EASTERN BLUEBIRD

Sialia sialis

Status:  Common regular spring and fall migrant and breeder east and central, uncommon west. Uncommon regular winter visitor south and east, rare north, rare casual west.

Documentation:  Specimen: UNSM ZM6688, 23 Mar 1891 Lincoln, Lancaster Co.

Taxonomy:  There are eight subspecies generally recognized (Pyle 1997), three of these north of Mexico:  fulva of the southwest USA to central Mexico, grata of South Florida (included in sialis by Gowaty and Plissner 2015), and sialis, of southern and southeastern Canada, eastern and central USA and northeastern Mexico. Nebraska birds are presumed sialis.

Occasional hybridization with Mountain Bluebird has been recorded, including a Nebraska example discussed below (see Summer). A male Mountain Bluebird, far east of its normal range, mated with a female Eastern Bluebird in Riley Co, Kansas, in 1997 and fledged several young (Cavitt et al 1998). Hybridization between these species occurred in less than one percent of over 8000 pairs of the two species in southwestern Manitoba (Rounds and Munro 1982).

Spring:  Mar 16,17,18 <<<>>> summer (west)

Due to a decline in numbers as winter progresses, a spring influx is detectable in mid-Mar in the west; there are no Feb reports there, but these early Mar reports: 3 Mar 2018 Lake McConaughy, Keith Co, 7 Mar 2015 singing male Wildcat Hills SRA, Scotts Bluff and Banner Cos, 8 Mar 1970 Scotts Bluff Co, 11 Mar 1995 Sioux Co, and 12 Mar 2016 Wildcat Hills NC, Scotts Bluff Co. In recent years spring migrants have become more numerous in the Panhandle.

Migrants become apparent in the east in late Feb as overall numbers increase, peaking in mid- to late Mar; because of wintering birds, early arrival dates are hard to discern.

  • High counts:  200 in Gage Co 11 Mar 2006, “hundreds” in southeast Lincoln Co 29 Mar 2006.

Summer:  The historical range of oak savannah once defined the breeding range of Eastern Bluebird, which was generally limited to the southeastern third of Nebraska. Currently, however, this species breeds statewide, utilizing open areas where deciduous trees are present (Rosche 1982). Numbers are lowest in the western Sandhills and the southern Panhandle, and generally decline from east to west. The provision of nest boxes for bluebirds in the Panhandle and elsewhere has attracted Eastern Bluebirds in recent years.  BBS trend analysis show Eastern Bluebirds have increased at an annual rate of 3.80 (95% C.I.; 1.95, 5.60) statewide during the period 1966-2015 (Sauer et al 2017).

The only reports from the western Sandhills are of two on 8 Jun 2010 at Crescent Lake NWR, Garden Co, two on 6 Jun 2015 between Smith Lake WMA, Sheridan Co and Lakeside, Grant Co, two reports from Smith Lake WMA, a single bird on 5 Jul 2011 and two on 14 Jun 2016, and one along Highway 92 in Arthur Co 7 Jul 2017.

Expansion into the Pine Ridge is recent, but reports have increased markedly since 2000, and the species is now widespread as a breeder on the Pine Ridge (Mollhoff 2016). Although there are three old specimens for the Panhandle, all from Monroe and Warbonnet Canyons in northwest Sioux Co, 24 May 1900 (UNSM ZM6692 and ZM6693) and an immature 21 Jun 1901 (UNSM ZM6694), and Ducey (1988) cited a nest record card for Dawes Co in 1962, the first modern Pine Ridge record was as recent as 1974 in Sioux Co (Ducey 1988). Rosche (1982), however, had stated that there were no definite nesting records for the Pine Ridge at that time, and included only one summer report from the northwest, a pair at a hole in “cottonwood forest” at Box Butte Reservoir, Dawes Co in summer 1981. More recently, Wilson et al (1985, 1986, Williams 1985) found an apparent hybrid male Eastern X Mountain Bluebird mated with a female Mountain Bluebird in Dawes Co, some eight miles south of Crawford, in the summer of 1985. This pair fledged two broods from a nest box.  Wilson et al (1986) suggested that hybridization in this case may have resulted from low numbers of summering Eastern Bluebirds in the area and the resulting shortage of mates. A nest with young was found in West Ash Canyon, Dawes Co, 2 Jun 2000 (Mollhoff 2001), and a male was feeding three recent fledglings in Smiley Canyon, Dawes Co, 1 Aug 2001.  A few miles south of the Pine Ridge, four young were fledged at Box Butte Reservoir, Dawes Co 8 Jul 1994 (Silcock and Rosche 1994).

