LIFE HISTORIES OE NORTH AMERICAN GULLS AND TERNS. 57 



plumage. The white heads and bodies are much obscured with smoky gray. 

 An extreme is represented by birds absolutely pure white, the "hutchimii" 

 type. The dark bill of the young bird is replaced by a bill which is partially 

 yellow. A partial prenuptial moult occurs in April, producing the second 

 nuptial plumage, in which some birds, except for wings and tail, are now like 

 adults. 



The adult winter plumage is acquired by a complete postnuptial 

 molt, in August and September, when the bird is 26 or 27 months 

 old. This plumage is characterized by the pure white head and body 

 plumage, pale pearl-gray mantle and wings of the same shade, fad- 

 ing to white at the tips of the remiges. A few birds still retain 

 traces of immaturity, such as an occasional mottled feather or some 

 signs of dusky clouding on the head, which disappear at the third 

 partial prenuptial molt. In the complete, postnuptial molt the 

 remiges are shed in pairs, in regular rotation, beginning with the 

 inner secondary and ending with the outer primary. 



Food. — The glaucous gull is noted for its ravenous appetite, for 

 it is a voracious feeder and is not at all particular about its diet, 

 which includes almost any kind of animal food whether fresh or 

 carrion. Its fresh food consists of fish or mollusks, which are usually 

 stolen from other sea birds, starfish, sea-urchins, surface-swimming 

 amphipods and crustaceans, and the eggs and young of other sea 

 birds. Yarrell (1871) says that "it feeds also on Cancer pulex and 

 araneus; extracts the soft animals from the shells of Venus islandica, 

 Pecten islandicus, and searches closely for the lump-sucking fish, 

 Gyclopterus lumpus." That it is not content with devouring the 

 eggs and young of dovekies, murres, and other small sea birds is 

 shown by the much quoted statement by Swainson and Richardson 

 (1831) that " one specimen killed on Captain Ross's expedition, dis- 

 gorged an auk when it was struck, and proved by dissection to have 

 another in its stomach." As a consumer of carrion it is undoubtedly 

 useful ; it feeds freely on dead fish or other animal refuse, which it 

 finds along the shore, the entrails of fish, which are thrown over- 

 board, the carcases of seals and the remains of animals or birds 

 killed by hunters. Murdoch (1885) says: 



If a duck be shot so that he fall in the water or any not easily accessible 

 place, an hour is generally time enough for him to be reduced to a skeleton by 

 the gulls. 



Nuttall (1834) states that they " are said to attend on the walrus to 

 feed on its excrement"; also that when "pressed by hunger," they 

 sometimes even condescend to share the crow berry with the ptarmi- 

 gan. Hagerup (1891) observes that "after the young leave their 

 nests in August they gather on the flat tracts along the shore and feed 

 on the berries of Empetrum, nigrum, of which they consume a vast 

 quantity." 



