ten quite set aside, and the eye and ear of the mate alone is
appealed to. The males (and also, in some cases, the females) use many
aesthetic appeals to stimulate passion, such as dancing, beauty of
plumage, and the art of showing it, as well as sweetness of song and
diverse love-calls. There are numerous examples of affectionate
partnerships between the sexes, in some cases lasting for life. The
female Illinois parrot, for instance, rarely survives the death of her
mate. Similarly the death of either sex of the _panurus_ is said to be
fatal to its companion. The affection of these birds is strong; they
always perch side by side, and when they fall asleep one of them,
usually the male, covers the other with its wing. The couples of the
golden woodpeckers and doves live in perfect unison. Brehm records the
case of a male woodpecker who, after the death of his mate, tapped day
and night with his beak to recall the absent one, and when at last
discouraged, he became silent and never recovered his gaiety.[58]
According to some estimates monogamy prevails among ninety per cent of
birds.[59] This is explained by the steady co-operation of both sexes
in forming the home and caring for the young, for it is surely the
working together which causes their love to outlast the excitement of
the procreative season. Sometimes we find this affection flowing out
into a wider altruism, extending beyond the family to the social
group; which again is surely at once the condition and result of these
beautiful and practical love-partnerships.

Those who have read the absorbing pages of Darwin devoted to the
consideration of the sexual characters of birds, or know the examples
given by Buechner, Audubon, Epinas, Wallace and other naturalists, or,
better still, those who have watched and noted for themselves the
love-habits of birds, will find it impossible to withhold admiration
for the poetic character of many of these courtships and marriages,
which put too often our own human matings to utter shame.

Let us look first at the love-dances. Dancing as a means of attracting
the right pitch of passion in the male and the female has always been
used in the service of the sexual instinct. It gives the highest and
most complex expression of movement, and may be said to have been
evolved by love from the more brutal courtships of battle display.[60]
The characteristic features of the amatory dances of birds are well
known; they may be witnessed f