Polioptila caerulea caerulea, P. c. obscura
Status: Fairly common regular spring and fall migrant east and west, uncommon central. Fairly common regular breeder east, south, and west, uncommon north.
Documentation: Specimen: UNSM 11734, 1 May 1888 Peru, Nemaha Co.
Taxonomy: Pyle (1997) recognized seven subspecies, three breeding north of Mexico: obscura, of California to Wyoming and south to Texas, deppei, of extreme south Texas, and caerulea, from Kansas to central Texas and east to the Atlantic Coast.
Until the 1990s, the only subspecies occurring in the state was eastern caerulea (Rapp et al 1958), but since then western obscura has spread into western Nebraska from the Rocky Mountains. Faulkner (2010) stated that the species (subspecies obscura) had expanded markedly in Wyoming since the mid-20th century.
In Nebraska, eastern caerulea occupies deciduous and mixed forest in the east and eastern Niobrara River Valley, and western obscura occupies Panhandle pinewoods and similar habitat in the west-central Niobrara River Valley (see Summer).
Changes since 2000: In the late 1990s a rapid increase in numbers in the Panhandle began, and since then this species has expanded dramatically to occupy most pine woodland habitat in western Nebraska, including much of the Niobrara River Valley but not the Sandhills.
Spring: Apr 4, 6, 6 <<<>>> summer, Apr 20, 22, 23 <<<>>> summer (west)
Arrival is mid- to late Apr.
Until recently this species was rarely encountered away from the east, with these few reports: a specimen UNSM ZM6707 22 Apr 1937 Lincoln Co (Tout 1947), 28 April 1953 Thomas Co, 4 May 1996 Howard Co, and 12 May 1957 Logan Co.
Following the discovery of breeding in Kimball Co in the late 1990s (see Summer), numbers of spring migrants in the west have increased rapidly. In 1998, 13-15 were found each spring until by 2001 it was becoming “widespread and almost common in the Panhandle” (Stephen J. Dinsmore, personal communication).
As a migrant, it is least numerous in central Nebraska, as might be expected with stable numbers in the east and increasing numbers in the Panhandle, although numbers in the central in spring have also increased dramatically since 2000. It was still a “rare spring transient” 22 Apr-3 Jun in the Keith Co area (Brown and Brown 2001) at about the same time numbers were increasing rapidly in the Panhandle. Similarly, it was listed as a “Casual spring and fall migrant”, but increasing, in the Rainwater Basin, where Jorgensen (2012) listed 17 total spring reports 9 Apr-25 May. Among the first spring records in central Nebraska were singles in Hitchcock Co 5 May 2003, Buffalo Co 10 Apr 2005, and in Garfield Co 15 May 2005.
- High counts: in the east, 45 at Indian Cave SP, Nemaha and Richardson Cos 26 Apr 2014, 45 at Fontenelle Forest, Sarpy Co 22 Apr 2016, and 22 at Towl Park, Omaha, Douglas Co 12 May 2016, and in the west 30 on Old Stage Rd, Scotts Bluff Co 24 May 2007, 9 there 28 May 2016, and 8 in Scotts Bluff Co 2 May 2001.
Summer: Prior to the late 1990s, this species was confined to the east; Bruner et al (1904), Rapp et al (1958), and Mollhoff (2001a) showed an essentially unchanged distribution for some 100 years primarily in the southeast, although Mollhoff (2001a) stated that it was reported “at scattered sites along the Missouri River as far as its confluence with the Niobrara River”. During 2006-2011, however, breeding reports increased in the Missouri River Valley north and west to Dakota and Knox Cos (Mollhoff 2016). The only reports north and east of the Elkhorn River Valley in 1984-1989 were one each for Dakota and Knox Cos (Mollhoff 2001a), but during 2009-2014 there were 13, presumably eastern birds expanding and consolidating their range. One of 2-4 birds at Ashford Scout Camp, Thurston Co, was carrying food 11 Jun 2006, the first breeding record in the extreme northeast. Reports increased in Seward, Saline, and Jefferson Cos also (Mollhoff 2016), although it is absent in summer in the Rainwater Basin, where habitat is unavailable or very limited (Jorgensen 2012).
Blue-gray Gnatcatcher has been expanding its range northward along Colorado’s eastern foothills for some time, apparently part of a general shift northward there during the last three decades (Hitch and LeBurg 2007, Kershner and Ellison 2012). The first records of this western population reaching Nebraska were on 19 Jun 1993, when a single territorial bird was found in limber pines in western Kimball Co (incorrectly cited 16 Jun in Grzybowski 1993), and another was there 24 Jun 1995. A family group was seen in the same area, including adults feeding dependent young, 22 Aug 1999, and four nests with eggs were located there 10-11 Jun 2000 (Mollhoff 2001b). Expansion of the western range northeastward is discussed below.
In the Wildcat Hills, Scotts Bluff and Banner Cos, one was on Stage Hill Road 6 Sep 1997 and several birds were located in spring 1998 in suitable breeding habitat. Numbers increased rapidly, with 21 counted 30 Jul 2000, and, in 2015, the “highest number ever banded in a season at Wildcat Hills NC” was the 21 during 24 Aug-23 Sep. On the Bighorn Escarpment, one was found 12 Sep 1997 and again in spring 1998 in Long Canyon and a single bird was reported south of Redington, Morrill Co 30 Aug 1997; three nests, two with eggs, were found there 11 Jun 2000 (Mollhoff 2001b) and 25-30 birds, including what appeared to be a few juveniles, were present 11-12 Aug 2001.
