INTRODUCTION TO NATURALIST’S 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 Sy/vzade@,; 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 Sy/viade appear gradually. The migratory 
thrushes, again, come and depart at once. So also do the snipes, 
woodcocks, and others of the Scolopacide. 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 fourd 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 
