248 THE MIGRATION OF BRITISH BIRDS 



of coasting migrants — individuals that merely pass us 

 from winter quarters in lower latitudes. 



This coasting migration begins apparently as soon 

 as the migration which is exclusively of a departure 

 character, but is weak until March, and perhaps attains 

 its greatest strength in April and May. It is impossible 

 to distinguish with certainty between coasting migrants 

 and migrants that have passed the winter with us, or in 

 the case of species that breed in our area ; but with 

 those species — high boreal forms, as a rule — that neither 

 winter nor breed with us, there is no difficulty, and these 

 birds generally coast us late in spring. The Whimbrel, 

 for instance, passes us very regularly towards the end of 

 April, but the migration of this species is most marked 

 in May, dying down in June. The Ringed Plover begins 

 to pass our coasts in March, very sparingly, the great 

 flights crossing us in April, and lesser numbers again in 

 May. The Sanderling passes us pretty regularly through- 

 out April and May, a few in June ; the Skuas of various 

 species coast us chiefly in April. The Little Stint passes 

 our coasts sparingly in April, but in greater numbers 

 (although even then by no means dominantly) during 

 May ; as also does the Knot, which perceptibly prolongs 

 its passage into June. The Curlew Sandpiper, never 

 very common with us, coasts us in April, ]\Iay, and 

 June. 



Owing entirely to the fact that all or nearly all this 

 early spring migration is entirely among species that 

 breed or winter in the British Islands, no season-flight 

 is very apparent until the species that visit us exclusively 

 in spring to breed in our area begin to make their 

 appearance. While all this other migration which we 



