Page 40 - BBC Wildlife Volume 36 #10

In
focus

Hitching a ride

Like a bevy of beauticians, yellow-billed
oxpeckers line up to remove, deftly, engorged
ticks and biting insects from the neck of a
Maasai girafe. One spots a passing fly and
takes of to snatch it, beating the others
to the prize. Scenes like this in Kenya’s
Maasai Mara were long held up as a textbook
example of mutualism, in which two species
work together for shared benefit. The
oxpeckers have stout, flattened bills for
scissoring through the fur of their hosts –
which also include African bufalo, rhino,
zebra and antelopes – as well as long claws
for holding on. Meanwhile, the herbivores
benefit by being rid of troublesome parasites.
But then closer study revealed that the birds
were also sneaking meals of blood from
the bites, making wounds worse, and that
their feeding actually had no impact on the
overall number of ticks, fleas or flies. So the
relationship between oxpecker and mammal
is not purely mutualism: sometimes the birds
are themselves parasites. Their services do
not come without a cost.
Photo: Varun Aditya

40 BBC Wildlife October 2018