For some time she had watched his movements, appearing coyly in
his haunts.  And now, had it paid off?  Doubtless, he was in
love. His muscles were taut; he swooped through the air more like
an eagle than a Greylag gander.  The only problem was, it was not
for her that he then landed in a flurry of quacks and wingbeats,
or for her that he dashed off surprise attacks on his fellows.
It was, rather, for another – for her preening rival across the
Bavarian lake.

Poor goose.  Will she mate with the gander  of her dreams?  Or
will she trail him for years, laying infertile egg clutches as
proof of her faithfulness?  Either outcome  is possible in an
animal world marked daily by scenes of courtship, spurning and
love triumphant.  And take note:  these are not the imaginings of
some Disney screen-16 writer.  Decades ago Konrad Lorenz, a famed
Austrian naturalist, made detailed studies of Greylags and
afterwards showed no hesitation in using words like love, grief
and even embarrassment to describe the behavior of these large,
social birds.

At the same time he did not forget that all romance – animal and
human – is tied intimately to natural selection.  Natural
selection brought on the evolution of males and females during
prehistoric epochs when environmental change was making life
difficult for single-sex species such as bacteria and algae.
Generally, these reproduced by splitting into identical copies of
themselves.  New generations were thus no better than old ones at
surviving in an altered world.  With the emergence of the sexes,
however, youngsters acquired the qualities of two parents.  This
meant that they were different from both – different and perhaps
better at coping with tough problems of survival.  At the same
time, nature had to furnish a new set of instincts which would
make “parents” out of such unreflective entities as mollusks and
jellyfish..

The peacock’s splendid feathers, the firefly’s flash, the
humpback whale’s resounding bellow – all are means these animals
have evolved to obey nature’s command:  “Find a mate.  Transmit
your characteristics through time!”  But while most males would
accept indiscriminate mating, females generally have more on
their minds.

In most species, after all, they take on reproduction’s hardest
chores such as carrying young, incubating eggs and tending
newborns.  Often they can produce only a few young in a lifetime.
(Given half a chance, most males would spawn thousands.)  So it’s
no surprising that the ladies are choosy.  They want to match
their characteristics with those of a successful mate.  He may
flap his wings or join a hockey team, but somehow he must show
that his offspring will not likely be last to eat or first in
predatory jaws.

Strolling through the Australian underbrush that morning, she had
seen nothing that might catch a female bowerbird’s eye.  True,
several males along the way had built avenue bowers – twin rows
of twigs lined up north and south.  True, they had decorated
their constructions with plant juices and charcoal.  Yet they
displayed nothing out front!  Not a beetle’s wing.  Not a piece
of flower.   Then she saw him.  He stood before the largest bower
and in his mouth held a most beautiful object.  It was a powder
blue cigarette package, and beneath it there glinted a pair of
pilfered car keys.  Without hesitation she hopped forward to
watch his ritual dance.

Males have found many ways to prove their worth.  Some, like
bowerbirds, flaunt possessions and territory, defending these
aggressively against the intrusion of fellow males.  Others, like
many birds and meat-eating mammals, pantomime nest building or
otherwise demonstrate their capacity as dads.  Still others,
however, do nothing.  Gentlemen may bring flowers, but most male
fish just fertilize an egg pile some unknown female has left in
underwater sand.  For a fish, survival itself is a romantic feat.
For other species, though, love demands supreme sacrifices.

Shortly after alighting on the back of his mate, the male praying
mantis probably had no idea what was in store.  This would have
been a good thing too, because as he continued to fertilize his
partner’s eggs, she twisted slowly around and bit off his head.
She continued to put away his body parts until well nourished and
thus more able to sustain her developing young.

Luckily for most species, the urge to mate come on only
occasionally, usually in springtime.  For love can hurt,
particularly if you intended has difficulty telling a mate from a
meal.  Pity the poor male of the spider species, Xysticus
Cristatus, for instance.  His only hope of survival is to tie a
much larger female to the ground with silk thread, and keep her
there.

Every time a moth releases its attracting scent, or a bullfrog
sings out its mating call, these animals are risking a blind date
with some predator.  Such alluring traits have long puzzled
scientists, particularly those which seem not only risky but
useless as well.  Why, after all, should a frigate bird mate more
if he puffs out an extra large red throat sac?  How does
ownership of such a thing indicate a superior individual?  Until
recently, the question stymied biologists, but then researchers
in the U.S. and Sweden announced a possible answer.  While
studying widowbirds, among whom extravagant tail feathers are
hip, they discovered that the longest-tailed males also carried a
power number of blood parasites.  Sexual ornamentation seemed to
be a means by which males could show of superfluous health and
energy.

All of which may bring us to fast sports cars, flashy clothes and
other accessories of the human suitor.  After all, if he can
afford dinner at the city’s most expensive restaurant, chances
are he could finance a baby too.