do tick birds help rhinos see

Red-billed oxpeckers that feed on rhinos’ ticks alert them to approaching humans, likely helping the poor-sighted animals survive.

In sub-Saharan Africa, red-billed oxpeckers feed on the parasites of rhinos and more than 20 other species of mammal. Now, new research suggests the birds may also serve as sentinels that help rhinos avoid humans—and potentially poachers.

Though black rhinos have a good sense of smell and good hearing, they have notoriously bad vision. If you know where one is and stay downwind of it, you can often get quite close to the animal, says Roan Plotz, now a researcher at Victoria University in Melbourne, Australia.

While Plotz was completing his doctoral thesis on black rhinos in Hluhluwe-Imfolozi Park, in eastern South Africa, he began contemplating how black rhinos might avoid humans. In recent years, poachers have decimated the ranks of the black rhino, which in adulthood can weigh a ton and a half. Today, the critically endangered species’ population is a little over 5,000, a tenfold decline since the 1970s.

While studying black rhinos, Plotz found that those close enough for him to observe generally didnt have any oxpeckers on their backs. The birds have good vision and make hissing alarm calls when certain threatening animals—such as humans—approach. Is it possible, he wondered, that oxpeckers were alerting the rhinos to his presence? Such a phenomenon is hinted at in the oxpeckers Swahili name, Askari wa kifaru—which translates to the “rhino’s guard.”

When Plotz set up an experiment to test his hypothesis, it proved true: Rhinos accompanied by the birds were more likely to detect humans, and from further away, compared to animals without oxpeckers.

For the experiment, Plotz and colleagues put radio trackers on 14 rhinos in Hluhluwe-Imfolozi, one of the oldest nature reserves in Africa. They then conducted on-the-ground surveys for both tagged and untagged rhinos on a near-daily basis over the course of 27 months. The tagged animals were easy to locate using radio telemetry. Finding the untagged rhinos was more difficult, and required the researchers to roam the landscape looking for the animals.

Of the hundred untagged rhinos the research team saw, only 17 had oxpeckers riding on them. “That seemed quite low,” Plotz says, and likely not representative of the true number of rhinos with oxpecker tagalongs. As a control for the experiment, the team located one of the 14 tagged animals on a hundred different occasions over the study period. Of those sightings, the majority—56—recorded oxpeckers perched on the animal’s hide.

The discrepancy strongly suggested that the oxpeckers on the untagged rhinos were warning their hosts about the scientists’ presence.

To better understand the rhino-bird relationship, Plotz and colleagues did further tests. They conducted 86 trials in which they approached tagged rhinos that were and were not accompanied by oxpeckers.

Every time that a tagged rhino had one or more oxpeckers on its body, it showed physical signs that it had detected a human: standing bold upright, facing downwind, and preparing to run. But when the rhinos were not accompanied by the birds, they showed signs of recognizing the human’s approach only 23 percent of the time.

For detecting humans, having more birds on board seemed to be an advantage to the rhino. In the trials, each additional bird perched on an animal was associated with sensing the human 30 feet further away, on average.

When Plotz and colleagues did a mathematical analysis of all their research, they concluded that the oxpeckers reduced human’s likelihood of a rhino sighting by 40 to 50 percent.

The research findings show that the oxpecker-rhino relationship is more complex and potentially mutually beneficial than previously thought, Plotz says. They also could have implications for conservation, suggesting that introducing the birds into areas where they’ve been depleted might help avert poaching.

A way to combat poaching?

Regarding the oxpeckers’ intentions, Plotz notes that it’s not apparent if they are aware that they are warning the rhinos. Perhaps all they are doing is warning other oxpeckers about the possible predator’s presence.

Amanda Ridley, a biologist at the University of Western Australia, takes issue with framing this as the oxpeckers “warning” the rhinos about humans.

“There is no proof that oxpeckers purposefully alerted rhinos to the oxpecker alarm call, even though rhinos may have responded to it,” she states.

Judith Bronstein, a professor at the University of Arizona, agrees—but says that doesn’t diminish the importance of the paper.


“While listening in on the signals of other species is a well-documented adaptive behavior, its distribution in the natural world is not well understood,” the statement reads. “This carefully thought-out example features big, solitary mammals, which is novel. ”.

Whatever the reason behind the oxpeckers’ calls, Bronstein continues, they could lessen poaching by warning rhinos to humans at a distance where guns would be less accurate.

According to Plotz, poaching may be decreased by reintroducing the birds to areas where the populations of oxpeckers and rhinos have declined. This potential intervention should be further researched. Many areas have seen the extinction of red-billed oxpeckers due to the unintentional killing of the birds that feed on the parasites that are killed when pesticides are applied to livestock.

Plotz believes that reintroducing oxpeckers into black rhino populations could be beneficial. ”.

Victoria University of Melbourne behavioral ecologist Roan Plotz. However, those defense mechanisms are ineffective against armed humans. Today the species is critically endangered largely due to poaching. But the red-billed oxpecker might be an unexpected ally of the rhinos in their fight against poachers. The chatty and gregarious birds frequently perch on rhinos’ backs where they feed on parasitic ticks.

Which makes sense because the more people watching out for you and keeping an eye on you, the greater the likelihood that they will notice anything suspicious. Without a doubt, the fundamental theory behind this is that the rhino is listening in on the oxpecker’s alarm call. A powerful antihuman benefit can be derived from listening to oxpecker alarm calls. ”.

The researchers discovered that, at an average distance of 27 meters, rhinos without oxpeckers only identified an approaching human 23% of the time. However, 100% of the time when oxpeckers were present, the birds warned the rhinos. And they detected the human 61 meters away on average. Additionally, the greater the detection distance—which indicates the earlier the warning—the more oxpeckers there are.

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Taken together, the results show that “black rhinos are able to eavesdrop on oxpecker alarm calls and by doing so, detect approaching humans at substantially greater distances,” says Daniel Blumstein, an ecologist at the University of California Los Angeles, who wasn’t involved the paper, in an email interview.

Blumstein was particularly intrigued by the “dose-response,” which refers to the fact that an oxpecker on a rhino increases the distance at which it detects a human approaching.

The paper, published Thursday in Current Biology, is “a genuinely astonishing study,” said Darryl Jones, a researcher at Griffith University. But Jones acknowledged that “the local peoples of these regions would probably be less impressed, having known about this relationship for millennia.

That is, in fact, one of this study’s greatest accomplishments: verifying a significant example of traditional knowledge using modern techniques. ”.