440 GULLS. 



approach. It is of very voracious appetite, and preys upon all kinds of animal 

 substances that may happen to be cast ashore. It also keeps close watch 

 upon the lesser gulls, whom it drives from any food they have discovered, 

 appropriating the whole to itself: it will even sever and devour the fish from 

 the hooks of the tishermen, if left dry by the ebbing of the tide. Its flight is 

 slow, but light, without much exertion of its pinions, and, as in other species 

 of the genus, always opposed to the wind. Its voice is a strong and hoarse 

 cackle, that may be heard at a great distance when the bird is saihng in the 

 air; but this is more frequently repeated during the spring and breeding season 

 than at any other times. 



On the water, this gull is extremely light, swimming with little exertion, 

 gracefully rising and falling with the undulating waves of the ocean: it is 

 capable of sustaining a long and continued flight, and while constantly wan- 

 dering over the surface of the water, or searching along the coast with every 

 rising and receding tide, it seldom fails to fmd a plentiful supply of materials 

 for the gratification of its omnivorous appetite. 



The black-backed gulls build their nests on inaccessible rocks, or sometimes 

 in marshes near the sea, reserving the place selected entirely to themselves, 

 and not even permitting birds of their own species to intrude upon their privacy ; 

 nevertheless, they are not always suffered to go unmolested, seeing that their 

 eggs are regarded as dainties, being thought to resemble those of the plover. 



Sub-Family IL 

 THE SKIMMERS. RHYNCHOPSIN^.* 



(IicxERiAL Characteristics. — Mandibles unequal, the upper one always shorter than 

 the lower, which is only received in a narrow groove, their sides suddenly much 

 compressed from the base ; the wings lengthened, acute, and curved at the tip ; the 

 tail moderate and forked ; the tarsi rather longer than the middle toe, and covered 

 with transverse scales; the toes moderate, and the anterior partly united by an 

 indented web. 



The Skimmers differ from the true gulls in the form of their 

 bill, which is so remarkable as to distinguish them at once from 

 all other birds. Their beak is elongated and compressed, so as 

 almost to resemble the blades of a pair of scissors placed one 

 above the other. The upper mandible is considerably shorter 

 than the lower one, which consequently projects to some distance 

 beyond it. The wings are long and pointed, indicating great 

 power of flight, and the tail is forked. These birds are peculiar 

 to the tropical parts of both hemispheres. They prefer the shel- 

 tered inlets and estuaries of rivers, over the smooth water of which 



/iiJj'Xos, rhynchos, a beak; d>^, ops, the face: beak-faced. 



