h
amazement on account of the magnitude of the distance traversed or the
nature of the difficulties overcome. For, after all, what does each
individual seek? There may be some immature birds which, though they
have not reached the necessary stage of development, happen to fall in
with others in whom the impulse is strong and are led by them--they know
not where. But the majority seek neither continent nor country, neither
district nor locality is their aim, but a place wherein the rearing of
offspring can be safely accomplished; and the search for this place is
the earliest visible manifestation in many species of the reawakening of
the sexual instinct.

The movements of each individual are then directed towards a similar
goal, namely, the occupation of a definite station; and this involves
for many species a distinct change in the routine of behaviour to which
previously they had been accustomed. Observe, for example, one of the
numerous flocks of Finches that roam about the fields throughout the
winter. Though it may be composed of large numbers of individuals of
different kinds, yet the various units form an amicable society actuated
by one motive--the procuring of food. And since it is to the advantage
of all that the individual should be subordinated to the welfare of the
community as a whole there is no dissension, apart from an occasional
quarrel here and there.

In response, however, to some internal organic change, which occurs
early in the season, individuality emerges as a factor in the developing
situation, and one by one the males betake themselves to secluded
positions, where each one, occupying a limited area, isolates itself
from companions. Thereafter we no longer find that certain fields are
tenanted by flocks of greater or less dimensions, while acres of land
are uninhabited, but we observe that the hedgerows and thickets are
divided up into so many territories, each one of which contains its
owner. This procedure, with of course varying detail, is typical of that
of many species that breed in Western Europe. And since such a radical
departure from the normal routine of behaviour could scarcely appear
generation after generation in so many widely divergent forms, and still
be so uniform in occurrence each returning season, if it were not
founded upon some congenital basis, it is probable that the journey,
whether it be the extensive one of the Warbler or the short one of the
Reed-Bunting, is underta