Gulling
Gulls are often one of the last species group that birders pay attention to. Individual variation, large plumage differences between ages, sexual dimorphism, plumage abnormalities, clinal variation, the effects of bleaching and wear and even as yet unresolved taxonomy issues all combine to create a bit of a mess.
Back in 2014, I vowed to look through the thousands of gulls at Dennis Point Wharf in Lower West Pubnico until I found a first-cycle Lesser Black-backed Gull. I had previously spotted adults of this species, but while birds of the year are seperable from our more regular large, white-headed gulls, the differences are more subtle. These minute differences in feather pattern, bare part colour, size and shape are what gulling is all about. For the last 3 winters I've been spending hours and hours looking at gulls. This group of birds is fairly unique in that most of the time in the field is spent actually looking at birds, not looking for birds.
More Questions than Answers
The American Ornithological Union's 57th supplement lists Thayer's Gull (Larus thayeri) and Iceland Gull (Larus glaucoides) as distinct species, Iceland Gull comprising the Kumlien's Gull (Larus glaucoides kumlieni) and nominate (Larus glaucoides glaucoides) subspecies.
The taxonomic issues surrounding Thayer's Gull and Iceland Gull are still being discussed. I suggest that you read Taxonomic History of Thayer's Gull, a 1999 article in Ontario Birds by Ron Pittaway. Our innate need for classification of what we see becomes difficult in the case of these taxa. McLaren (2012) suggests that Thayer's Gull might best be treated as the dark extreme of a single species with Kumlien's Gull as the variable result of interbreeding with Iceland Gull. Earlier works such as Webber (1981) and Godfrey (1986) as well as a recent blog post named Thayer's the Iceland Gull - One Species by Amar Ayyash also suggest that the three taxa listed above should be conspecific:
Iceland Gull (Larus glaucoides glaucoides)
Kumlien's Gull (Larus glaucoides kumlieni)
Thayer's Gull (Larus glaucoides thayeri)
In the above classification, L.g. glaucoides becomes the nominate subspecies simply because it was described first by Meyer in 1822. Kumlien's Gull was first described in 1883 followed by Thayer's Gull in 1915.
A recent discussion on the North American Gulls Facebook Page prompted a few heavy hitters in the birding world to give their two cents. Steve Hampton, Bruce Mactavish, Peter Adriaens and Christopher Gibbins appeared to prefer the 2-species solution with Kumlien's Gull as the hybrid between Thayer's and Iceland. Some compared these species with the species pairs of Glaucous-winged Gull & Western Gull or Blue-winged Warbler & Golden-winged Warbler with their respective hybirds the Olympic Gull and Brewster's Warbler. Independent of the opinions shared by the participants, all could agree that more research is needed.
Pittaway's 1999 taxonomic history paper concluded with, "Regardless of how we classify them, they are no more or less identifiable in the field."
The apparent clinal variation from from the dark-eyed, dark-winged, less gentle proportioned Thayer's Gull to the pale-eyed, white-winged, smaller-billed and more gentle looking Iceland Gull definitely does make identification of extralimital birds difficult. I think most would agree that if it looks like a Thayer's Gull, then we can assume that this is likely linked to its provenance and/or its genetic makup. Given the current taxonomic classification of Thayer's Gull as a separate species, if a bird in Nova Scotia is found to tick all of the boxes, I wouldn't hesitate to label it as a Thayer's and add it to your Nova Scotia list as a full species.
The Pubnico Thayer's Gull
Paul Gould and I were test driving my new-to-me Subaru Forester on January 8, 2017 when we spotted a great Thayer's candidate at Dennis Point Wharf in Pubnico, Yarmouth County. We snapped a few photos and made sure to get some views of the open wing.
I didn't realize exactly how many boxes this bird ticked until I reviewed the photos at home. Here are a few reasons why this gull fits perfectly for a Thayer's Gull:
-The black on the outer primaries when viewed from above is as dark as the adjacent Herring Gulls;
-P10 has dark subterminal marks;
-The outer web of P9 is completely dark;
-There is an almost complete dark subterminal band on P5;
-The iris was dark (contrast between the pupil and iris was only visible in direct sunlight);
-The orbital ring is a deep pinkish colour;
-The head, neck and breast show a extensive blotchy brown pattern;
-The bill base is greenish-yellow;
-The legs are a pale raspberry.
