BIRDS OF ESSEX COUNTY. 97 



Although not as shy as the Great Black-backed Gull, the Herring Gull along 

 our shore rarely forgets himself to the extent of approaching within gunshot, 

 ex'cept in the populous harbors where he appears to know that he is safe from 

 persecution. Mr. W. A. Jeffries tells me that at Swampscott Beach where the 

 Gulls are not molested, he has walked within twenty-five feet of a flock of these 

 birds. 



The varied plumage of the Herring Gull is always an interesting study, and 

 it is superficially evident from the large number of dark and mottled birds at all 

 seasons, that it takes several years to attain the beautiful adult plumage. What 

 appears to be a dark tip to the tail, so prominent in young birds of a certain age, 

 is often retained after increasing whiteness has set the stamp of years, but it is 

 entirely absent in the snowy white tail of the fully matured bird. Birds with 

 pure white tails with the exception of a slight central sprinkling of dusky brown 

 and with a few faint gray streaks in the upper breast, are not uncommon. 

 These, unless examined carefully with a glass, or in the hand, would easily pass 

 for full adults. 



Astley,! who has kept Heiring Gulls in captivity, says that although they 

 attain a nearly complete adult plumage at the third autumnal moult, the bright 

 yellow bill is not assumed until the fourth year. I have been puzzled by seeing 

 birds with yellow bills whose plumage still showed considerable immaturity, 

 Dwight 2 states that the bill becomes yellow when the second nuptial plumage is 

 assumed. There must, it seems to me, be great variation in the rate at which 

 the birds attain maturity. 



I was interested to note at Great Duck Island, off Mt. Desert, Maine, on 

 June 17th, 1904, that while the great majority of the Herring Gulls that breed 

 there were in full adult plumage, those with dark wings and black tips to the tails 

 were not uncommon, while a few birds were to be seen with a considerable scat- 

 tering of gi-ay on the breast and upper belly ; none darker than this were to be 

 seen. These birds at a distance would appear white except for their dark tails 

 and wings. 



The recognition of the Herring Gull in the field is not always simple. 

 Most of our Gulls differ from each other chiefly in size, many, especially when 

 in immature plumage, being othenvise told apart with difficulty. The Great 

 Black-backed Gull in full adult plumage is easily recognized if seen from above, 

 by his black back and wings, the latter with a narrow white border, but it must 

 always be remembered that in certain lights Herring Gulls also look black 

 above. Seen from below as the birds fly over, the differences are slight ; but a 

 dark edge can often be seen on the wing of the Great Black-backed Gull. The 



' H. D. Astley : My Birds in Freedom and Captivity, p. 160, 1901. 

 2 Jno. Dwight, Jr. : Auk, vol. 18, pp. 49-63, 1901. 



