Aechmophorus occidentalis x AECHMOPHORUS clarkii
Status: Rare regular spring and fall migrant west and west central. Rare casual breeder Keith Co.
Documentation: Photograph: 25 May 2020 Box Butte Reservoir SRA, Dawes Co (Leukering, Dunning; eBird.org).
Taxonomy: Hybridization occurs between the two Aechmophorus species. Konter (2011) found around 3.5% of birds in sympatric breeding populations in California and Oregon were intermediate, and that the percentage of intermediates had increased since earlier studies (Ratti 1979, 1981). Nevertheless, Konter (2011) found sufficient assortative mating between the two species to continue to consider them separate species. Pyle (2008), however, considered the two conspecific.
Bill color and location and extent of black feathering relative to the eye are key features to note when identifying hybrids. Ratti (1981) noted that bill color is “not as discrete as the facial pattern” and “alone should not be used to identify these species.”
Among the first reports of hybrids are 1-2 at Lake McConaughy, Keith Co 18 Apr and 9 May 1998, 15 Aug 1997 North Platte NWR, Scotts Bluff Co, and 27 Sep 1996 Lake McConaughy.
Spring: There are nine records: 18 Apr 1998 Lake McConaughy, 19 Apr 2020 Lake Minatare, Scotts Bluff Co (Leukering, eBird.org), 25 Apr 2022 Lake Minatare, Scotts Bluff Co, 30 Apr 2018 Lake McConaughy (Strand, Smith; eBird.org), 1 May 2020 Lake Alice, Scotts Bluff Co (Leukering, Dunning, eBird.org), 9 May 1998 Lake McConaughy, 14 May 2021 North Platte WTP, Lincoln Co (Mlodinow, eBird.org), 14 and 23 May 2024 Cedar Vue, Lake McConaughy, 25 May 2020 Box Butte Reservoir SRA, Dawes Co (Leukering, Dunning, eBird.org).
In addition, a later record was of one at Scottsbluff WTP, Scotts Bluff Co 9 Jun 2023.
Summer: A young hybrid was being carried by an adult, one of a pairing of Western Grebe and a hybrid, at Lake McConaughy, Keith Co 2 Jul 2024 (Mlodinow, eBird.org).
Fall: Sep 3, 3, 3 <<<>>> Oct 14, 16, 17
Earlier dates are 10 Aug 2019 Crescent Lake NWR, Garden Co, and 15 Aug 1997 North Platte NWR, Lincoln Co, and later dates 23 Oct 2023 Lake Minatare, Scotts Bluff Co, 29 Oct 2021 Sutherland Reservoir, Lincoln Co, 18 Nov 2024 Lake McConaughy, Keith Co, and 27 Nov 2014 Dodge Co.
There are about 25 records, most at fall staging areas for Western and Clark’s Grebes like Lake McConaughy and lakes within North Platte NWR, Scotts Bluff Co.
A high count of 11 was achieved on a Lake McConaughy “pelagic” 26 Sep 2024.
Images
Literature Cited
Konter, A. 2011. Interbreeding of Aechmophorus grebes. Wilson Journal of Ornithology 123: 132-136.
Pyle, P. 2008. Identification Guide to North American Birds. Part II, Anatidae to Alcidae. Slate Creek Press, Bolinas, California, USA.
Ratti, J.T. 1979. Reproductive separation and isolating mechanisms between sympatric dark- and light-phase Western Grebes. Auk 96: 573-586.
Ratti, J.T. 1981. Identification and distribution of Clark’s Grebe. Western Birds 12: 41-46.
Recommended Citation
Silcock, W.R., and J.G. Jorgensen. 2024. Western Grebe x Clark’s Grebe (Aechmophorus occidentalis x clarkii). In Birds of Nebraska — Online. www.BirdsofNebraska.org
Updated 4 Dec 2024