are certain
peculiar behaviors of the animal during the mating season which are
intensely interesting. Sometimes they consist simply of a wild
delirium of joy, which overpowers the animal completely and makes him
do wonderful things. Birds will fly with impetuous leaps in the air,
mount higher and higher, singing wildly, only to turn suddenly at the
top of the flight and drop promptly to the ground. I have seen such
ecstatic flights in the oven bird and in our rollicking gold finch. I
have seen a catbird on his way to a tree turn three somersaults, much
like those performed by a tumbler pigeon, after which he alighted upon
the bough. None of these acts seemed deliberately performed in front
of the females, but I have seen three or four killdeer parading in
most stately and precise manner, spreading their wings and fluffing
their feathers, performing a sublimated cup-and-cake walk amid a
circle of attracted females.

Even our little English sparrow, as I have previously mentioned,
fluffs himself up and spreads his wings and prances around in front of
his presumably adoring ladylove. But the weirdest performance of this
sort I have ever seen is that shown by the male ostrich. When he
becomes excited, swaying his body from side to side, he sinks slowly
upon his knees, until his body touches the ground, his wings spread on
either side and the feathers fluffed up so as to show every exquisite
plume in all its splendid beauty. The long neck is laid back until the
head, which is doubled sharply forward, is pressed almost against the
back, and in this strange position he sways from side to side,
apparently utterly oblivious, for a time, of everything. After about a
minute of this performance, he seems slowly to come to himself and
rise again to his feet. Now he is particularly likely to make vicious
attack upon anything within reach.

It is not only necessary that the animal should be able to attract a
mate. There may be more than one claimant for the damsel's affection.
In many animals we see provisions whereby the male may effectively
deal with his rivals. This is especially likely to be the case if the
animal be a polygamist. In every species there are produced about as
many males as females. If the polygamous habit leads one male to
gather about him a group of females, with whom he mates, it is evident
that he is displacing an equal number of rivals, and they are not
willingly displaced. Accordingly we find that polygamy