Sunday, February 1, 2015

Nelson's Gull

My uncle, Ronnie d'Entremont, found a dark Glaucous Gull at Dennis Pt Wharf in Pubnico on January 31, 2015 that was identified as a probable Glaucous Gull x Herring Gull hybrid. This species combination is frequent enough that it has been given a name, Nelson's Gull.

Iceland Gull (L) and Nelson's Gull (R) Photo by Alix d'Entremont

Glaucous Gulls and Herring Gulls interbreed in both north-east and north-west Canada. This gull is likely an eastern bird where the hyperboreus subspecies of Glaucous Gull hybridizes with Herrings (Howell et al., 2007). The other North American subspecies of Glaucous Gull that winters in North America is L. h. barrovianus. This subspecies breeds in coastal Alaska to northern Yukon and winters to coastal California, making it unlikely to occur in the east (Pyle, 2008).

Nelson's Gulls are usually intermediate between the parent species. Some first cycle hybrids can be very similar to a Herring Gull but have browner wingtips and more pale on the inner webs of the outer primaries (Howell et al., 2007). Others resemble Glaucous Gulls but show a Herring like pattern to the outer primaries and a darker tail (Peregrine Prints, 2015).

This gull looks most similar to a Glaucous Gull but shows outer primaries, secondaries and tail that are washed brown in a pattern reflecting that of a Herring Gull. The next photo shows the hybrid at left compared to our typical Glaucous Gull at right. Notice how the Nelson's Gull is much browner overall with wingtips that are washed brown.

Nelson's Gull (L) and Glaucous Gull (R) Photos by Alix d'Entremont

Howell et al. (2007) describe first cycle Glaucous Gulls as pale brownish to creamy overall with whiter wingtips. The following photo shows marked difference between the Nelson's Gull and a Glaucous Gull. Instead of having comparatively pale wingtips, the Nelson's shows darker wingtips. The dark secondaries and tail are also evident in this photo.

Nelson's Gull (L) and Glaucous Gull (R) Photos by Alix d'Entremont

Dennis Pt Wharf in Pubnico is a gull watchers dream. I tried to find this Nelson's Gull on January 31, 2015 and ended up finding two pure Glaucous Gulls and a Lesser Black-backed with over 150 Iceland Gulls. We will keep looking and will keep finding interesting gulls here.

Howell, S.N.G. and J. Dunn. 2007. Gulls of the Americas. Houghton Mifflin Company, New York, N.Y.

Pyle, P., S.N.G. Howell, S. Ruck, and D.F. Desante. 2008. Identification guide to North American birds, Part II, Anatidae to Alcidae. Slate Creek Press, Bolinas, California.

Peregrine Prints. February 2015.

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