-as, for example, the hawks--in which the
female is usually the larger and finer bird.[34] Thus the adult male
of the common sparrow-hawk is much smaller than the female, the length
of the male being 13 ins., wing 7.7 ins., and that of the female 15.4
ins., wing 9 ins. The male peregrine, known to hawkers as the tiercel,
is greatly inferior in size to his mate. The merlin, the osprey, the
falcon, the spotted eagle, the golden eagle, the gos-hawk, the
harrier, the buzzard, the eagle-owl, and other species of owls are
further examples where the female bird is larger than the male. Among
many of these families the female birds very closely resemble the
males, and where differences in colour and ornament do occur, they are
slight.

A further point of the greatest importance to us requires to be made.
Wherever amongst the birds the sexes are alike the habits of their
lives are also alike. The female as well as the male obtains food, the
nest is built together, and the young are cared for by both parents.
These beautiful examples of sex equality among the birds cannot be
regarded as exceptions that have arisen by chance--a reversal of the
usual rule of the sexes; rather they show the persistence of the
earlier relations between the female and the male carried to a finer
development under conditions of life favourable to the female. I will
not here say more upon this subject, as I shall have to refer to it in
greater detail when we come to consider the sexual and familial habits
of birds. I will only add that in their delicacy and devotion to each
other and to their offspring, birds in their unions have advanced to a
much further stage than we have in our marriages. These associations
of our ancestral lovers claim our attentive study.

II.--_Two Examples--The Beehive and the Spider_

"At its base the love of animals does not differ from that of
man."--DARWIN.

For vividness of argument I wish in a brief section of this chapter to
make a digression from our main inquiry to bring forward two
examples--extreme cases of the imperious action of the sexual
instincts--in which we see the sexes driven to the performance of
their functions under peculiar conditions. Both occur among the
invertebrates. I have left the consideration of them until now because
of the instructive light they throw upon what we are trying to prove
in this first attack on the validity of the common estimate of the
true position of the sexes in N