The most unusual and unexpected record on this list would have to be Western Gull. That may sound surprising at first, but Western Gull is quite sedentary and is not regularly found more than 100 miles or so from the Pacific Coast - the others on the list are prone to vagrancy.
Here's the account as given in "The Birds of Illinois" by H. David Bohlen: "A Western Gull was seen in Lincoln Park, Chicago, on October 19, 1927, and was collected on November 17. It was a near-adult male, identified as a member of the L.o. wymani race (Wright and Komarek 1928)." After going through the hands of several ornithologists, Dr. Jonathan Dwight finally gave it the seal of approval, labeling it a Western.
With this being the first eastern-most WEGU record in North America, I decided to take a closer look at it. Fortunately, the specimen number and the institution that houses this bird were given by Bohlen (which made my job much easier). To make a long story short, I recently found myself searching through gull skins at the Chicago Academy of Science with Collections Manager, Dawn Roberts.
Here's the Chicago specimen:
My first reaction to Dawn was, "This is bad. This isn't good for a pure Western Gull."
Of the large gulls, Western adults are among the most white-headed, even through periods of molt when most other species acquire "dirty" heads. A quick peek at "Western Gull" in the complete Sibley field guide will give you a good idea of the amount of head markings typically expected on this species. Extensive cloudy head markings, such as those shown on this specimen, suggest introgression with Glaucous-winged (see the Glaucous-winged x Western hybrid on p. 204 in your Sibley guide). In addition, these Western look-alikes tend to show paler grays on the upperparts -something else that's noticeable on the Chicago bird.
While examining the specimen, I had a piercing feeling that told me I had seen this bird before. I soon recalled a similar discussion that took place on the Illinois Birders Forum last winter regarding Westerns and head markings. When I got home, I spent about 5-10 minutes searching for the thread on the forum. Sure enough, longtime Chicago birder, Robert D. Hughes, had called this same specimen into question (to read this discussion, click here). Had I known at the time that this was once a live bird that was observed in the field, and the "only" accepted Western record for Illinois, I surely would have pursued it then. Bohlen's account is of a near-adult and this is what I speculated from the photos on the forum. With the bird in hand, I looked for signs of immaturity. Besides the bill pattern that Hughes mentions, I found a subadult uppertail covert with sparse barring, confirming a less-than definitive adult:
Although, the specimen is labeled "Ad."(adult) and originally classified as L.o. wymani (the southern race of Western Gulls), it appears someone took the time to study this skin in 1971, labeling it L.o. occidentalis (the nominate race). Whoever reexamined this bird was getting warmer; Recall that the nominate race averages darker eyes, slightly paler upperparts and slightly heavier head streaking - but never to this extent and not this particular pattern!
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| Smudgy head markings are commonly shown by Glaucous-winged and its hybrids. |
During a recent visit to Seattle, I was in the company of gull aficionado Michael Donahue who suggested that the bird shown below is better left as a hybrid due to its head markings:
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| Presumed adult Western x Glaucous-winged. Note the cloudy head markings that are atypical for pure Westerns. Also, the upperparts and primaries seem too pale. Tukwila, WA. 01 January 2012. |
To me, this head streaking was moderate, but to Donahue, these markings were the first hint of hybridism. Admittedly, most Washingtonians are rather conservative when it comes to labeling pure Westerns, and who could blame them? Much of their population of Westerns and Glaucous-wingeds is more or less part of a gene pool of backcrosses. The Northern race of WEGU (L.o. occidentalis) hybridizes extensively with Glaucous-winged Gull along the coasts of Oregon and Washington state. This extensive hybridizing has partly contributed to a race of Northern Westerns that have slightly paler upperparts and darker irides than their Southern counterparts. Of the hundreds of Western-types that I observed in Washington, these two were among the small handful that showed white heads and darker upperparts:
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| Unmarked head, jet-black primaries, darker upperparts and bright bill are very suggestive of a pure Western Gull. Darker eye hints at the Northern race, W.o. occidentails. Gray's Harbor, WA. 02 January 2012. |
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| Same features as individual shown above but with some head markings that are within the limits of a pure WEGU. Ocean Shores, WA. 02 January 2012. |
An excellent source for "typical" head markings on 4th cycle WEGU is "Gulls of the Americas" by Howell & Dunn (see plate 1.74, p.42; plate 1.77, p.43; plate 31.1, p.221). A possible 4th cycle Western is shown on p.43 and is suspected of being less than pure (the individual shown in the gull guide has less head markings than the specimen in question). Of their bird, Howell & Dunn note the following, "This may represent maximum midwinter head and neck markings of pure birds".
