Posted by Phil Pickering (208.46.229.115) on April 18, 2001 at 21:13:53:
Reading my posts back, I think I probably should have elaborated briefly on the head shape, since I think this bird's is every bit as odd for Glaucous as the bill pattern. In my experience Glaucous, even the smallest presumed female barrovianus, tend to have the highest point on the head towards the rear of the crown, with the forehead peak shallowly angled, the rear peak more steeply angled, and the majority of the crown sloping forward (they seem most similar to Herring in this respect). Conversely, Glaucous-winged (seemingly both male and female) tend to have the highest point of the head more centralized, or even a bit forward, often have a bit of a high-domed look to the central crown or forehead, and most often have a shallowly angled peak to the rear crown. This is all more than a little subjective due to male/female differences and changes in appearance due to posture, but in this case the head shape seems so off for Glaucous that I think it goes beyond variability due to posture or sex.
I also didn't mean to imply that I definitely think this bird is almost all, or even mostly Glaucous, particularly since it actually seems closer to Glaucous-winged in body and head shape to me. I haven't seen anywhere near a large enough sample of presumed hybrids to know what features of either might be dominant traits, or do anything more than speculate about a percentage of purity.
Suppose I should shut up now.
Cheers,
Phil