ious instinct_: by which we mean that the inherited nature of
the Curlew, as a tribe, is so constituted that, given the appropriate
internal conditions and adequate external stimulation, every individual
will respond in a similar manner--that is, the behaviour is primarily
determined by racial preparation. This is what we mean by the
_gregarious instinct_ biologically considered. We may resolve our own
experience in relation to the crowd into its simplest constituents,
project our own primitive feelings into the Curlew, and say that the
bird feels uneasiness in isolation and satisfaction in being one of the
flock. But in truth we know nothing, save by analogy, of the correlated
psychical state. All the knowledge we possess is derived from a study of
the objective aspect of the behaviour, which in simple terms may be
expressed thus: the individual is drawn towards its companions; there is
a relation between the size of the flock and the strength of the
attraction; and all Curlew behave similarly under similar circumstances.

This instinct controls the movements of many birds from early autumn to
the commencement of the breeding season. And so powerful is the control
that the individual is suppressed and its activities subordinated to the
welfare of the community as a whole. Flocks of Waders roam about the
tidal estuaries in search of food, and different kinds of Gulls assemble
there and preen their feathers or sleep; Warblers alter their mode of
life, and in the osier bed, or amongst the elders, seek their food
together in peace; Finches, Buntings, Pipits, and Wagtails, though food
is everywhere abundant, gather themselves together respectively into
bands which, as winter approaches, grow into flocks and even into
composite flocks; and as the Warblers leave for the south, so their
places are filled by flocks of Thrushes and Finches from the north. In
whatever direction we turn, when the days begin to shorten, it is the
community, not the individual, that thrusts itself upon our attention;
and throughout the winter continues to be the outstanding feature of
bird life.

With the approach of the breeding season we witness that remarkable
change which I have endeavoured to make clear in the previous
chapters--the disintegration of the flock and the reinstatement of the
individual. Instead of continuing with the flock, the individual now
goes forth to seek the appropriate breeding ground; and having arrived
there, is not onl