CHAP. 11,] BIRDS. 19 



immediately connected with the process of reproduction. Some, 

 as the salmon, enter rivers ; others, as the herring and mackerel, 

 approach the coast in the breeding season ; but the exact course 

 of their migrations is unknown, and owing to our complete 

 ignorance of the area each species occupies in the ocean, and the 

 absence of such barriers and of such physical diversities as occur 

 on the land, they are of far less interest and less connected with 

 our present study than the movements of birds, to which we 

 shall now confine ourselves. 



Migrations of Birds. — In all the temperate parts of the globe 

 there are a considerable number of birds wliich reside only a 

 part of the year, regularly arriving and leaving at tolerably fixed 

 epochs. In our own country many northern birds visit us in 

 winter, such as the fieldfare, redwing, snow-bunting, turnstone, 

 and numerous ducks and waders ; ydt\\ a few, like the black red- 

 start, and (according to Eev. C. A. Johns) some of the woodcocks 

 from the south. In the summer a host of birds appear — the 

 cuckoo, the swifts and swallows, and numerous warblers, being 

 the most familiar, — which stay to build their nests and rear their 

 young, and tlien leave us again. These are true migrants ; but 

 a number of other birds visit us occasionallv, like the waxwinar, 

 the oriole, and the bee-eater, and can only be classed as 

 stragglers, which, perhaps from too rapid multiplication one year 

 and want of food the next, are driven to extend their ordinary 

 range of migTation to an unusual degree. We will now endeavour 

 to sketch the chief phenomena of migration in different 

 countries. 



Europe. — It is well ascertained that most of the birds that 

 spend their spring and summer in the temperate parts of Europe 

 pass the winter in ISTorth Africa and Western Asia. The winter 

 visitants, on the other hand, pass the summer in the extreme 

 north of Europe and Asia, many of them having been found to 

 breed in Lapland. The arrival of migratory birds from the 

 south is very constant as to date, seldom varying more than a 

 week or two, without any regard to the weather at the time ; 

 but the departure is less constant, and more dependent on the 

 weather. Thus the swallow always comes to us about the middle 



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