The Onion reports:

“Feed off the embedded ticks on his hide, chirp when the predators come. Feed off the embedded ticks on his hide, chirp when the predators come. Where’s the passion, the heat?” the tickbird continued.

The rhino and tickbird pass another morning on the African savannah not saying one word to each other. - The Onion

Amusing article aside, it is true that rhinos and tickbirds may not get along as well as you think.

The diet of tickbirds, also known as oxpeckers (family Buphagidae), consists of parasites such as ticks. These parasites are in abundance in the hides of large mammals. Thus tickbirds are often found on the backs of these large mammals, pecking away.

On the surface, both animals benefit from this relationship. The oxpecker enjoys a guaranteed source of food, while the host mammal is rid of parasites. According to Wikipedia, this is a symbiotic relationship! We trust Wikipedia, right?

However, it is not clear if the oxpeckers even reduce tick loads. More after the jump.

Some studies have been done on this issue, with varying results.

• Stutterheim et al. (1988) artificially infested oxen with a known number of ticks, and let oxpeckers forage on them. The birds significantly reduced tick loads over a period of 7 days.
• Weeks (2000) observed two groups of oxen, one of which did not have contact with oxpeckers. It was found that preventing oxpeckers from foraging on oxen did not change tick loads.

Studies also found that the oxpeckers can cause adverse effects on the host mammals.

• Weeks (2000) found that the group of oxen with oxpeckers had more wounds and larger wounds, as compared to those which did not. Also, a higher proportion of wounds were persistent or recurring in the former group.
• McElligott et al. (2004) confirmed that oxpeckers do inflict new wounds on the rhinos they foraged on. The rhinos were intolerant of the presence of oxpeckers at their wounds, but were usually not successful at chasing the oxpeckers away.

Furthermore, Weeks suggests in Weeks (2000) that there may not be a clear-cut description of the relationship between the oxpecker and its host mammals. The oxpeckers may behave differently, depending on factors such as the time of year or the species of host mammal. Mysterious!

Meanwhile, somewhere in South Africa:

The rhino said that he often feels like a victim of her nitpicking.

“I might look tough, but I have feelings,” the rhino said. “I give her plenty to eat and a great place to perch, but it feels like she’s constantly pecking an open wound. Ugh, why can’t we just be friends with mutualistic benefits?”

References:

1. “Rhino, Tickbird Stuck In Dead-End Symbiotic Relationship”, The Onion, 22 Sept 2007. URL: http://www.theonion.com/articles/rhino-tickbird-stuck-in-deadend-symbiotic-relation,2287/ (accessed on 04 Apr 2010).
2. Stutterheim IM, Bezuidenhout JD, Elliott EGR, 1988. Comparative feeding behaviour and food preferences of oxpeckers in captivity. Onderstepoort J Vet Res 55: 173 – 179.
   
3. Paul Weeks, 2000. Red-billed oxpeckers: vampires or tickbirds?. Behavioral Ecology Vol. 11 No. 2: 154 – 160.
4. Alan G. McElligott, Ivan Maggini, Lorenz Hunziker, Barbara König, 2004. Interactions between red-billed oxpeckers and black rhinos in captivity. Zoo Biology, Vol. 23 Issue 4: 347 – 354.