Figure 17.12 Oxpecker preferences for different species of mammals. The preferences of red-billed oxpeckers and yellow-billed oxpeckers are positively correlated to the abundance of ticks on the different mammals. Neither bird showed a preference for mammals with thin hides. These data suggest that oxpeckers seek out particular species of mammals primarily to consume ticks as a mutualist rather than to consume bits of mammal flesh as a parasite.

Data from C. L. Nunn et al., Mutualism or parasitism? Using a phylogenetic approach to characterize the oxpeckerungulate relationship, Evolution 65 (2011): 1297–1304.