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I'd like to emphasize that there are various traits that can be combined or used singly on these hybrid individuals of the Pacific Northwest (to see more photos, click here). One should not necessarily expect a perfectly looking intermediate bird when examining a suspected Western x Glacous-winged, and this is due to the prevalent backcrossing throughout this "hybrid zone". As noted in Gulls of the Americas, "Many birds are clearly intermediate between the parent species, but other hybrids are more subtle" (p.479).
Take for example this known-age, known-hybrid, Western x Glaucous-winged that I photographed earlier this year in Washington:
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| 8-year old adult Western x Glaucous-winged hybrid from the Tatoosh Island Colony. Photographed in Gray's Harbor, WA on 02 January 2012. |
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| Same individual as above. |
After doing a little homework, I learned that this hybrid was banded as a chick on Tatoosh Island (a known colony in far Northwest Washington with much hybridizing and backcrossing). It was logged under a "mixed-pair" clutch and I was told that one of its siblings was collected in 2009. Overall, the bill, upperpart coloration and primary pattern of the bird pictured above seem very acceptable for a pure Western, but the head markings are unquestionably disturbing! To assist in ruling out a pure bird in the field, consider the orbital ring as well. These hybrids (so called Olympic Gulls) consistenly show a blend of pink and yellow in their orbitals:
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| Note the cloudy head markings and mixed orange/pink orbital ring - both are typical marks shown on hybrid individuals. |
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| Laguna Lake, CA. 15 January 2010. Pure Western Gull with limited head markings and completely yellow orbital ring. |
In conclusion, I would humbly propose that the Chicago specimen be marked with an asterisk and that the "first state record" of a pure Western Gull is abrogated. Arguably, it resembles a Western Gull more than it does a Glaucous-winged and is not likely a first-generation hybrid. The upperparts are suspiciously pale, and this is probably why the 1971 handler revised the subspecies to the nominate race, occidentalis. Most importantly, the extensive head, neck and breast markings are beyond the limits of a pure Western Gull in its 4th cycle. I don't doubt that Westerns can stray from the Pacific, but we should strive for a sound record with this taxon; Its great propensity for hybridizing with Glaucous-winged should not be ignored, especially in the case of an extralimital record. It's important to bare in mind that records such as this can be misleading when other states investigate the likelihood of Westerns vagrating far from the Pacific Coast. Unfortunately, the Chicago record was indeed used as support for a suspected WEGU that roamed the coasts of Alabama and Northwest Florida in 1977 (click here to read this account). This record was later criticized and deemed by many to be a hybrid (here is where the Chicago bird is pointed out as support. Also, see p. 445 in Gulls of the Americas).
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| Presumed 4th cycle Western x Glaucous-winged specimen (CAS #1663). |
I can only try to imagine the wonderful experience Earl G. Wright and Edwin Komarek had when finding this bird in Lincoln Park in 1927; In their defense, the extent of hybridization between Westerns and Glaucous-wingeds was not understood in the early 20th century and very little had been published about this phenomenon. In Dwight's seminal work, "Gulls of the World" (issued by the AMNH in 1925), he makes no mention of this "hybrid problem" under either species' account. Birders and birding were introduced to these hybrids primarily through Hoffman et al. in the late 1970s (see The Auk, V95 N3).
Much thanks to the Chicago Academy of Science for housing this bird and allowing me to examine their collection. Also, due credit is in order to Bob Hughes who independently came to this same conclusion before my visit.
ALL PHOTOS ARE THE PROPERTY OF AMAR AYYASH AND MAY ONLY BE USED WITH PRIOR CONSENT.
