156 Nikon Photo Quiz Sponsored by Nikon Canada

Nikon www.nikon.ca 157 December 2003 Quiz

Glenn Coady

In late fall and early winter, many as they proceed from juvenile to Ontario birders turn their thoughts adult age classes, and you have a to the challenges presented by the group of birds that may serve as an abundant concentrations of gulls to excellent learning tool for honing be found at our favourite birding identification skills for the beginner haunts after their post-breeding dis­ and intermediate birder, as well as a persal to wintering areas. Twenty constant source to challenge any gull species have been found in tendency toward complacency in Ontario thus far, and at least a even the most expert birder. handful of additional species are Our quiz presents a lone gull good candidates to be added to our for analysis without any gulls of checklist yet. Add to this the fact easily determined identity with that all of these gulls exhibit a which to make basic comparisons sequence of often subtly unique for an assessment of overall size plumages and soft part appearances and proportions.

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VOLUME 21 NUMBER 3 158

Even without having a good This gull is definitely not dark reference for the size of this bird, enough for a Heermann's Gull in we can tell from its rather short, first basic plumage, and the light thin and distinctly pointed bill and grey mantle at this age is sufficient its delicately rounded head shape, to easily exclude Ivory Gull. that this bird is not likely one of the The quiz bird shows mostly larger, white-headed gulls that take brownish legs with some orange four years to reach maturity. These tones, and a predominantly orange­ gulls, even as juveniles, all present a pink bill with a dark tip. A first basic much thicker bill structure, with a Black-legged Kittiwake would culmen that curves sharply down­ show all black feet and legs and an ward near the end, presenting a all-dark bill, and can thus be elimi­ much duller, flatter, more hooked nated from further consideration. tip. They also tend to show a more Similarly, Sabine's Gull is very prominent gonydeal angle than this unlikely to ever be found in bird. Hence, based on these struc­ Ontario in first basic plumage; it tural clues alone, we can quickly usually completes its first prebasic and intuitively eliminate California molt on its southern hemisphere Gull, Herring Gull, Thayer's Gull, wintering grounds. In any event, Iceland Gull, Glaucous Gull, Lesser both juvenile and first basic Black-backed Gull, Slaty-backed Sabine's Gull would show an all­ Gull and Great Black-backed Gull, black bill and a darker nape than without even so much as a look at our quiz bird, thus ruling it out as plumage characters. Conversely, well. First basic individuals of both this bird's bill is both far too long of the medium-sized hooded gulls, and too thick for that of a Ross's Laughing Gull and Franklin's Gull, Gull, the most diminutive-billed would demonstrate a considerably gull, which we also may eliminate darker mantle than the quiz bird easily. and would have much more uni­ One of the first things we formly darker bills and darker legs. notice about this bird is that it has a Additionally, Franklin's Gull would uniformly light grey mantle which show a partial hood. Both of these contrasts with the more brownish gulls thus can be dismissed also. lesser coverts and the dark brown Looking at our quiz bird's tertials. Among the small to medi­ head pattern, we can note that it urn-sized gulls left to consider, this shows a mostly white head with a pattern should let us confidently light grey "ear spot" and dark age this as a first basic (first winter) plumage around the eye. These are bird that has mostly completed its more characteristic of one of the first prebasic (postjuvenile) molt. small hooded gulls rather than the Knowing this, we can now eliminate pattern of overall fine streaking on several other Ontario gull species. the head, nape and upper breast ONTARIO BIRDS DECEMBER 2003 159 expected on first basic individuals not show as much of the primaries of the smaller white-headed species beyond the tertials as the quiz bird such as Mew Gull and Ring-billed which easily shows fully five pri­ Gull. maries beyond the tertiaIs, a charac­ We are left with only three ter very unlikely to be seen with the small hooded gulls from the species shorter and rounder-winged Little found in Ontario: Little Gull Gull. Bonaparte s Gull and Black-head­ As far as the soft parts of our ed Gull. quiz bird are concerned, they are a Of these species, we are able to better match for Black-headed Gull eliminate Little Gull most easily as than Bonaparte's Gull. The latter a possibility. Little Gull should have generally has an all-black bill and a much finer and shorter, all-black should not show such a pale bill in comparison to the quiz bird. orange-pink base to the bill or such In first basic plumage, it should a two-toned effect. Also, show a darker and more solid and Bonaparte's Gull has a slightly finer extensive carpal bar in the lesser bill than the quiz bird. First basic coverts, and unlike our quiz bird, it Bonaparte's Gulls tend to have should demonstrate a dark cap. A lighter pink legs than Black-headed Little Gull with wings folded would Gulls (although this is variable and ~EAGLE~ ""OPTICS.CA

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VOLUME 21 NUMBER 3 160

extends up onto the nape in The Bonaparte's Gull normally, whereas usually Black-headed Gull in first DovetaD basic shows a distinct contrast between the grey mantle and its Directory whitish nape. Once again, the pat­ tern on the quiz bird is more consis­ tent with Black-headed Gull rather than Bonaparte's Gull for these features. Indeed, our quiz bird is a first basic Black-headed Gull that was photographed by Roy Smith on The world's largest catalogue 27 March 2001 at Chew Valley ofcomplete birding and Lake, England. nature tour itineraries If we could examine this bird in flight, or at least with out­ Forty-five independent operators stretched wings, additional points of Several hundred itineraries confirmation would be Black-head­ ed Gull's dark undersides to the Truly, your one-stop shop! primaries, its all-dark secondaries www.dovetaildirectorv.com and inner primaries (these are dark-tipped only in first basic prone to lighting artifacts) and usu­ Bonaparte's Gull), and its generally ally considerably shorter legs as browner carpal bar through the well. The quiz bird's orange-brown lesser coverts. legs appear quite long also and are Black-headed Gull breeds as likely a better match for Black­ close as the Magdalen Islands in headed Gull. Bonaparte's Gulls Quebec and in western Newfound­ tend to have darker "ear spots" land, and is a species that could than Black-headed Gulls. Our quiz potentially appear anywhere in bird shows a fairly pale brown ear Ontario. Although sightings on the spot much lighter than the eye, a lower Great Lakes predominate, so feature supporting Black-headed does coverage. However, it should Gull. First basic Bonaparte's Gull be more expected, probably, on the has a slightly darker grey mantle lower lakes via the seaway, and it shade than that of Black-headed occurs annually in very small num­ Gulls of the same age. The grey bers.

Glenn Coady, 604-60 Mountview Avenue, Toronto, Ontario M6P 2L4

ONTARIO BIRDS DECEMBER 2003