316 INTRODUCTION TO NATUHALIST's CALENDAU, 
to be observed and registered ; and accompanying the number, there is 
a duplicate copy, printed on thin paper and with printed address, 
which it is requested may be filled up and posted in the first week 
of January, 1850, when, if health and circumstances permit, a summary 
of the registers and observations returned will be drawn up and printed 
with an early succeeding number. 
For the better filling up of these tables, the following observations 
may not be inappropriate : — ■ 
The tables and lists of species have been drawn up, as far as possible, 
to suit any locality ; at the same time, many omissions may have been 
made, which experience in a future year may remedy, and there may 
be many things inserted which are not applicable, and may appear 
useless in certain districts. Thus, the return filled up in Orkney, will 
produce a very different appearance from one made in the middle or 
southern districts of England. 
In these returns, it will be very desirable to know the elevation above 
the sea as nearly as possible ; to have a general register of the tempera- 
ture and weather, with a short description of the character of the 
country and its vegetation around the localities where the observations 
are made. In the curious and interesting subject of migration, particular 
attention is desired. The average temperature at the times of appear- 
ance and departure ; the direction of the wind ; the general character 
of the weather ; the condition and progress of vegetation, should all 
be observed. It might be supposed, that the arrival of the migratory 
species in other countries would be influenced more by the climate of 
that from which they departed than of that to which they came ; that 
an earlier frost, or mild weather, would have the effect of driving them 
away or inducing them to prolong their departure ; in this country, how- 
ever, though a cold autumn has an evident effect on the time of the depar- 
ture 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 veo^etation in this countrv does make a differ- 
ence in the time of appearance of several species, particularly the Sylviadce ; 
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 8ylviad(B 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 ISTovember, 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. 
