THE SEA-FLIERS. 



177 



variety of creatures met with in the sea, their prey being always taken when on the wing. These birds 

 are strictly monogamous : a few weeks before the commencement of the breeding season they begin to 

 assemble in the vicinity of their meeting-place, returning year after year to the same locality. Such 

 species as inhabit the sea-shore generally select coral-banks, islands, or long spits of bare sand for this 

 purpose, while such as settle inland seek out similar, but less barren spots, in the vicinity of swamps 

 and marshes, the various species usually breeding apart from each other. Such as resort to morasses 

 lay their eggs in a mere depression of the ground. Their unpretending apologies for a nest are 

 sometimes isolated, sometimes so crowded together as literally to cover the ground so thickly, that the 



THE CASPIAN TERN (Sylochdidon Caspia). 



brooding birds have all to sit with their heads in one direction, and a man cannot pass between them 

 without crushing the eggs of contiguous nests. Even such species as resort to trees construct nothing 

 in the shape of a nest, but deposit their eggs in chinks of the bark or inequalities of the branches. 

 Most of the Terns lay three eggs, others two, whilst those that breed on trees deposit but one. The 

 male and female brood alternately ; during the heat of the day, however, they leave their eggs to be 

 kept warm by the sun. The young are hatched in about a fortnight or three weeks, and make their 

 appearance clad in down ; they leave the hollow that has served as a nest on the day of their birdi, and 

 run at once down to the water's edge, quite as fast as their parents, by whom they are anxiously and 

 carefully tended. 



The RAPACIOUS TERNS {Sykchelidon) are the largest of the Sea Swallows, and distinguishable 



VOL. IV. 141 



