COMMON, HERRING, AND BLACKBACKED-GULLS 155 



THE COMMON, HERRING, AND BLACKBACKED- 

 GULLS 



[F. B. KIRKMAN] 



The four gulls that form the subject of this chapter provide a 

 convenient group for purposes of comparison. The comparison cannot 

 at present be complete, for our knowledge of the domestic details of 

 their lives is defective. But the purpose of this book is still served, if 

 we show what has to be found out as well as what has been found out, 

 and so clear the way for future work. 



In point of size and coloration the greater blackbacked-gull is to 

 the lesser blackbacked as the herring-gull is to the common. The 

 first two measure in length about 29 and 22 inches, the second two 

 24 and 18 inches respectively. The first two have blackish or slate- 

 coloured backs and wings, the other two grey. In adult plumage the 

 larger of the first two, the great blackbacked, has flesh-coloured legs, 

 so has the larger of the second two, the herring-gull. The smaller 

 species in both cases have yellowish legs. The common-gull alone of 

 the four lacks the red blotch on the downward projecting angle of the 

 lower mandible. The young of all four species have a curious mottled 

 plumage, of which the dominant colour is brown, and it is only after 

 three to five years of gradual transformation that they assume the 

 complete garb of maturity. Except in size and shape, they look 

 entirely different from the adults, and no doubt illustrate a phase 

 in the evolution of the species from the ancestral plover-like form. 



The distribution of the species in the British Isles presents many 

 points of interest. Why, for instance, does the common-gull limit its 

 breeding-range to Scotland and the west of Ireland ? There are 

 many suitable places in England and Wales. Why, again, is the 

 herring-gull the most widely distributed, not only in but outside the 