The first nesting record in Scotts Bluff Co was in 1986, when a pair was present 24 May-2 Aug and used a box set out for Mountain Bluebirds (Cortelyou 1986). Most Eastern Bluebird sightings in Scotts Bluff Co are at the Wildcat Hills NC, where six pairs and at least one nestling were at the nest boxes there 13-14 Jun 1998, and seven nests were in nest boxes there 16 Jun 2002. Mollhoff (2016) did not show a notable increase in the number of reports from the Scotts Bluff Co area, in contrast to the recent increases on the Pine Ridge.

The only records of breeding from the southern Panhandle are the fledging of four young in Cheyenne Co 4 Jul 2003, a nest with eggs in the Limber Pine BBA block, Kimball Co 25 Jul 2006 (Mollhoff 2016, unpublished data), confirmed breeding in Deuel County in 2007 (Mollhoff 2016), and an adult and juvenile at Oliver Reservoir, Kimball Co 19 Aug 2011.

  • Breeding phenology:
    Nest building: 7 Mar-23 May
    Eggs: 3 Apr-14 Jul
    Nestlings: 30 Apr-30 Jul
    Fledglings: 6 Jun- 30 Jul

   In Otoe Co, 80 had fledged from boxes by 31 Jul 2005, and 90 by 31 Jul 2012. A productive nest-box near Bennington, Douglas Co             produced three broods, each of three young, during summer 2010.

Fall: Peak migration is in Oct; in the north and west most birds depart by late Oct, although there are later reports 2 Nov 2010 Scotts Bluff Co and 7 Nov 2015 Fort Niobrara NWR, Cherry Co. Departure in the south and east is difficult to detect as many birds linger into winter.

Fall flocking may occur early; a flock of 19 was in Johnson Co 13 Jun 2012. Juvenile flocks may migrate independently of adults, remaining cohesive throughout winter and heading north as a flock the following spring (Gowaty and Plissner 2015).

  • High counts: 300 in Lancaster Co 2 Nov 2010, 200-300 in Lincoln Co 20 Oct 2004, 200 between Center and Niobrara in Knox co 3 Oct 1998, and “hundreds” in Lancaster Co 17 Sep 2011.

Winter: CBC data show that by late Dec Eastern Bluebirds are still distributed statewide, but highest numbers are in the extreme southeast. Observations from eBird (eBird.org, accessed October 2017) show that during Jan few remain in the north and west, but by Feb northward movement is beginning, most noticeably in the south-central and east.

Although there are several midwinter reports from the north, there are only three midwinter reports from the Panhandle, 1-7 Jan 2013 and 20 Jan 1979 Scotts Bluff Co, and 19 Feb 2000 Ash Hollow SHP, Garden Co.

High CBC counts include 234 at Branched Oak Lake-Seward, Lancaster and Seward Cos 20 Dec 2015, 209 there 16 Dec 2012, 176 at DeSoto NWR, Washington Co 27 Dec 2008 and 175 at Lincoln, Lancaster Co 18 Dec 2010.

Abbreviations

BBA: Breeding Bird Atlas
BBS: Breeding Bird Survey
CBC: Christmas Bird Count
NC: Nature Center
NWR: National Wildlife Refuge
SHP: State Historical Park
SP: State Park
SRA: State Recreation Area
UNSM: University of Nebraska State Museum
WMA: Wildlife Management Area (State)

Acknowledgement

Photograph (top) of a Eastern Bluebird at Schramm State Park, Sarpy Co 7 May 2006 by Phil Swanson.

Literature Cited

Cavitt, J.F., A.T. Pearse, and D.A. Rintoul. 1998. Hybridization of Mountain Bluebird and Eastern Bluebird In Northeastern Kansas. Kansas Ornithological Society Bulletin 49: 21-25.

Cortelyou, R.G. 1986. 1986 (Sixty-first) Spring Occurrence Report. NBR 54: 46-64.

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

Gowaty, P.A., and J.H. Plissner. 2015. Eastern Bluebird (Sialia sialis), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.381

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.

Mollhoff, W.J. 2001. 1999-2000 Nebraska nesting report. NBR 69: 92-101.

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

Rounds, R.C., and H.L. Munro. 1982. A review of hybridization between Sialia sialis and S. currucoides.  Wilson Bulletin 94: 219-223.

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.

Silcock, W.R., and R.C. Rosche. 1994. Summer Field Report, June-July 1994, NBR 62: 102-116.

Williams, F. 1985. Southern Great Plains Region. American Birds 39: 931-933.

Wilson, B.L., J. Minyard, H. Minyard, and T.E. Bray. 1985. Hybrid bluebirds in the Pine Ridge. NBR 53: 67.

Wilson, B.L., J. Minyard, and H. Minyard. 1986. Hybrid bluebird update. NBR 54: 26-27.

Recommended Citation

Silcock, W.R., and J.G. Jorgensen.  2018.  Eastern Bluebird (Sialia sialis), Version 1.0. In Birds of Nebraska — Online. www.BirdsofNebraska.org


Birds of Nebraska – Online