Well, I have had a few replies, and the most common suggestion is that it is a first-year Herring Gull. It does look very much like one of the photos on allaboutbirds.org, so I have no reason to doubt that this is a pretty solid ID. I don't remember where I saw it, but I completely agree with the simplified Gull ID methodology that someone posted in a blog somewhere: "There are only two kinds of gulls, white guls and grey gulls." I guess this one is a grey gull ...
good birding - Jeff Parks , -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to cobirds+unsubscr...@googlegroups.com. To post to this group, send email to cobirds@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/d17a75f9-844d-490a-95ed-1167553e28db%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.