itories; we watch the summer migrants on their way--small parties
halting for a few hours in the hedgerows and then continuing their
journey, single individuals alighting on trees and bushes and resting
there for a few minutes, and the constant passage of flocks of various
dimensions at various altitudes; and we see Fieldfares, Redwings, and
Bramblings slowly making their way from the south and the west to their
homes in the far north. Occasionally we hear their song, not the
emotional outburst customary at this season, but, except in isolated
cases, a weak and tentative performance. Gaetke speaks of the absence of
song on the Island of Heligoland, and refers to the Whitethroat as one
of the few migrants that enliven that desolate rock with their melody.
On the other hand, many migrants that rest temporarily on the Isle of
May sing vigorously.[5] But on the whole there is, I think, no question
that the male whilst travelling to its breeding grounds, and, even after
its arrival, whilst in search of a territory, sings but little--and that
little lacks the persistency characteristic of the period of sexual
activity. Yet, when a suitable territory is eventually secured, the
nature of the bird seems to change; for, instead of being silent and
retiring, as if aware of some end not fully attained, it not only makes
itself conspicuous but advertises its presence by a song uttered with
such perseverance as to suggest that that end is at length attained.
Hence, in a general way, the instinct of song seems to be related to the
establishment of a territory.

Now the subsequent course of behaviour tends to confirm this view. We
have already had occasion to refer to the fact that the males of some
species desert their territories temporarily and join together on ground
which is regarded by the birds that associate there as neutral, and that
they do so not merely for the purpose of securing food but because they
derive some special pleasure from the act of association, and we shall
find that the altered behaviour of the male when it leaves its territory
to seek food or to join the flock is an important point for us just now.

Buntings desert their territories temporarily and collect in flocks on
the newly sown fields of grain. Some of the males are single, others are
paired, and accompanied, it may be, by their mates; they wander over the
ground in search of food, uttering their call-notes from time to time,
or, settling upon the hedg