Status: Common regular spring and fall migrant west and west-central, rare east-central, rare casual east. Fairly common regular breeder west. Uncommon regular winter visitor west and central, rare casual east.
Documentation: UNSM ZM6695, 24 May 1900 Monroe Canyon, Sioux Co.
Taxonomy: No subspecies are recognized.
See Eastern Bluebird for discussion on hybridization with that species.
Spring: Feb 11,12,14 <<<>>> summer
Dates above are for the breeding range only. Migrants arrive on the breeding range in late Feb and are territorial soon after; a pair was at a James Ranch, Sioux Co, nest box by 10 Mar 1995, and eight pairs were at nest boxes in the Wildcat Hills of Banner and Scotts Bluff Cos by 22 Mar 2003.
Migrants occur in areas east of the breeding range, mostly in the Panhandle; Arthur and Grant Cos each hosted two on 8 Mar 2013, and one was easterly in Hall Co 14 Mar 2014. In 2015 there were several easterly reports: eight in Custer Co 24 Feb 2015, one in Frontier Co 15 Mar, 15 in Dawson Co 15 Mar, and seven on a frozen pond in Custer Co 1 Mar.
There are a few reports in May of presumed tardy migrants away from the breeding range: a pair was at Bushnell Cemetery, Kimball Co 1 May 2004, and singles were at Valentine, Cherry Co 12 May 1985, in Keith Co 15 May 2015, a “pair” in Lincoln Co 17 May 2014, at Lewellen, Garden Co 19 May 2011, and 1 Jun 2013 and 24 May 2014 at Agate Fossil Beds NM, Sioux Co.
- High counts: 100+ south of Gering, Scotts Bluff Co 22 Mar 2002, 100 there 10-12 Apr 1997, and 65 at Crescent Lake NWR, Garden Co on 16 Mar 1994.
Summer: Regular breeding occurs in open pine woodlands associated with areas of high relief in the Panhandle. Eastern limits on the Pine Ridge are in Sheridan Co, where there are reports 4 Jun 1986 and 20 Mar-12 Jun 1992. In the Wildcat Hills there are reports east to extreme southeast Banner Co on 17 Jun 2000 and 13 Jun 2009, and on the Bighorn Escarpment in southwest Morrill Co 18 Jun 2010. Mollhoff (2016) showed an increase in reports in Banner and Kimball Cos, including confirmed breeding in western Kimball Co. There were reports from Kimball Co 7 and 15 Aug 1996 and 17 Aug (year not given) that suggest breeding occurred in the 1990s.
There are occasional breeding season reports of birds out of the expected breeding range. A remarkable extralimital report was of a pair feeding young 17 May 1992 at a picnic shelter at Red Willow Reservoir, Frontier Co (Mollhoff 2001). The only other breeding season reports away from the breeding range are 28 Jun 1969 McPherson Co, 4 Jul 1988 Keith Co, and 10 Jul 2015 at Walgren Lake, Sheridan Co 10 Jul 2015.
An unusual summer aggregation of 100 in southern Scotts Bluff Co 30 Jul 2011 was ascribed to large numbers of grasshoppers in the area.
- Breeding phenology:
Nest-building: 10-22 Mar
Eggs: 10 May-10 Jul
Nestlings: 31 May-21 Jun
Fledglings: 29 Jun- 17 Jul
Fall: summer <<<>>> Nov 5,7,8
Dates above are for the breeding range only. Migrants leave the breeding range by late Oct, although there is a later report 19 Nov 1966 Scotts Bluff Co. Flocking may occur on the breeding range by early Sep; 25 were in West Ash Canyon, Dawes Co 4 Sep 2016.
Easterly fall migrants were singles in 29 Sep 2007 Thomas Co, 11 Oct 2016 Crescent Lake NWR, 23 Oct 2016 Merrick Co, three on 27 Oct 1989 NNF Bessey, Thomas Co, 29 Oct 2003 Logan Co, three on 30 Oct 2016 Franklin Co, and five on 13 Nov 2016 Gosper Co.
