California Gulls in Colorado, This is such a great two part question and I only have a partial answer to it, and I admittedly mostly suck at gulls but...,
L.c. californicus, the nominate subspecies, breeds in central Colorado, southeastern Wyoming, and west to areas like Mono Lake, CA (Gulls of the Americas, Howell an Dunn, p. 396). The other subspecies, L.c. albertaensis, (slightly smaller and darker gray mantle, Stokes Guide to Birds of N.A.) breeds from the Great Slave Lake in the Northwest Territories, to eastern Alberta and Saskatchewan, south to southwestern Manitoba and northeastern North Dakota and "possibly has a more southerly winter distribution" (Gulls of the Americas) which could easily put albertaensis birds in CO in winter in my opinion, although the darker gray mantles in our winter birds are easily seen compared to Ring-bills and adult American Herring Gulls. Both subspecies move mainly to the west coast in the winter south to as far as to the Pacific side of the Isthmus in MX. Looking at specific photographs in the Gulls of the Americas book, even the authors write "presumed" blah blah subspecies name, although they say the coloration of albertaensis mantle can approach the mantle coloration of Ring-billed and Herring gulls. Howell and Dunn say to look at (photos best) P7 (count in from the outermost primary, p10) of the birds in flight, with L.c. albertaensis having "longer and whiter-tipped gray tongue" than our breeder, L.c. californicus. Having said this, I really don't see a big difference in the very close photos in their book, except maybe the gray tongue is slightly longer on P7 in the example on page 155. For sure, looking at photos of birds in flight, compared to ones I.D.'ed to known subspecies, might be the only way to go. Perched birds, at least for me, are just Cal Gulls. Just as interesting, Bob and Bob tell us that California Gull has expanded its range dramatically in the last half century. They, the Cal Gulls, not Bob and Bob, didn't start nesting at Antero Res until 1965, at Adobe Creek Res in 1988, and there were no CO winter records until 1960, and they were not regular in winter until the mid-1970s; hard to believe if you bird the larger CO reservoirs before freeze up in the past 10 years. If there are museum specimens from the last 10 years taken in the winter, this would help answer Amar's question much better. Bill Maynard Colorado Springs On Tue, 30 Nov 2010 04:07:24 -0800 (PST) Amar Ayyash <[email protected]> writes: > Hi everyone. I was recently in Colorado for the Ross's Gull and I > observed a flock of ~100 California Gulls at Cherry Creek. > > My question is two-part: > 1) What is the status of California Gull in Colorado? > 2) What is the expected subspecies, californicus or albertaensis, > and > does this change according to season? > > I've observed large assemblages of this species in California twice > this year, once in the winter and once in the summer. I must say, > the > Colorado birds showed greater variation in body size and primary > pattern and I was wondering if the Denver area is perhaps a contact > zone for both races. I do have photos and a video if anyone is > interested. > > Any information would be much appreciated. > > Thanks, > Amar Ayyash > Frankfort IL > > > > > > ____________________________________________________________ Obama Urges Homeowners to Refinance If you owe under $729k you probably qualify for Obama's Refi Program http://thirdpartyoffers.juno.com/TGL3141/4cf568024da3b4c722cst02duc -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
