444 INTRODUCTION TO NATURALISTS CALENDAR. 



migratory period, and are, probably, supplied both from abroad 

 and from the more exposed districts of this country. Many of the 

 hawks disappear altogether during spring and summer, seeking the 

 wilder and more unfrequented grounds to breed and rear their 

 young. They reappear again 'in their usual haunts about the 

 middle or end of September. Along our shores and sea marshes 

 vast numbers of the plovers, sandpipers, curlews, &c., spend the 

 winter, many of which have merely returned with their young from 

 a more inland breeding resort. The numerous congregations of 

 the young, in autumn, assembling in large flocks together, show 

 another kind of migration, being very marked in the black and 

 white wagtail, chaffinch, titmice, lapwing, and other plovers. &c. 

 A few species, again, which spend the whole season of incubation 

 in other parts, are seen once or twice yearly for a short period only. 

 The short-eared owl, which in some parts of England is met with 

 regularly about the commencement of the winter migratory period, 

 is in great part only on return from the more northern parts of this 

 country, where it is known to breed. The ring-ousel breeds in the 

 alpine districts of England and Scotland, but it is only seen upon 

 the English downs, and so often recorded by White, and among 

 the mountain ash and cottage gardens in Scotland only for a few 

 days, in going and returning to and from their breeding quarters. So 

 it is with the common dotterel upon our lower moors, and large 

 numbers of our sandpipers, &c , are also only seen for a day or 

 two, in similar circumstances. 



The periodical change of colour in the plumage of birds is often 

 very marked ; it is incidental in great measure to the season of 

 incubation, previous to which it gradually approaches completion ; 

 and, as that important time arrives, it, along with the voice, obtains 

 its fullest vigour, clearness and brilliancy, and the latter sometimes 

 puts on changes of great contrast with the full and usually chaste 

 winter garb. These changes are most characteristic and distinct 

 in the waders, water fowl, and gallinaceous birds, and among these 

 are almost general ; in other families, although a greater brilliancy 

 always occurs, it is only in some that the changes are very marked. 

 In some species these changes take place by a loss of some parts 

 of a feather, thereby bringing into view some other portion, and 

 so producing a different tint ; in others, the colour of the feather 

 entirely changes. These variations take place more or less rapidly 

 with the seasons ; but in some instances, the change is effected in 

 a day or two, as in many of the plovers and sandpipers, some 