This bird is immediately recognizable with the naked eye both in flight and on the water. The combination of features, most notably the dark eye, extensive hood and primary pattern are unique among the thousands of gulls at Dennis Point Wharf. It should be noted that there are many imposters as well. Kumlien's Gulls can show one or two Thayer's-like features like dark eyes, dark wings and an extensive hood, but only this bird has been found to show all of these features.
I observed this bird 4 times during January and then we were in for a great surprise when Mark Dennis spotted this exact individual at West Head on nearby Cape Sable Island, Shelburne County, on February 1, 2017. We confirmed that it was in fact the Pubnico bird because both birds had a small portion of the inner web of P5 on the left wing missing. It was then refound in Pubnico on February 4, again at Cape Sable Island on February 10 and once more in Pubnico on February 25.
References:
Pittaway, R. 1999. "Taxonomic History of Thayer's Gull". Ontario Birds 17(1):1-13.
Gulls are often one of the last species group that birders pay attention to. Individual variation, large plumage differences between ages, sexual dimorphism, plumage abnormalities, clinal variation, the effects of bleaching and wear and even as yet unresolved taxonomy issues all combine to create a bit of a mess.
Back in 2014, I vowed to look through the thousands of gulls at Dennis Point Wharf in Lower West Pubnico until I found a first-cycle Lesser Black-backed Gull. I had previously spotted adults of this species, but while birds of the year are seperable from our more regular large, white-headed gulls, the differences are more subtle. These minute differences in feather pattern, bare part colour, size and shape are what gulling is all about. For the last 3 winters I've been spending hours and hours looking at gulls. This group of birds is fairly unique in that most of the time in the field is spent actually looking at birds, not looking for birds.
More Questions than Answers
The American Ornithological Union's 57th supplement lists Thayer's Gull (Larus thayeri) and Iceland Gull (Larus glaucoides) as distinct species, Iceland Gull comprising the Kumlien's Gull (Larus glaucoides kumlieni) and nominate (Larus glaucoides glaucoides) subspecies.
The taxonomic issues surrounding Thayer's Gull and Iceland Gull are still being discussed. I suggest that you read Taxonomic History of Thayer's Gull, a 1999 article in Ontario Birds by Ron Pittaway. Our innate need for classification of what we see becomes difficult in the case of these taxa. McLaren (2012) suggests that Thayer's Gull might best be treated as the dark extreme of a single species with Kumlien's Gull as the variable result of interbreeding with Iceland Gull. Earlier works such as Webber (1981) and Godfrey (1986) as well as a recent blog post named Thayer's the Iceland Gull - One Species by Amar Ayyash also suggest that the three taxa listed above should be conspecific:
Iceland Gull (Larus glaucoides glaucoides)
Kumlien's Gull (Larus glaucoides kumlieni)
Thayer's Gull (Larus glaucoides thayeri)
In the above classification, L.g. glaucoides becomes the nominate subspecies simply because it was described first by Meyer in 1822. Kumlien's Gull was first described in 1883 followed by Thayer's Gull in 1915.
A recent discussion on the North American Gulls Facebook Page prompted a few heavy hitters in the birding world to give their two cents. Steve Hampton, Bruce Mactavish, Peter Adriaens and Christopher Gibbins appeared to prefer the 2-species solution with Kumlien's Gull as the hybrid between Thayer's and Iceland. Some compared these species with the species pairs of Glaucous-winged Gull & Western Gull or Blue-winged Warbler & Golden-winged Warbler with their respective hybirds the Olympic Gull and Brewster's Warbler. Independent of the opinions shared by the participants, all could agree that more research is needed.
Pittaway's 1999 taxonomic history paper concluded with, "Regardless of how we classify them, they are no more or less identifiable in the field."
