f different pairs, we shall find that pairing is seldom followed
by an immediate attempt to build; that an interval of inactivity is the
rule rather than the exception, and that this interval varies in
different species, in different individuals, and in different seasons.
Our imaginary male and female will therefore be faced with considerable
difficulty; for with nothing in the external environment to attract them
and with no restriction imposed upon the direction or extent of their
flight, their union will continue to be, as it began by being,
fortuitous. Next, let us consider their position were a disposition to
establish a territory to form part of the inherited nature of the male.
Each one will then be free to seek food when and where it wills and to
associate with other individuals without the risk of permanent
separation from its mate; and, no matter how long an interval may elapse
between mating and nest-building, each one will be in a position to find
the other when the appropriate moment for doing so arrives. Hence, while
preserving freedom of movement for each individual, the territory will
render their future, as a pair, secure.

No doubt the course of behaviour, as we observe it to-day in the lives
of many species, is the outcome of, rather than the condition which has
led to, the evolution of the territory. Thus, in many cases, we find
that early mating is the rule rather than the exception; we find that
the sexes frequently separate to seek their food, and fly away
temporarily in different directions; and, under exceptional climatic
conditions, we find that they even revert to their winter routine and
form flocks; only, however, to return to their territories, as pairs,
under more congenial conditions. Yellow Buntings, for example, pair
comparatively early in the season--some in the latter part of February,
others in March, and others again in April; and some build their nests
in April, others in May. There is a gorse-covered common which I have in
mind, a favourite breeding resort of this species. Between this common
and the surrounding country, the birds constantly pass to and fro. If
you watch a particular male you will observe that it sings for a while
in its territory, that it then rises in the air and disappears from
view, and finally that it returns to the tree, bush, or mound which
constitutes its headquarters, where it again sings. Meanwhile the
female, with which there is every reason to believe t