Phalacrocorax auritus auritus
Status: Abundant regular spring and fall migrant statewide. Locally common regular breeder north and west, rare casual elsewhere. Locally uncommon regular summer visitor away from breeding range locations. Rare casual winter visitor south.
Documentation: Specimen: UNSM ZM7651, 1 Nov 1932 North Platte, Lincoln Co.
Taxonomy: Four subspecies are recognized (Gill and Donsker 2017), auritus of the North American Interior and east to the northern Atlantic coast, floridanus of the southern Atlantic coast, Florida, Bahamas, and Cuba, albociliatus of the Pacific Coast from British Columbia to the Gulf of Mexico, and cincinatus of the Aleutian Islands and southern Alaska. Nebraska birds are presumed auritus.
Spring: Feb 27,28, Mar 2 <<<>>> May 31,31, Jun 1
There are earlier reports of nine on 14 Feb 2017 Holmes Lake, Lincoln, Lancaster Co, 35 on 17 Feb 2017 over Indian Cave SP, Richardson and Nemaha Cos, 18 Feb 2017 Hiatt Wetlands, North Platte, Lincoln Co, 20 Feb 1991 Douglas-Sarpy Cos, and 23 Feb 1958 Lincoln Co.
Movement normally commences in late Mar and peaks in early to mid-Apr, but there are several late spring reports into summer of non-breeding immatures.
- High counts: 6000 at Branched Oak Lake, Lancaster Co 15 Apr 2017, 5000 near Odessa, Buffalo Co 4 Apr 2004, and 5000 in Lancaster Co 13 Apr 2007.
Summer: Around 1900 breeding was unknown (Bruner et al 1904), but by the 1950s Rapp et al (1958) listed Scotts Bluff, Garden, Keith, Cherry, Grant, and Lincoln as counties where breeding had occurred. Ducey (1988) presented no breeding records prior to 1921 but added Sheridan Co to the list of Rapp et al (1958).
Breeding occurs regularly at Crescent Lake NWR, Garden Co and Valentine NWR, Cherry Co. A total of 43 nests were located at Crescent Lake NWR 15 May 2006, and 40+ were occupying nests at Pony Lake, Valentine NWR 26 May 2007. Nesting occurred in 2006 at Cottonwood-Stevenson WMA, Grant Co.
Elsewhere, breeding is sporadic, as breeding habitat of trees in standing water tends to be ephemeral.
Nesting occurs in the Lake McConaughy area, Keith Co, but on a much smaller scale and only sporadically compared to when Kingsley Dam was under construction; the flooded dead trees attracted a peak of 228 nests and 1000 birds in the 1940s (Collister 1948, Rosche 1994). The first nest here since the 1940s was just below Kingsley Dam 28 Apr 2007; two nests and 200-250 cormorants were there 10 Jun. Although 97 cormorants were at Lake Ogallala 7 Jun and “hundreds” were there 18 Jun 2008, and in 2009 an estimated 100 cormorants were there, no nests were found either year. This colony appeared to be abandoned in 2017.
In Scotts Bluff Co, breeding occurred at Lake Alice, North Platte NWR a few years prior to 2015, and “2-3 giant cottonwoods were full of nests” along the North Platte River just downstream of the Morrill bridge 20 May 2011 (Andrew Pierson, personal communication).
There are several nesting reports in the eastern Sandhills. Breeding occurred in 1988 in Rock Co, where 29 nests were counted (Bennett 1989) and in 1997 nesting was noted at Lake George (eight nests), and Twin Lakes (two nests), both sites in Rock Co. Nesting probably occurred at Swan Lake, Holt Co, in 1988 (Blake and Ducey 1991).
Nesting has occurred sporadically at the west end of Harlan Co Reservoir, where nine nests were noted in 1995, at least 26 nests in 1996, and as many as 73 birds were on nests in 2001. Low water in 2002 and 2003 precluded nesting there, however, and by 2005 most of the nest trees had been blown down. Again in 2009, around 75 birds were present, with 25+ nests 29 Apr in live trees. In 2010 none were present until 32 appeared 11 Jul, and in 2011, as many as 55 birds were at the lake, but no nesting was observed.
The first Rainwater Basin nesting record involved two pairs building nests in small willows at Harvard WPA, Clay Co 19 Jul 2015, and incubating by 26 Jul, when two additional nests were being built (Jorgensen 2015). The four nests were abandoned by 26 Aug, possibly due to the ending of a temporary irruption in the local frog (Pseudacris spp.) population.
Non-breeders, mostly immatures, are common throughout the north and west in mid-summer but are uncommon and local in the south and east, with fewest reports in Jun and early Jul. Reports of summering non-breeders are annual from favored locations such as Branched Oak Lake and Harlan Co Reservoir. Peak count at Branched Oak Lake in 2017 was 23 on 23 Jun.
