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exists, though it may he only a couple of feet across. In what we may
call the true territorial birds, or birds with feeding as well as nesting
territory, the course of events is as follows ([ follow in this particular
Eliot Howard's admirable description of the course of events in the
European warblers or Sylvlidac}. The males are first on the breeding-
grounds. If the species be a spring migrant, the males generally
migrate north a week or so ahead of the females. Arrived, they take
possession of an area—a territory—sometimes without dispute, some-
times after a fight with a simultaneous arrival or a bird already in
possession. Then they begin their singing. Contrary to usual belief,
the song of most song-birds is at its best before the mate has even
arrived. As Howard has, I think, convincingly shown, the prime
function of song is an advertisement. It is an advertisement of
eligibly-occupied territory, which serves the double purpose of at-
tracting females and warning off other males. Similarly, many of the
special display-characters of males are used in threat-display against
other males as well as in courtship-display to females.
When the females arrive on the scene, no immediate courtship on
the part of the males is to be observed. If the female is alone, she
simply takes her place in the territory, and the two are a pair for the
season. Nature abhors a vacuum, and this particular vacuum, the
absence of the female from a territory, is filled with the least possible
fuss. If two rival females arrive together, it is they who fight for the
possession of territory-plus-male, while he hovers about, an interested
and even excited spectator, but without participating. Then follows
the strange fact, which at first sight seems to upset the whole Dar-
winian apple-cart, namely that courtship and display now begin
vigorously—only now, after the two birds arc mated for the season.
The male vibrates his wings, spreads his tail, puds his feathers, bows
and scrapes, runs before his mate, often with a leaf or twig or other
piece of nest material in his beak, and his antics may be so extravagant
as to testify to the most ardent excitement within. How can this be
fitted in with Darwin's view that these antics and displays have been
evolved in large measure through the female's selection? To this,
what we have learned from the lowly newt provides the answer.
Courtship and display need not always have as their chief result the
choosing of a mate. They may be, and indeed normally appear to
be, accessory to the act of pairing and fertilization itself. The mind
of a bird is a complex thing, and so is its life; the bird cannot always
be tuned to a sexual situation. The simplest way, it would appear, of
ensuring that it is not always so tuned (with consequent excessive
pairing), and yet of ensuring that both sexes shall be simultaneously