INTRODUCTION TO NATURALISTS CALENDAR. 443 



departure of the swallows, and many of our summer birds, a mild 

 spring does not always hasten the departure of the winter visitants. 

 The arrival of some summer birds, as the wheatear, does not 

 seem at all influenced by the mildness or continued severity of the 

 spring here ; but we have observed that mildness and advance of 

 vegetation in this country does make a difference in the time of 

 appearance of several species, particularly the Sylviadce j and it 

 may be asked whether the progression of these and others from 

 Southern Europe and Africa is gradual, advancing with the seasons ? 

 The laws which regulate the migratory zone of some species are 

 not, probably, applicable to such as appear to start at once and fly 

 to their destination. The great mass of swallows depart from this 

 country at once, but the appearance of their numbers is somewhat 

 more gradual. The Sylviadce appear gradually. The migratory 

 thrushes, again, come and depart at once. So also do the snipes, 

 woodcocks, and others of the Scolopacidce. If resident on or near 

 the sea-coast, attention should be paid to the ornithology after 

 remarkable storms, particularly during March and April, October 

 and November, and both on the coast and inland during these 

 months, when migration takes place, and the young are leaving 

 their breeding places and congregating, many rare species have 

 been met with, driven out of their ordinary tract ; and vast flocks 

 of species generally few in number, sometimes in the same way 

 appear, showing the influence climate or the seasons may have in 

 the distribution of animal life. On the coast, it is also curious to 

 mark the habits of the different sea-fowl previous to, or after the 

 occurrence of a storm, or any marked change in the weather. 



Independent of regular migration, by which we mean the arrival 

 of some birds (not at other seasons found in our islands) in spring, 

 for the purpose of incubation, and then remaining with us during 

 the summer months ; or the arrival of some birds in late autumn 

 from another county, and remaining during the winter months, 

 apparently to enjoy a larger supply of food and a milder climate, 

 not afforded by their more northern summer quarters ; there are 

 large accessions made to the numbers of some permanently 

 resident birds, either altogether from another country, or by a 

 partial migration from one locality to another temporarily more 

 suitable. In many districts a large addition is received in autumn 

 to the stock of our common thrush and blackbird. So is there 

 also of the common snipe, in many places where it breeds and 

 is permanently resident. They arrive before or about the usual 