The apparent clinal variation from from the dark-eyed, dark-winged, less gentle proportioned Thayer's Gull to the pale-eyed, white-winged, smaller-billed and more gentle looking Iceland Gull definitely does make identification of extralimital birds difficult. I think most would agree that if it looks like a Thayer's Gull, then we can assume that this is likely linked to its provenance and/or its genetic makup. Given the current taxonomic classification of Thayer's Gull as a separate species, if a bird in Nova Scotia is found to tick all of the boxes, I wouldn't hesitate to label it as a Thayer's and add it to your Nova Scotia list as a full species.
The Pubnico Thayer's Gull
Paul Gould and I were test driving my new-to-me Subaru Forester on January 8, 2017 when we spotted a great Thayer's candidate at Dennis Point Wharf in Pubnico, Yarmouth County. We snapped a few photos and made sure to get some views of the open wing.
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| Here is a photo from our first encouter with the Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, January 8, 2017. Photo by Alix d'Entremont. |
I didn't realize exactly how many boxes this bird ticked until I reviewed the photos at home. Here are a few reasons why this gull fits perfectly for a Thayer's Gull:
-The black on the outer primaries when viewed from above is as dark as the adjacent Herring Gulls;
-P10 has dark subterminal marks;
-The outer web of P9 is completely dark;
-There is an almost complete dark subterminal band on P5;
-The iris was dark (contrast between the pupil and iris was only visible in direct sunlight);
-The orbital ring is a deep pinkish colour;
-The head, neck and breast show a extensive blotchy brown pattern;
-The bill base is greenish-yellow;
-The legs are a pale raspberry.
 |
| This image shows well the primary pattern of the Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, January 14, 2017. P10 has dark subterminal marks between the mirror and apical spot; the outer web of P9 is completely dark; there is an almost complete dark subterminal band on P5. Photo by Alix d'Entremont. |
 |
| Here we get a look at the pale underside of the outer primaries of the Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, January 14, 2017. This is quite different from that of a Herring Gull. Photo by Alix d'Entremont. |
 |
| This image allows for comparison of a Herring Gull with the Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, January 14, 2017. Note how the black on the outer primaries is of equal darkness on both gulls. The Thayer's shows a dark eye and greenish-yellow based bill in contrast with the pale yellow iris and orangish-yellow based bill of the Herring. Photo by Alix d'Entremont. |
 |
| Here we see the pale raspberry legs of the Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, January 14, 2017. Photo by Alix d'Entremont. |
This bird is immediately recognizable with the naked eye both in flight and on the water. The combination of features, most notably the dark eye, extensive hood and primary pattern are unique among the thousands of gulls at Dennis Point Wharf. It should be noted that there are many imposters as well. Kumlien's Gulls can show one or two Thayer's-like features like dark eyes, dark wings and an extensive hood, but only this bird has been found to show all of these features.
I observed this bird 4 times during January and then we were in for a great surprise when Mark Dennis spotted this exact individual at West Head on nearby Cape Sable Island, Shelburne County, on February 1, 2017. We confirmed that it was in fact the Pubnico bird because both birds had a small portion of the inner web of P5 on the left wing missing. It was then refound in Pubnico on February 4, again at Cape Sable Island on February 10 and once more in Pubnico on February 25.
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| The Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, February 4, 2017. Photo by Alix d'Entremont. |
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| The Thayer's Gull at Dennis Point Wharf in Pubnico, Nova Scotia, February 4, 2017. Photo by Alix d'Entremont. |
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| The Thayer's Gull with two Kumlien's Gulls (adult and first-cycle) at Dennis Point Wharf in Pubnico, Nova Scotia, February 4, 2017. Photo by Alix d'Entremont. |
References:
1986. The Birds of Canada. Revised Edition. National Museums of Canada, Ottawa.
McLaren, I.A. 2012. All the Birds of Nova Scotia: status & critical identification. Gaspereau Press Ltd, Kentville, N.S., Canada
Pittaway, R. 1999. "Taxonomic History of Thayer's Gull". Ontario Birds 17(1):1-13.
Weber J.W. 1981. The Larusgulls of the Pacific Northwest Interior, with
taxonomic comments on several forms (Part 1). Continental Birdlife 2(1): 110.
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