GREAT BLACK-BACKED GULL. 635 



bill very large and strong ; the irides straw-yellow, the edges 

 of the eyelids orange ; head, neck, tail, and entire underparts 

 pure white ; back, wing-coverts, scapularies, secondaries, and 

 tertials black with a tinge of dark slate, the feathers of the 

 three latter series ending in white ; primaries nearly black, 

 the first quill-feather white for the lower two and a half 

 inches ; the second for rather less, and barred with black on 

 the inner web ; all the others tipped with white, the upper 

 portions of the webs being lead-grey ; upper tail-coverts and 

 tail-feathers pure white — in less mature birds the white 

 of the outer primary is barred across, and the second is 

 white only at the extremity; legs and feet flesh-colour. In 

 winter the crown of the head and the occiput are slightly 

 streaked with ash-grey. The whole length of an adult male 

 is about thirty inches ; the wing, from the carpal joint to 

 the end of the longest quill-feather twenty inches. The 

 female measures twenty-seven inches, and her wing nineteen 

 inches. The bird from which the figure here inserted was 

 taken, was given to the Author by his friend Mr. Broderip, 

 and was shot at Putney during the frost which occurred 

 early in February, 1841. 



The young birds in their stages to maturity resemble the 

 young of the Lesser Black-backed and Herring Gulls, but 

 are always much larger, their legs are paler in colour, and 

 the light and dark markings of the plumage are more sharply 

 defined than in the Herring Gull, with which alone they can 

 possibly be confounded. The nestlings are so similar that 

 no distinguishing characters can be indicated. 



In the Gardens of the Zoological Society, the Great 

 Black-backed Gull has paired on several occasions with the 

 yellow-legged Herring Gull, but the eggs laid have not 

 proved fertile. 



