behind it, sees at one moment the right eye
and at another the left. No movement of the
feet or of the legs is perceptible, and the shifting
of the body continues whether the eyes are
open or closed. This body movement enables
the bird to survey a much larger area of ground
than it would otherwise be capable of doing,
and thus adds to its security. As far as my
experience goes, the movement is less evident
amongst the members of a flock than when
an individual is resting, alone, or even with a
few companions, which may be due to the fact
that since some members are always awake
and watchful, a bird of prey would have more
difficulty in approaching a flock unawares than
it would have in approaching a single individual.
With the greatest ease a Sparrow-Hawk can
pick up a Thrush as it feeds on the meadow
by itself, but if it attempts to seize one of a
flock, the chances are that its approach is
signalled and that its prey escapes. And not
only do the different members give warning
one to another of the approach of danger,
but they also combine to harass or even to
drive away an enemy. So that there can be
no doubt that the gregarious instinct is service-
able in promoting the welfare of the race, and
has, as its end, the preservation of the individual
in order that it may take its share at the
appropriate time in procreating its kind.
In winter, then, the individual loses its individuality and is subordinated to the welfare of the community, whilst in spring it regains
