MIGRATION: ON THE |€CQAST. 283 
the present volume are migratory, although the 
seasonal movements of many of the species cannot 
be remarked, to any great extent, by the wanderer 
along the coast. Such thoroughly aquatic species 
as the Auks, the Petrels, the Divers, and the 
Grebes, move south or north, according to season, 
some distance from the land; and it is often only by 
the chance of rough weather driving these birds 
near to the land, that we are enabled to learn that 
their migrations are in progress, or that certain 
species have once more returned to our area for 
their winter or summer sojourn therein. The 
Ducks, Geese, and Swans, are birds of migratory 
habits, and in certain localities much of their 
seasonal movements may be observed from the 
shore. Then, again, the Gulls and Terns, although 
often migrating some distance from the land, may 
not unfrequently be seen passing up or down the 
coast on passage. This is especially the case with 
the Black-headed Gull, and the various species of 
Terns. These latter birds are often seen, in spring 
and autumn, in flocks of varying size, flying north 
or south, close inshore, fishing as they go, some- 
times remaining a day here or there, where food 
chances to be plentiful. The migrations of certain 
species of land birds that reside in littoral districts 
are also pronounced and regular, and easily re- 
marked along the coast ; the arrival and departure 
of Martins and Swallows being a specially interest- 
ing feature. But the most remarkable birds of all, 
