Aechmophorus occidentalis x clarkii
Status: Rare regular spring and fall migrant west and west central.
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.”
Early reports of hybrids/intermediates are 1-2 at Lake McConaughy, Keith Co 18 Apr and 9 May 1998, 15 Aug 1997 North Platte NWR, Scotts Bluff Co, 27 Sep 1996 Lake McConaughy, Keith Co, and 27 Nov 2014 Dodge Co.
Spring: There are eight 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, Keith Co (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), 25 May 2020 Box Butte Reservoir SRA, Dawes Co (Leukering, Dunning, eBird.org).
Fall: Sep 3, 3, 3 <<<>>> Oct 13, 13, 16
Earlier dates are 10 Aug 2019 Crescent Lake NWR, Garden Co, and 15 Aug 1997 North Platte NWR, Lincoln Co, and later dates 29 Oct 2021 Sutherland Reservoir, Lincoln Co, and 27 Nov 2014 Dodge Co.
There are 16 records, most at fall staging areas for Western and Clark’s Grebes like Lake McConaughy and lakes within North Platte NWR, Scotts Bluff Co.
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.
Silcock, W.R., and J.G. Jorgensen. 2021. Western Grebe x Clark’s Grebe (Aechmophorus occidentalis x clarkii). In Birds of Nebraska — Online. www.BirdsofNebraska.org
Updated 30 Mar 2022