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Deceptive cads
of the savanna
By Rachel Ehrenberg
As any dating woman knows, men can
be dogs — but a new study suggests that
antelopes might be a better fit.
Male topi antelopes resort to deception
to keep a potential mate around, snorting
as if there’s a lion nearby when it seems
she might wander off. It’s the first report
of outright mate deception in an animal other than Homo sapiens, scientists
report in the July American Naturalist.
Some birds will feign a broken wing to
lure a predator away from their nest, and
there are reports of male monkeys and
squirrels deceiving other males in the
heat of competition. But the male antelope behavior “is the clearest example
of tactical deception between mates in
animals other than humans,” comments
Cornell University’s H. Kern Reeve, an
expert in the evolution of cooperation
and conflict in animal societies.
Study leader Jakob Bro-Jørgensen
Male topi antelopes will falsely warn of a
predator to keep a female (right) nearby.
discovered the devious behavior while
studying topi antelopes at the Masai Mara
National Reserve in Kenya. Female antelopes are sexually receptive for one day
only, and they spend that day visiting several males, munching grass and mating.
Bro-Jørgensen noticed that when a
female started to wander away from a
male’s territory, the male would look in
the direction she was headed, prick his
ears and snort loudly— the same snort
the antelopes use when they notice a lion,
leopard or other predator approaching.
“It was quite funny—it made me
laugh,” says Bro-Jørgensen, an evolution-
ary biologist at the University of Liver-
pool in England. “It’s such an obvious lie.
Clearly there’s no lion.”
Suitors in nature often exaggerate their
virtues. But this work documents a rare
case in which evolution favors outright
lying in the mating game, Reeve says. The
cost of the lie is minimal to the male; he
merely snorts. But the cost to the female
of ignoring the lie could be great: If there
truly is a predator nearby, she’s dead.
Argonaut casing offers lift
after centuries of speculation, biologists have documented a way
that female argonauts, which belong to a group of four species
closely related to octopuses, use their delicate white shell-like
cases. it turns out the animals trap air bubbles in the cases to
float at a comfortable depth, Julian Finn and mark norman of
museum victoria in melbourne, australia, report online may 19
in Proceedings of the royal society B. When Finn maneuvered
argonauta argo females so air escaped from their cases, the
animals flailed as if to maintain their orientation and quickly
jetted to the water surface. there they rocked their cases and
took on air, then positioned body parts to seal in some of the
air and jetted downward, leaving behind a trail of bubbles. When
the argonauts stopped several meters below the surface, water
pressure compressed the remaining air inside the cases enough
to counteract the animals’ weights, leaving the argonauts floating neutrally buoyant at a chosen depth. — susan milius
FRom top: J. BRo-JøRgEnsEn et al./american naturalist; J. Finn, mUsEUm victoRia
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