22 Jun
    Fledglings 13 Jun-14 Jul

Fall:  summer <<<>>> Oct 18, 19, 20 (west); Sep 13, 14, 16 <<<>>> Nov 24, 24, 25 (central and east)

Later dates in the west are 23 Oct 2017 Box Butte Co, 26 Oct 2020 Dawes Co, 3 Nov 2019 Dawes Co, 13 Nov 2012 Garden Co, and 17 Nov 2006 Scotts Bluff Co. For later dates, see Winter.

Earlier dates central and east are 4 Sep 1983 Keith Co, and 5 Sep 2015 Otoe Co.

Later dates central and east are 29 Nov 2010 Dodge Co, and 30 Nov 2017 Otoe Co.  For later dates, see Winter.

Reports in Jul-early Aug may be late migrants or merely “summer wanderers”, as suggested by Thompson and Ely (1992) for western Kansas. Such reports are 19 Jul 1982 Valentine NWR, 28 Jul 1979 Lake Ogallala, Keith Co (Brown and Brown 2001), 14 Aug 1994 at Axtell, Phelps Co, and 17 Aug 2012 in Sherman Co.

Early flocks were the 200 in Scotts Bluff Co 8 Jul 2012 and a mixed-age flock of 45 present for “a few days” near Fort Robinson, Dawes Co 23 Jul 2018. This species may have been affected by the very dry conditions in the west in 2012 when flocks were noted on early dates: “lots were under a pivot” in Morrill Co 30 Jun and 200 were in a mixed icterid flock in Scotts Bluff Co 8 Jul.

Migrants appear statewide in late Sep; peak movement probably occurs in early Oct, and most migrants leave the state by the end of Nov. Migrants are not uncommon in the east during Oct; 200 were in Sarpy Co 15 Oct 2009, and in the same year there were eight other reports 12-31 Oct of up to 15 birds.

  • High counts:  2000-3000 near McCook, Red Willow Co 18 Oct 2004, 2000 on 2 Oct 1976 at Oshkosh, Garden Co (Rosche 1994), and 1000 near Mitchell, Scotts Bluff Co 3 Sep 2000.

Winter: Overwintering is rare and usually of fewer than five birds; larger groups tend to be transitory and rarely linger past early Jan, even in the south and east. Reports of later groups >5 are of 23 wintering below Keystone Dam, Keith Co through at least 3 Feb 2001, up to 22 during 2 Jan 1927 and 21 Jan 1930 Lincoln Co (Tout 1947), 30 at Garden County Refuge, Garden Co 5 Jan 2019 and 120 there on 2 Feb 2019, 14 in a mixed-species blackbird flock 14 Jan 2002 in Boone Co, and a group of 30 in Lancaster Co 12 Jan 2013.

There are about 35 additional records Nov-Feb from the Platte and North Platte river valleys southward and the Missouri River Valley, with these few exceptions:  2 Jan 2005 Beaver Valley CBC, 10 Jan 1981 Boone Co, 11 Jan 1986 Boone Co, and 27 Feb 2016 Pierce Co.

Highest CBC counts are 283 at Lincoln, Lancaster Co in 1986, 206 at DeSoto NWR, Washington Co in 1989, and 180 at Hastings, Adams Co in 1976.

Blake and Ducey (1991) stated that “a few overwinter some years” in southeast Holt Co.

Some undocumented winter reports are likely to have been misidentified Rusty Blackbirds.

Comments:  The recent expansion of the breeding range in the southern Panhandle is not an unprecedented phenomenon; Brewer’s Blackbird expanded its range significantly eastward “from Minnesota” beginning around 1914 (Martin 2020), particularly in Minnesota and Wisconsin (Bent 1968), implying that breeding in Nebraska during that time was likely if birds had reached Minnesota by 1914. Indeed, Glandon and Glandon (1934) considered Brewer’s Blackbird a “very common summer resident” in Logan Co, and Trostler reported a nesting colony 2.5 miles east of Niobrara at a farmstead in Knox Co 19 Jul 1904 (undated handwritten note from Trostler to Bruner in NOU Archives, fide Wayne Mollhoff). Jorgensen (2012) considered the only acceptable breeding record for the eastern Rainwater Basin one from Tout (1902), who collected eggs 9 Jun 1896 near York that were identified as those of Brewer’s Blackbird. These reports suggest that Brewer’s Blackbird may have bred across much of Nebraska in the late 1800s and early 1900s.

Abbreviations

BBS: Breeding Bird Survey
CBAP: Colorado Bird Atlas Partnership
CBC: Christmas Bird Count
NC: Nature Center
NM: National Monument
NOU: Nebraska Ornithologists’ Union
NWR: National Wildlife Refuge
SP: State Park
UNSM: University of Nebraska State Museum

Acknowledgement

Photograph (top) of a Brewer’s Blackbird in Sowbelly Canyon, Sioux Co 16 May 2017 by Michael Willison.

