Saturday, February 21, 2015

Hoary Redpoll

The two species of redpoll are similar, but careful study is usually diagnostic. Nova Scotia's regular species is the Common Redpoll (Acanthis flammea) while the Hoary Redpoll (Acanthis hornemanni) nests farther north and is much rarer. Pyle (2007) recognizes two subspecies for each, A.f. flammea and A.f. rostrata for Common and A.h. hornemanni and A.h. exilipes for Hoary. McLaren (2012) states that we observe mainly flammea Common Redpolls and exilipes Hoary in our province - this article will focus on these two subspecies.

On February 4, 2015 I found a redpoll that stood out from the group at Laurel Amirault's feeder in Lower West Pubnico, Yarmouth County. It was clearly much paler than the Common Redpolls that it was travelling with. This bird was my first Hoary Redpoll (Fig. 1).

Figure 1. Hoary Redpoll in Pubnico - Feb 4, 2015 - Photo by Alix d'Entremont

Confidently identifying a Hoary Redpoll in a flock of Common Redpolls requires analysis of a number of characteristics, some of which are quite subtle. Fig. 2 shows how the Hoary Redpoll is paler overall as compared to the two Common Redpolls. There is plumage variation in both species, but first-winter birds are consistently darker than the adults. The infusion of buff in the face, molt limit in the greater coverts and tapered outer rectrices of this bird make it a first-winter. This immature bird is considerably lighter than the nearby adult male Common Redpolls (the palest sex and age of that species) in other photographs, providing strong evidence in favour of first-winter Hoary rather than first-winter Common.

Most field guides illustrate a few other major differences. Sibley (2014) mentions the bold white edging to the secondaries, stubby bill and fine underside streaking of a Hoary that are all appreciable in Fig. 2. Hoaries often look larger due to their tendency to fluff their feathers, but they are extremely similar in size (McLaren, 2012). The Hoary in Fig. 2 looks much more plump than the Commons due to its fluffed up feathers.

Figure 2. Hoary Redpoll with Commons and a Goldfinch in Pubnico - Feb 4, 2015 - Photo by Alix d'Entremont

The relatively stubby bill of the Hoary Redpoll is evident in Fig. 3. Pyle (1997) gives us another way to appreciate this bill difference by describing the comparatively longer bill of a Common as more acutely angled versus the obtuse bill tip of a Hoary.  Hoary Redpolls typically show less extensive black in the chin and lores (Brinkley et al., 2011). Fig. 3 also shows how the light crown of the Hoary contrasts much more with the red forehead.

Figure 3. Hoary Redpoll (L) vs. Common (R) - Feb 4, 2015 - Photo by Alix d'Entremont

Hoary Redpolls show no or very limited streaking on the undertail coverts while Common Redpolls have more extensive streaking. First winter birds show the most pronounced streaking for each species. The longest undertail covert of first-winter Commons have heavy and distinct streaks while Hoary shows no or narrow streaks. Fig. 4 shows the single narrow streak found on the undertail coverts as is expected for a first-winter Hoary. (Pyle, 1997)

Figure 4. Hoary Redpoll in Pubnico - Feb 4, 2015 - Photo by Alix d'Entremont

A very useful article that appeared in North American Birds called Photo Essay: Redpolls from Nunavut and Greenland visit Ontario is available online as a PDF. It describes the four redpoll subspecies with text and photos and is worth reading in preparation for your next redpoll flock.

Brinkley, E.S., Buckley, P.A., Bevier, L.R. and A.M. Byrne. 2011. Photo Essay: Redpolls from Nunavut and Greenland visit Ontario. North American Birds 65(2): 2-11

Pyle, P., S.N.G. Howell, R.P. Yunick, and D.F. Desante. 1997. Identification guide to North American Birds, Part 1, Columbidae to Ploceidae. Slate Creek Press, Bolinas, California.

McLaren, I.A. 2012. All the Birds of Nova Scotia: status & critical identification. Gaspereau Press Ltd, Kentville, N.S., Canada

Sibley, D.A. 2014. The Sibley Guide to Birds 2nd Ed. Alfred A. Knopf, New York, N.Y.

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.