Pianola AGU TU TBiO NA BeULEILiE TIN 27 
The main problem with gulls was with identification of Thayer’s Gull. 
The Committee is indebted to Messrs. R. Poulin and R.A. Foxall of Ottawa 
who suggested the approach used here for first year birds; it is the Com- 
mittee’s understanding that a comprehensive paper on this subject will be 
developed, and that the comparison chart is simply a summary of the 
characters being used at present in assessing reports of Thayer’s Gulls. 
We should note, however, that the plumages in this group of gulls 
approached a continuum, and great caution should be used in assigning 
birds to the less-common species. Bill colour is one area of doubt: the 
Ottawa immature birds have all had dark bills (R.A. Foxall, pers. comm.), but 
that of one thayeri immature in the Royal Ontario Museum has a pale base, 
probably the source of Snyder’s statement on this species. Another caution 
is that most of the literature reviews and all the specimens in the Royal 
Museum treat thayeri as Larus argentatus thayeri. The discussion here 
assumed that birds named to this race correspond to Larus thayeri as 
presently designated. 
11 Westbank Crescent 
Weston, Ontario 
M9P 154 
Northern 
Area 
Fall 
Campout 
Photo by Peter Dring 
