Most people have a preferred way of communication - phone, text, email - but bare-nosed wombats have an unusual way of relaying information.
The Australian marsupial communicates by … there's no delicate way to say this … poo.
Led by the University of Georgia's Scott Carver, a new study published in the Journal of Zoology considers whether the marsupials from down under are communicating through the unusual scat that they deposit in common latrines across southeastern Australia.
The research follows earlier work that won Scott Carver the 2019 Ig Nobel Prize for physics, a satirical prize awarded for science that makes people "laugh, then think." In that research, Carver and collaborators investigated how wombats create square-shaped poos, finding that the unique shape and structure of the animal's lower intestine create feces that resemble charcoal briquettes.
"People always say, 'But why do wombats produce cubes?'" said Carver, corresponding author of the study and a professor in the UGA Odum School of Ecology. "And this research was much more about addressing that. What is the functional role of cube-shaped feces for wombats?"
Why square poop?
Wombats are antisocial creatures, avoiding interactions with one another except for mating and rearing young. They change burrows every few days, often returning to a previous home. As nocturnal animals, their eyesight isn't great. Yet, they poop in common areas called latrines, and their square poop stays put, rather than rolling away.
"There are signs that these latrines are important in wombats. They find objects, like logs or large rocks that are prominent points in their landscape, and aggregate their feces around them," Carver said. "We had an inclination that this was about olfactory communication, but there's just no research out there about it."
Under Carver's guidance, student researcher Kate McMahon at the University of Tasmania began studying the anatomy of wombats, investigating whether they have nasal structures that support a strong sense of smell. Turns out wombat skulls contain a vomeronasal organ that's responsible for an exceptional sense of smell.
"If you see your cat screwing up their face, that is them actually exposing scents in the environment to their vomeronasal organ," Carver said. "With snakes, this response is really obvious because they basically draw their tongue back over their vomeronasal organ.
"Dogs do it a little bit as well, but in primates, this feature is really reduced."
With a similar structure in their nasal cavity, wombats appear to have a good sense of smell, but researchers didn't know what that might be telling them.
What are wombats saying?
Next, the researchers took wombat poo and broke it down into chemical signatures using gas chromatography and mass spectrometry.
"We were able to show that there are individually distinct chemical signatures - or individual odors - in wombat poo. Wombats have good sensory structures for smell and individually distinct chemical mixtures, so they can probably tell individuals apart," Carver said.
Exploring whether each wombat is communicating its presence and learning who else is around, the researchers took poos from a distant latrine, put them in a latrine outside of the original neighborhood and set up a wildlife camera to see how the wombats would react.
"What we found is that is that they actually spent much more time investigating latrines that had non-resident individual scats added to them," Carver said. "So, they could detect when a new individual arrived in their population or in their local area just by the presence of the scats alone."
What are wombats learning?
While wombats seem to recognize different individuals from the chemicals in their poo, the researchers suspect the animals are also learning about their neighbors' sexes, ages, reproductive statuses and more.
The researchers found 44 distinct compounds in wombat poo, allowing scientists to begin to tease out what each one means to the wombat.
"These were all small experiments to get a good baseline of different aspects of wombats' communication. In the future, we could do a lot more to understand the chemical compounds and signals associated with olfactory communication in wombats and in mammals in general," Carver said.
Ultimately, we all are curious about what animals around us learn with their sense of smell, Carver said.
"What makes this relatable is that a lot of us have pets like cats and dogs, and we see them sniffing forever at a bush, and we know they are getting something that we don't know," Carver said. "They have this much more complex world of smell.
"And, here we have wombats, this quirky, iconic animal from Australia that lives a solitary life," he said. "If you're a solitary animal, how do you communicate with others around you?"
Maybe, you just poo.
