250 THE HAUNTS OF LIFE 
of the body, to one side or the other, bending 
and straightening, may be very effective al- 
though there is no actual movement of the 
legs. Experienced mountain-climbers are also 
aware of the importance of slight adjustments 
which are eventually made almost without 
thinking. In any case we are probably safe 
in saying that the sailing albatross is not be- 
having like a kite. 
MIGRATION THE CLIMAX 
The crowning advantage of the power of 
flight in birds was that it enabled them to mi- 
grate, to evade the difficulties of the winter. In 
north temperate countries the great majority 
of the birds show this seasonal mass-movement 
between a nesting-place and a resting-place, 
the former being always in the colder part of 
the range. It is remarkable in many ways, this 
migration of birds (see our JV onder of Life 
(1914) and Biology of the Seasons (1911)); 
it occurs in such a punctual, orderly way; it 
is such an intense activity, for many migrants 
seem to keep up for hours on end a speed of a 
mile a minute; it means such an annihilation 
of distance, for the Pacific Golden Plovers of 
