A FIRST GLANCE AT THE BIRDS 



of the largest gulls, with a comparatively slender bill, black 

 primaries and a pale blue mantle. Even the immature bird 

 of this species may be distinguished by its paler shade of 

 brownish gray and its more slender bill. 



The gulls belonging to the medium-sized class are the most 

 difficult to differentiate. They are the California, the mew, 

 the short-billed and the ring-billed gulls. Of these the Cali- 

 fornia gull is probably the most abundant species. It is of 

 about the same size as the ring-billed, but is a shade darker 

 in color. The ring-billed gull may generally be known by 

 the ring of black encircling its beak, and the mew and short- 

 billed may be told from the rest by their smaller size and much 

 shorter beaks. There is, however, no characteristic by which 

 the short-billed may be distinguished from the mew gull as 

 they are seen in flight. 



The third group of gulls includes but one species, the beau- 

 tiful Bonaparte's gull, a dainty, graceful little creature, with 

 typical pearl-blue mantle, and, unlike the other gulls of this 

 region, adorned with a hood of dark-slaty color. 



The terns, which also frequent our coast, are similar to the 

 gulls in form and color but even more slender than Bonaparte's 

 gull. The swallows among sea birds, with long, forked tails, 

 sharp wings, and acute bills, they may always be distinguished 

 by their habit of flying with the head pointed abruptly down- 

 ward, and by their practice of plunging from the air down into 

 the water — a habit never shared by the gulls. 



The confines of San Francisco Bay are too limited to hold 

 such ocean rangers as the albatrosses and petrels, which form 

 the next great division, known as the tube-nosed swimmers. 

 Three groups are included in this order — the albatrosses (the 



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