In the northern Panhandle, first records were of a single bird in Box Butte Co 2 Jun 1996 (Grzybowski 1996), two at the north end of Sowbelly Canyon, Sioux Co 6 Jul 2002, and another in Sioux Co 30 Aug 2003. Eastward on the Pine Ridge were two at Chadron SP, Dawes Co 11 Jun 2015. Elsewhere in the Panhandle, two were at Ash Hollow SHP, Garden Co 21 Sep 2003 and another two 5 Jun 2005; singles were near Crescent Lake NWR, Garden Co 7 Sep 1998 and 12 May 1999, and 1-2 were there 24 Jun 2005. Two were at Smith Lake, Sheridan Co 1 Jul 2017.
In the Niobrara River Valley, Mollhoff (2001a) had stated that it was reported “at scattered sites along the Missouri River as far as its confluence with the Niobrara River”, and Ducey (1989) suggested that this species was “extending its range into the lower Niobrara Valley” and would be “expected to breed there”. However, the only indication of westward spread in the Niobrara River Valley beyond Knox Co prior to 2007-2009 is a single record from Holt Co 4 Sep 2006; except for this record there was a gap in reports between Knox Co and northeast Cherry Co until 2015. It is more likely, based on first report dates, that gnatcatchers reached northeastern Cherry Co from the southwest via Crescent Lake NWR and NNF Bessey in Thomas Co. The first Crescent Lake NWR report was in 1999, and there were numerous reports there beginning in 2008 and at NNF Bessey beginning 21 May 2009. One was at Hyannis, Grant Co 17 May 2009. The first reports in northeast Cherry Co were of one there 25 Aug 2007, two at Fort Falls 18 Aug 2008, and one at Fort Niobrara NWR 22 Sep 2009. The gap in reports mentioned above in the Niobrara River Valley east of Cherry Co was closing by 2015, however, when there were several sightings of up to four between the Niobrara Valley Preserve and Fort Niobrara NWR 14-29 Jun 2015.
In the Platte River Valley, prior to the arrival of western birds in the late 1990s, there had been a few scattered westerly reports of presumed eastern birds. From Lincoln Co there is a specimen UNSM ZM6707 taken 22 Apr 1937 (Tout 1947) and an 11 Jun 1985 report. A female in breeding condition was netted at Cedar Point Biological Station, Keith Co, 3 Jun 1993 (Rosche 1994). A nest found there in 2010 was claimed as “the first nest of Blue-gray Gnatcatcher (Polioptila caerulea) in western Nebraska” (Barcelo and Faaborg 2012), although it was preceded by those described above in Kimball Co. The 2010 Keith Co nest was parasitized by a Brown-headed Cowbird and the pair apparently re-nested (Barcelo and Faaborg 2012, Brown et al 2012). It is currently (2016) a regular, localized breeder in low numbers in the Lake Ogallala area, Keith Co (Mary B. Brown, personal communication), and reports are now increasing slowly eastward; those as far east as the Columbus area may be of either subspecies. The documented eastern range extends west only to the Fremont area, Dodge Co but also appears to be expanding; two were near Royal, Antelope Co 4 Jun 2017.
In the Republican River Valley, eastern birds appear to have been established prior to the arrival of western birds; a territorial pair was seen in riparian woodland south of Orleans, Harlan Co 6 Jun 1990, three were there 23 Jun 1996, and another on 20 Jul 2000. More recent westerly reports, such as singles at Swanson Reservoir, Hitchcock Co 5 May 2003, at Oxford, Furnas Co 30 Apr 2006, and in Frontier Co 10 Jun 2009 (Brogie 2009) and 25 May 2010, were probably western birds.
- Breeding phenology:
Dates below have been separated into eastern and western reports, since different subspecies are Involved.
Nest building: 24 Apr-8 Jun
Eggs: 1 May-10 Jun
Fledglings: 26 Jun-15 Jul
Nest building: 14 May-2 Jun
Eggs: 15 Jun-1 Jul
Nestlings: 10 Jun
Fledglings: 29 Jun
Fall: summer <<<>>> Oct 2, 3, 3
Departure is usually completed by mid-Sep, although there is a later date 11 Oct 2015 Dundy Co, and an undocumented report 11 Nov 1993 Sarpy Co. Latest on record was one photographed at Lake Ogallala 25 Nov 2016.
- High counts: 12 at Carter Canyon, Scotts Bluff Co 30 Aug 2006, 12 in Long Canyon, Banner Co, 24 Aug 2008, and 11 in the Wildcat Hills, Scotts Bluff Co 4 Sep 1999.
NC: Nature Center
NNF: Nebraska National Forest
NWR: National Wildlife Refuge
SHP: State Historical Park
SP: State Park
UNSM: University of Nebraska State Museum
Photograph (top) of a Blue Gray at Fontenelle Forest, Sarpy Co 30 Apr 2008 by Phil Swanson.
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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.
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