- Breeding Phenology:
Eggs: 8 May-21 Jun
Nestlings: 5-19 Jun
Fall: Jul 11,12,12 <<<>>> Dec 22,22,24
Early dates above are for areas away from the breeding range. Peak numbers pass through in Oct, and high counts occur at favored staging areas such as Calamus Reservoir, Loup Co, where 7500 were present 15 Oct 2012 (Dinan and Jorgensen 2014). Later reports, some probably of birds attempting to winter, are 27 Dec 2014 Lake McConaughy, 27-28 Dec 2006 Lake McConaughy, 29 Dec 1993 Cass Co, 30 Dec 1994 Harlan Co Reservoir, 30 Dec 2015 Calamus-Loup CBC, and 1-2 through 8 Jan 1998 at Branched Oak Lake.
- High counts: 12,000 at Harlan Co Reservoir 5 Oct 2008, 10,000 there 14 Oct 2011, and 7500 at Calamus Reservoir 15 Oct 2012 (Jorgensen and Dinan 2014).
Winter: Cormorants typically are not present during winter. However, at Sutherland Reservoir, Lincoln Co, a cooling pond remains open in winter due to water releases from a coal-fired power station. Overwintering was first noted there in 1995-96, but the four birds there 22 Dec dwindled to one by 13 Jan. Since then, overwintering has occurred most years; best winter count is the 24 there 29 Dec 2018, although only four were still there 10 Feb 2019. A maximum of 20 were wintering there 2014-2015 along with up to 24 American White Pelicans and even Nebraska’s first wintering Brown Pelican.
Elsewhere, reports of overwintering are few. At least one wintered and 9-15 were present 14- 15 Feb at Harlan Co Reservoir 1999-2000, another was there 22 Jan 2012, and an injured bird survived at Lake McConaughy at least until 29 Jan 2000. An immature wintered at Hiatt Memorial Wetlands, North Platte, Lincoln Co 2012-2013. A group of 10-14 may have wintered at Branched Oak Lake, Lancaster Co 2015-2016; although 14 were there 12 Jan, none were reported subsequently.
Additional midwinter reports are 6 Jan 2019 Lake McConaughy, 12 Jan 1992 Lancaster Co, 16 Jan 1999 Harlan Co Reservoir, 29 Jan 2000 Cunningham Lake, Douglas Co, 30 Jan 1972 at Lake McConaughy (Rosche 1994), and 9 Feb 2003 Johnson Lake, Gosper Co.
Comments: Double-crested Cormorants have increased throughout their range in recent decades. Consequently, conflicts between sport fish angling interests and American White Pelicans and Double-crested Cormorants have increased in number and intensity. In parts of the United States, Double-crested Cormorant numbers are lethally controlled to reduce impacts to property or sport fish resources through federal depredation orders (50 CFR 21.48). Concerns over impacts to sport fish resources have also been raised in Nebraska. This issue was explored by Dinan and Jorgensen (2014), who provided baseline count data on these species in the Sandhills in fall 2012 and concluded Double-crested Cormorants are unlikely to be negatively affecting sport fish resources in the state.
NWR: National Wildlife Refuge
SP: State Park
UNSM: University of Nebraska State Museum
WMA: Wildlife Management Area (State)
Bennett, E.V. 1989. 1988 Nebraska nesting report. NBR 57: 34-41.
Blake, L., and J. E. Ducey. 1991. Birds of the eastern Sandhills in Holt County, Nebraska. NBR 59: 103-132.
Bruner, L., R.H. Wolcott, and M.H. Swenk. 1904. A preliminary review of the birds of Nebraska, with synopses. Klopp and Bartlett, Omaha, Nebraska, USA.
Collister, A. 1948. Nesting of the Double-crested Cormorant in Nebraska. NBR 16: 22-26.
Dinan, L.R., and J.G. Jorgensen. 2014. Double-crested Cormorant and American White Pelican abundance at Sandhills lakes during fall migration. NBR 82: 73-80.
Ducey, J.E. 1988. Nebraska birds, breeding status and distribution. Simmons-Boardman Books, Omaha, Nebraska, USA.
Gill, F., and D. Donsker (Eds). 2017. IOC World Bird List (v 7.3), accessed 30 January 2018.
Jorgensen, J.G. 2015. Cormorants nesting in Rainwater Basin. Nongame Bird blog post, accessed 30 April 2018.
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.
Rosche, R.C. 1994. Birds of the Lake McConaughy area and the North Platte River valley, Nebraska. Published by the author, Chadron, Nebraska, USA.
Silcock, W.R., and J.G. Jorgensen. 2018. Double-crested Cormorant (Phalacrocorax auritus auritus), Version 1.0. In Birds of Nebraska — Online. www.BirdsofNebraska.org