We've all seen those photos of large animals on the African savannah with birds on their backs, right? And we've heard that those birds, aptly called Oxpeckers (family Buphagidae), have a symbiotic relationship with those animals, eating the ticks that would otherwise bedevil them?
Well, the truth is not so simple. Oxpeckers do eat ticks, but they eat only one species (the Blue Tick) and they prefer to eat them only after they've already laid their eggs. Oxpeckers eat earwax, which might help the host animals hear better, but decreased earwax could lead to increased ear infections. Worst, Oxpeckers pick at the open wounds in the hides of the host animals and have even been known to make the wounds themselves. (Ick!)
Dr. Paul Weeks has researched the Red-billed Oxpecker (Buphagidae erythrorhynchus) in Zimbabwe, publishing two studies in 1999 and 2000. Neither one indicates that animals benefit much from Oxpeckers.
Weeks separated cattle into two matched groups, then prevented Oxpeckers from coming into contact with one of the groups. At the end of two weeks, he compared the health of the animals.
The cattle in the control group (the ones with the Oxpeckers) did not have significantly fewer ticks than the experimental group (the protected ones). What the control group DID have was less earwax and more wounds. Net benefit to the animals? Zilch, or at least close to it.
So the next time you see one of those Oxpecker-and-rhino photos touted as showing "the beauty of symbiosis," go ahead and snort like a rhino.