GODWITS, SANDPIPERS, AND PLOVERS 405 



first, in others the young — both separately ; while of 

 certain species the adults never come at all, though the 

 young - are abundant. That is to say, these birds only 

 once in their lives travel by this route ; in after-years they 

 seek another. A single principle stands out clear — that 

 old and young never travel together. The causes that 

 actuate these discrepancies are too wide- a subject for 

 discussions within a chapter — even were they within my 

 power to define ; but one general rule may be incidentally 

 noted, namely, that in proportion as a species is dependent 

 for food on fresh water and its productions, so must its 

 members hurry forwards and southwards in autumn. 



One other point is noteworthy. While most of our 

 winter waders leave us in March, still retaining their 

 winter-dress, yet a month or six weeks later, in May, 

 another lot, including many of the same species, pass 

 along the coast, these having acquired more or less of 

 their summer-plumage. It is interesting also to observe 

 that in the remote Taimyr Peninsula, Dr Walter cate- 

 gorically remarks, that in each case, he had noticed 

 immature birds in flocks at the same time and place that 

 the adults were incubating. Where immaturity spends 

 its summer is an ever recurrent problem. 



Oystercatcher. — On January 20th, 1882, observing a 

 single bird swimming far out in deep water, and expecting 

 it was a "pensioner" or wounded goose (which always 

 separate from the packs and are found singly thus), we 

 "paddled" out. To our surprise, the bird proved to be 

 an oystercatcher, which, after rising close to the boat, 

 flew round and again settled in the deep. Except on this 

 occasion, I never saw a wader swim of its own accord ; 

 though, when winded, many of them can swim, and even 

 dive, fairly well. 



