Oxpeckers, like egrets, free their furry companions of lice, ticks and other annoyances but of particular importance is their flying scream when predators approach – after all, zebras are more susceptible than many large mammal species (such as elephants and hippos shown above) to potential aggressors. However, their actions are not always completely in the interests of their hosts: they are suspected to sometimes nip open wounds on a zebra’s back in order to encourage more parasites to take root for later meals.