Got a rat problem? Try bartering with them

Study shows rats like a fair trade just as much as humans.

Study shows rats like a fair trade just as much as humans

(Credit: iStock/Getty Images)

We reserve our love of sentient creatures for a precious few: dogs, cats, bunnies, goldfish, birds, even squirrels get a little love (that tail goes a long way). Rats, a rodent well-documented as carrying diseases (bad ones) will forever struggle to find favour with us. Yet where people live, there shall you find them — a lot of them. And Canada is no exception.

Experts explain that warmer winters (not this one, a few years back) are responsible for an "absurdly high rate of rats" in Ontario. A New Brunswick pet owner says her dog suffered brutal rat attacks three times in the same week last year. The Vancouver Rat Project (not a post-grunge neo-punk band, but an organization that studies risky rodent goings on) confirmed in October that rat populations were booming. As recently as last week in Quebec, a large colony of Montreal rats were spotted shamelessly squatting in something of a garbage-pile- turned-snow-hotel at a busy intersection in NDG. And Nova Scotia resident, John Sullivan, trapped and killed 23 of them on his property alone this fall — they'd gnawed through his compost bin and extermination professionals in the province explained that "this type of rat isn't scared of humans and can be aggressive." Cool, cool, cool. Alberta, oddly enough, has been deemed relatively rat free for half a century by National Geographic, no less. Go Alberta. The rest of us may have something of a pest problem.

Still, depending on your willingness to cooperate with rodents, you may find recent scientific data reassuring. Researchers at the Institute of Ecology and Evolution at the University of Bern have found that not only do rats appreciate a good trade, they're reliably reciprocal about it — at least within the rat community. Norway rats (aka Rattus norvegicus aka brown rats, one of the species most likely to scuttle through your crawl spaces) appear to favour, well, favours.

The study, lead by Dr. Manon Schweinfurth and Dr. Michael Taborsky, had rats interact with both a cooperative rat partner and a non-cooperative rat partner during two potentially reciprocal activities: food sharing and allogrooming. Allogrooming may sound like a french pet salon, but it's a common zoological term for social grooming behaviour within species.  

Credit: Schweinfurth and Taborsky, Reciprocal Trading of Different Commodities in Norway Rats, Current Biology (2018)/Via: doi.org

Once rats were paired up, researchers applied saltwater on tough-to-reach back and neck fur, which prompted a little partner grooming. For food provisioning, cooperative and non-cooperative rats were given the chance to pull food items closer to their partners. Almost adorable (also, gentle reminder that rats laugh when tickled). More crucially, the rats that got a little help from their friend were then provided the opportunity to return the favour with a comparable commodity or service (snacks or fur preaning). The resulting data was compelling: rats don't just get reciprocity, they display an understanding of fair "pay" or trade using different currencies.

Case in point, rodents consistently groomed their cooperating food providers more often than non-cooperative ones, and they shared food more frequently with those who'd been lax and liberal with the grooming love. Researchers write that this concretizes "experimental proof of tit-for-tat-like exchange of different services in animals." They also assert that their study is the first of its kind to offer evidence that non-human, non-primate animals barter.

Long-tailed macaques, for example, understand commodity and wield that knowledge craftily — they'll steal your stuff and sell it back to you for a snack. Some social insects like termites, bees, wasps and ants have also been found to work collectively and cooperate. Bees, for instance share babysitting duties. But scientific evidence of similar commodity trading in other animals has been rare. One of the pervading theories to support us not seeing much bartering outside the study of primate behaviour is the presumably high cognitive demands of engaging in "reciprocal cooperation". So either smarts aren't the crux of good trade policies, or rats are much brighter than we've assumed. Schweinfurth told media that the study's "result indicates that reciprocal trading among non-human animals may be much more widespread than currently assumed. It is not limited to large-brained species with advanced cognitive abilities."   

Until we trade our bird feeders for rat feeders, I'll venture that bartering isn't going to be a go-to pest management solution destined to improve rat/human relations (memories of the Plague will die hard). But maybe the idea of rats helping one another is at least endearing enough to coax you down from that chair you're standing on. Of course, you're welcome to stay right where you are and call an exterminator. No judgement.


Marc Beaulieu is a Montreal writer, producer, performer, professional host and mental health advocate whose one true love is weird news.