On February 3 Rick Blom wrote: >>> Rick Blom <rblom@blazie.com> 02/03/98 08:23am >>> On Feb 2, Howard Elitzak wrote: >This message is in reference to Gene Scarpulla's Conowingo Dam >report. > >You indicated you observed "1 fourth winter" and "2 adult" LBBG's. Did >you perhaps intend to report a third winter bird? If not, what is the >difference between a fourth winter and adult LBBG? I was under the >impression that this was a four-year gull. Lesser is a four-year gull, as is Herring. There are, however, individuals that seem to be in fourth-winter plumage, based on retained subadult characters. These are birds that appear to be full adults in almost every respect and are certainly not third-winter. Typically they have some dark on the bill. Sometimes they also have duller yellow legs, reduced head streaking (usually heavier in adults), smaller white mirrors in the primaries, and sometimes a slightly darker eye. The key is the bill. It has long been assumed that these birds are in their first full adult plumage (which happens in fourth winter) but have retained a few indications of third summer plumage, which will presumably be lost in the spring. If they are like Herring Gulls, a few will retain some indication of subadult plumage right into their fifth winter. They may also retain a few subadult brown feathers in the body plumage, but that is very hard to see on Lessers as opposed to Herrigns because the back is so dark. It is not certain that these birds are in fourth-winter plumage of course. It is based on assumptions about molt and the tendency of some birds to be a little slow when it comes to changing soft part colors. We have been using "fourth-winter" to designate them for more than a decade and perhaps it should be considered an indication of a particular plumage pattern (which is not that rare) rather than a precise age category. Rick "Everywhere I go I'm asked if the university stifles writers. My opinion is that they don't stifle enough of them. There's many a bestseller that could have been prevented by a good teacher." Flannery O'Connor Rick Blom rblom@blazie.com Bel Air, Maryland Rick-- Many thanks for your comprehensive response. Your "fourth winter" classification offers a nice solution to the ambiguous "third year/adult" by allowing one to infer that the bird is in fact much closer to full adult plumage. My compliments!