The mammal kingdom is a world awash in odors, which pepper habitats like billboards along a freeway. And, like billboards, scents are often used as advertisements of sex or identity, as a pair of Czech zoologists recently found in a study of wild white rhinoceroses. White rhinos spend roughly a minute snuffling dung piles of strangers, compared with a 20-second sniff over feces of familiar rhinos, report the researchers in the journal Animal Cognition.
It's the first time southern white rhinos' dung-smelling habits have been recorded in the wild, the scientists say. Scent is particularly important for white rhinos, whose poor eyesight means a sharp sense of smell plays a prominent role in communication. Rhinos were also much less likely to remain alert when smelling a recognizable male rhino's droppings, perhaps because they then went in search of the familiar bull.
Poop isn't the only way that these animals communicate - but it's an easy signal to study, the zoologists point out, as opposed to collecting, say, urine. Rhinos return to common dung piles (think "Jurassic Park's" Triceratops droppings mound, but smaller) to mark their territory, ensuring that both the message persists and that the researchers had a constant supply of fresh feces.
Because the rhinos in the study all ate similar food, different vegetable smells aren't a likely culprit for the prolonged sniff sessions; instead, evidence points to rhinos excreting chemical cues unique to each individual.
It's a critical time to learn as much as possible about the remaining white rhinos, who are increasingly threatened by the demand for poached horns. There are only seven northern white rhinos remaining - "one of the most endangered mammals in the world," the scientists write.
Four of the northern rhinos live in the Ol Pejeta Conservancy, a sanctuary in East Africa, with the yet-to-be-realized goal of having the animals breed. Understanding how these incredible creatures communicate with each other, in scent and sound, could let conservation biologists mimic the company of additional animals. And giving the impression of a larger population, the zoologists say, could improve the chances the rare rhinos will reproduce.