- High counts: 133 in southwest Kimball Co 13 Oct 1998, 31 in the western Panhandle 16 Oct 1999, and 22 in Dawes Co 8 Oct 1995.
Winter: Sep 26,28,29 <<<>>> Apr 12,15,18
Dates above are for the wintering range.
This is perhaps the only species whose summer and winter ranges are in separate Nebraska locations with no overlap, possibly performing an “altitudinal migration” between summer and winter ranges. There are, however, no banding data to show that the same birds might be involved. The summer range is completely abandoned in winter (Rosche 1982).
Wintering birds are most commonly found along the Platte River Valley, east to southwest Dawson Co, although large numbers were wintering in Merrick Co near Hordville 1978-79 (Morris 1979). The extensive juniper area in southeast Lincoln Co and adjacent parts of Dawson, Frontier and Hayes Cos appears to hold most wintering Mountain Bluebirds. This habitat appears to be somewhat unusual for this species in winter, which prefers “more open winter habitats than its congeners” (Power and Lombardo 1996) but is likely because of abundant food supply of juniper berries. The North Platte CBC has recorded an average of 133 birds each year since 1987-88, with a high of 400 in 1988-89; 400 were in cedar canyons in southeast Lincoln Co 2 Jan 2000.
Arrival in the winter range is in early Oct, although there are earlier reports: a family group of five in southeast Lincoln Co 12 Sep 2008 and 15 Sept 1963 Lincoln Co.
The last birds depart in early to mid-Apr, although there are later reports 21 Apr 1941 Logan Co, 25 Apr Garden Co, 26 April 1946 Logan Co, and 17 May 2014 Lincoln Co.
Winter reports away from the Platte River Valley are few. Five were on the Harlan County Reservoir CBC 16 Dec 2014, a first count record, and presumably the same five were at Alma SL, Harlan Co 21 Dec; a CBC high at Harlan Co Reservoir was the 18 on 14 Dec 2018. One was in Red Willow Co 10 Dec 2002. There are reports from Logan Co 1 Jan 1952, 1965, and 1967, and 19 reports for the east in the period 6 Oct-17 Apr, including a specimen, HMM 28435, a male taken in Adams Co 26 Mar 1955.
Apparently, this species does not normally winter in the Niobrara River Valley, although three were at Niobrara SP, Knox Co 5 Jan 2002, and 4-5 were found along the Niobrara River Valley in Boyd Co 18 Feb 2016. It was listed as a “possible winter resident” at NNF Bessey (Bray 1994); the only specific reports are of two there 16 Mar 1997 and one there 3 Mar 2009. During winter 2015-2016 there were reports as far east as Dixon Co, where one was on the Ponca SP CBC 14 Dec and there was a “large flock” at NNF Bessey 30 Jan 2016.
CBC: Christmas Bird Count
HMM: Hastings Municipal Museum
NNF: Nebraska National Forest
NM: National Monument
SL: Sewage Lagoons
SP: State Park
UNSM: University of Nebraska State Museum
Bray, T.E. 1994. Habitat utilization by birds in a man-made forest in the Nebraska Sandhills. Master’s thesis, University of Nebraska-Omaha, Omaha, Nebraska, USA.
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, L. 1979. Mountain Bluebirds (and others) near Hordsville. NBR 47: 18.
Power, H.W., and M.P. Lombardo. 1996. Mountain Bluebird (Sialia currucoides), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.222
Rosche, R.C. 1982. Birds of northwestern Nebraska and southwestern South Dakota, an annotated checklist. Cottonwood Press, Crawford, Nebraska, USA.
Silcock, W.R., and J.G. Jorgensen. 2018. Mountain Bluebird (Sialia currucoides), Version 1.0. In Birds of Nebraska — Online. www.BirdsofNebraska.org