Travel Reference
In-Depth Information
watched as crowds of red-billed oxpecker birds strutted undisturbed over the
faces and shoulders of a large herd of Cape buf alo in Botswana's Okavango
delta. The birds were dining well on ticks and botfl y larvae that had attached
themselves to the buf alo, often enthusiastically thrusting their heads up
their hosts' nostrils in the process.
The mutual benefi t here was obvious. The buf alo get to live blessedly
tick-free lives and the birds get to nibble on blood-fi lled tick canapés. The
oxpeckers have even been observed to press a little blood from the animals'
bites as they pull the insects free. But their buf alo hosts do not begrudge
the birds this extra little amuse-bouche , because the relief that the oxpeckers
provide is so palpable.
Oxpeckers perform their ministrations on many dif erent species of graz-
ing animal, enhancing the quality of their various hosts' lives while at the same
time benefi ting themselves. And they have infl uenced the behaviors of their
hosts, who tolerate the most intimate ministrations of these cheery birds.
The oxpeckers and their hosts do not form a true super-organism. Much
of the time the birds must live separate lives from the grazing animals. They
must fi nd mates, build nests, and feed their young, all the while being alert
to a wide variety of predators. The grazing animals, too, live lives that are
benefi ted by, but are largely separate from, the oxpeckers. The perils that
they face from lions, leopards, and cheetahs are just as great as if the oxpeck-
ers were not there.
There is a whole range of mutualistic interactions that lie along the spec-
trum between the kind of intimate association that exists between Cape
buf alo and their fermenting microbes and the more casual but still friendly
interactions between the buf alo and their oxpeckers.
It would be lovely if all organisms could cooperate, like the Cape buf alo
and the oxpecker, or the hoatzin and its thriving microbes. Then the world
might come to resemble American Edward Hicks' famous painting The Peace-
able Kingdom , in which the lion lies down with the lamb. But cooperation,
though it is often favored by natural selection because it produces a super-
organism, can only extend so far. The super-organism must still compete for
food and defend itself against danger. All cannot be sweetness and light in the
biological world. Sooner or later, even super-organisms must eat or be eaten.
 
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