MIGRATION i6i 



to the Shetlands ; in most years the autumn tide from the 

 Continent sets in much less noticeably. 



(B) In a North Temperate country like Britain the 

 birds may be grouped, from the migration point of view, in 

 five sets : — 



(i) There are the Summer Visitors, e.g. swallow, swift, 

 cuckoo, nightingale, mostly insectivorous, which arrive 

 from the south in spring, nest and breed within our bounds, 

 and return southwards and south-eastwards in late summer 

 or autumn. 



(2) There are Winter Visitors, e.g. fieldfare, redwing, 

 snow bunting, many northern ducks and divers, that come 

 southwards and south-westwards to our shores in winter, 

 and return northwards in spring to their breeding-quarters. 



(3) In a set by themselves may be ranked the birds- of- 

 passage in the narrow sense, e.g. the great snipe, the little 

 stint, and some of the sandpipers, which rest on our shores, 

 for a short time only, on their way farther south or farther 

 north. 



(4) There are many " partial migrants," e.g. lapwing 

 and goldfinch, which are always represented in the country 

 in question, but not always by the same individuals. Some 

 leave the country, others do not. Those of a particular 

 locality move southwards in autumn, and their place is 

 taken by a wave from farther north. 



(5) There remain the strictly resident birds, such as in 

 Britain the red grouse, the house sparrow, the rook, and 

 the robin. 



Perhaps another division should be made for " casual 

 vagrants " or stragglers which occasionally appear far off 

 their normal range, e.g. the American Kildeer plover in 

 Aberdeenshire in 1867 or the Glossy Ibis in the same 

 region in 1920. 



(C) Birds breed in the colder area of their migratory 

 range. Part of the reason is, no doubt, that the brooding 

 birds and the nestlings are apt to suffer from the heat of 

 the sun. Thus the general movement in autumn is south- 

 wards, or south-eastwards, or first westwards and then 



M 



