ORNITHOLOGICAL NOTES FROM A SOUTH LONDON SUBURB. 
MI GR ATT ON. INGO TEs. 
A FEW FACTS AND THEORIES CONCERNING ‘THIS 
WONDERFUL MOVEMENT. 
The migratory impulse in birds is so remarkable a habit 
that it has always been of extreme interest to the Naturalist, 
and consequently various speculations have been mooted as 
to the object of the movement, and also as to the “line” or 
direction taken by the migrants. 
OBJECT. 
So far as the object is concerned, the necessity for food 
and an equable temperature would supply sufficient reasons 
for a change of locality in the case of both summer and winter 
visitors. 
So TETONTE o> 
The line or direction taken in spring and autumn by the 
various visitors 1s not always easily followed, for reasons given 
later, although the gezera/Z direction will be demonstrated. 
The remarks that follow are founded on more than 40 years’ 
observation of the arrival and departure of migrants to and 
from our shores; during which time a careful record has been 
kept of the direction taken by the birds, and of the prevailing 
wind at the time of passage. As a result of these observa- 
tions, it would appear that this passage is not, as might be 
supposed, an invariable, exact, and simple movement from 
north to south in autumn and vice versa in spring, in the case 
of the summer visitors; nor to the east in spring and to the 
west in autumn with those that spend winter with us. Such 
a statement would, nevertheless, roughly indicate the line the 
migrants take. 
56 
