xercises dominion, no male can
approach without being attacked. The conclusion, therefore, seems to be
inevitable, namely that the actual occupation of a territory is the
condition under which the pugnacious nature of the male is rendered
susceptible to appropriate stimulation.

CHAPTER IV

THE RELATION OF SONG TO THE TERRITORY

If we listen to the voices of the Waders as, in search of food, they
follow the slowly ebbing tide, we shall notice that each species has a
number of different cries, some of which are uttered frequently and
others only occasionally. Not only so, but if we study the circumstances
under which they are uttered, we shall in time learn to associate
certain specific notes with certain definite situations.

The Curlew, when surprised, utters a cry with which most of us, I
suppose, are familiar; but when with lowered head it drives away another
individual from the feeding ground, it gives expression to its feelings
by a low, raucous sound, which again is different from its cry when a
Common Gull steals the _arenicola_ that has been drawn out of the mud
with such labour.

Thus we come to speak of "alarm notes," "notes of anger," "warning
notes"--naming each according to the situations which normally accompany
their utterance. And so, all species, or at least a large majority of
them, have, in greater or lesser variety, cries and calls which are
peculiar to certain seasons and certain situations; and since on many
occasions we have indisputable evidence of the utility of the sound
produced--as when, upon the alarm being given by one individual, the
flock of Lapwing rises, or when, in response to a particular note of the
parent, the nestling Blackcap ceases to call--so are we bound to infer
that all the cries are, in one way or another, serviceable in furthering
the life of the individual.

But besides these call-notes, birds produce special sounds during the
season of reproduction--some by instrument, others by voice, others
again by the aid of mechanical device. And not only is this the case,
but many accompany their songs with peculiar flights, such as soaring to
a great height, or circling, or floating in the air upon outstretched
wings. These special sounds and special flights are those with which I
now propose to deal, including under the heading "song" all sounds
whether harsh or monotonous or beautiful, and whether vocally or
otherwise produced; and I shall endeavour to show not onl