98 MEMOIRS OF THE NUTTALL ORNITHOLOGICAL CLUB. 



immature birds of the latter species although closely resembling in plumage 

 immature Herring Gulls, are more streaked and buffy, less slaty gray. It is 

 impossible to judge of size unless we have something for comparison. On land 

 we are able to judge of the size of a bird by comparison with known objects, 

 like leaves of trees, flowers, fence posts, etc., and the intervening objects make 

 us good judges of distance. On the sea or on a sand beach, in the absence of 

 these objects, distances are deceptive, and we can only judge of size by direct 

 comparison with other birds. Side by side. Herring Gulls appear somewhat 

 smaller than Great Black-backs, but with either alone it is unwise to judge of 

 the size. By their habits on the wing they cannot be distinguished as both 

 may be equally sluggish, or equally light and graceful. 



Next in size, smaller than a Herring Gull, is the Ring-billed Gull, which 

 except by direct comparison, appears both in plumage and in flight very much 

 like the Herring Gull. The young birds are, however, never quite as dark. 

 When the birds are side by side the Herring Gull is seen to be considerably the 

 laro-er of the two, but alone it is very easy to mistake one for the other. The 

 fact that the Ring-billed Gull is generally less shy is a point that has often 

 helped me and the ring-marking on the bill can sometimes be made out. Only 

 slightly smaller than the latter bird is the Kittiwake, often confused with the 

 Herring Gull, but generally more active and graceful, and with a slight difference 

 in the wing-tip markings, while from the smallest of all our common Gulls, the 

 Bonaparte's Gull, there is generally no difficulty in the differentiation. It is to 

 be remembered that the black band at the tip of the tail is common to all the 

 Gulls in certain stages of immature plumage. In the Ring-billed, Kittiwake, 

 and Bonaparte's Gulls this is a true band on the long tail feathers, but the effect 

 is the same in the Herring and the Great Black-backed Gulls, although when 

 the birds are examined carefully with a glass or in the hand, it is seen in them 

 to be due to the fact that the long upper and lower coverts, which are light in 

 color, cover the dark bases of the large tail feathers. The band therefore is 

 broader and less sharply defined. 



19 [54] Larus delawarensis Ord. 

 Ring-billed Gull. 



Not uncommon transient visitor ; (winter .?) ; spring ; July 17 to October 30. 



I can give no spring dates but Mr. Outram Bangs writes me as follows : " I 

 distinctly remember seeing Larus delaivareusis several times in the spring ; once 

 in Gloucester Harbor I saw a lot of them. They were tame and I saw them 



