APRIL 89 



fresh localities. The fact that some species, such as 

 the Corncrake, appear to be dying out in certain 

 districts is evidence that there is not a general re- 

 distribution over the country each year. In general, 

 as is easily seen in the case of the Wheatear and 

 Yellow Wagtail, the males arrive first, as if to take 

 possession of the old home or seek a new one before 

 they are followed a few days later by their mates. If 

 we compare the migration, say of the Willow Wren, to a 

 wave breaking on our shores, its crest will represent the 

 main arrival, while a series of succeeding ripples will 

 stand for the smaller parties which continue to come 

 in for several days. When the wave is an unusually 

 strong one, it seems to carry individuals beyond the 

 ordinary range of the species. Thus it is only in 

 certain seasons that the Lesser Whitethroat reaches 

 Western Wales. The laggards, constituting the final 

 ripples of the wave, are probably birds which are going 

 much further north to nest. Thus long after our 

 resident Wheatears have settled down to breed, in 

 fact all through April and May, other wheatears may 

 be seen on passage. These we imagine to be on their 

 way to Iceland or Greenland, where the climate renders 

 it impossible for them to nest until a comparatively 

 late date. 



In an ordinary April we may expect to note some 

 twenty arrivals, the bulk of them naturally falling 

 within the last ten days of the month. It is the 