Literature Cited

Bennett, E.V. 1969. 1968 Nebraska nesting survey. NBR 37: 39-46.

Bennett, E.V. 1972. 1971 Nebraska nesting survey. NBR 40: 9-15.

Bennett, E.V. 1973. 1972 Nebraska nesting survey. NBR 41: 3-9.

Bennett, E.V. 1975. 1974 Nebraska nesting survey. NBR 43: 13-19.

Bent, A.C. 1968. Life histories of North American Cardinals, Grosbeaks, Buntings, Towhees, Finches, Sparrows, and allies. Bulletin of the United States National Museum 237. Three Parts. Dover Publications Reprint 1968, New York, New York, USA.

Blake, L., and J. E. Ducey. 1991. Birds of the eastern Sandhills in Holt County, Nebraska. NBR 59: 103-132.

Brown, C.R., and M.B. Brown. 2001. Birds of the Cedar Point Biological Station. Occasional Papers of the Cedar Point Biological Station, No. 1.

Colorado Bird Atlas Partnership [CBAP]. 2016. The Second Colorado Breeding Bird Atlas online database. Colorado Bird Atlas Partnership, Denver, Colorado, USA.

Cortelyou, R.G. 1993. The Spring 1993 Occurrence Report. NBR 61: 94-136.

Ducey, J.E. 1988. Nebraska birds, breeding status and distribution. Simmons-Boardman Books, Omaha, Nebraska, USA.

Faulkner, D.W. 2010. Birds of Wyoming. Roberts and Company, Greenwood Village, Colorado, USA.

Gill, F., and D. Donsker (Eds). 2017. IOC World Bird List (v 7.3), accessed 30 January 2018.

Glandon, E.W., and R. Glandon. 1934. Notes on some Logan County birds. NBR 2: 31-36.

Grzybowski, J.A. 1993. Southern Great Plains Region. American Birds 47: 426-429.

Jaramillo, A., and P. Burke. 1999. New World Blackbirds- The Icterids.  Princeton University Press, Princeton, New Jersey, USA.

Johnsgard, P.A. 1979. Birds of the Great Plains: breeding species and their distribution.  University of Nebraska Press, Lincoln, Nebraska, USA.

Jorgensen, J.G. 2012.  Birds of the Rainwater Basin, Nebraska.  Nebraska Game and Parks Commission, Lincoln, Nebraska, USA.

Martin, S.G. 2020. Brewer’s Blackbird (Euphagus cyanocephalus), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.brebla.01.

Mollhoff, W.J. 2001. The Nebraska Breeding Bird Atlas 1984-1989. Nebraska Ornithologists’ Union Occasional Papers No. 7. Nebraska Game and Parks Commission, Lincoln, Nebraska, USA.

Mollhoff, W.J. 2016. The Second Nebraska Breeding Bird Atlas. Bull. Univ. Nebraska State Museum Vol 29. University of Nebraska State Museum, Lincoln, Nebraska, USA.

Morris, R. 1994. Fall 1993 Occurrence Report (July 1-December 31). NBR 62: 3-50.

Pyle, P. 1997. Identification Guide to North American Birds. Part I, Columbidae to Ploceidae. Slate Creek Press, Bolinas, California, USA.

Rosche, R.C. 1982. Birds of northwestern Nebraska and southwestern South Dakota, an annotated checklist. Cottonwood Press, Crawford, Nebraska, USA.

Rosche, R.C. 1994. Birds of the Lake McConaughy area and the North Platte River valley, Nebraska.  Published by the author, Chadron, Nebraska, USA.

Sauer, J.R., D.K. Niven, J.E. Hines, D.J. Ziolkowski, Jr, K.L. Pardieck, J.E. Fallon, and W.A. Link. 2017.  The North American Breeding Bird Survey, Results and Analysis 1966 – 2015 (Nebraska).  Version 2.07. USGS Patuxent Wildlife Research Center, Laurel, Maryland, USA.

Thompson, M.C., and C.A. Ely. 1992. Birds in Kansas. Vol. 2. University of Kansas Museum Natural History Publications Educational Series No. 12, Lawrence, Kansas, USA.

Tout, W. 1902. Ten years without a gun. Proceedings of Nebraska Ornithologists’ Union 3: 42-45.

Tout, W. 1947. Lincoln County birds. Published by the author, North Platte, Nebraska, USA.

Recommended Citation

Silcock, W.R., and J.G. Jorgensen.  2021.  Brewer’s Blackbird (Euphagus cyanocephalus). In Birds of Nebraska — Online. www.BirdsofNebraska.org


Birds of Nebraska – Online

Updated 24 Mar 2021