In January 2024, the tidy work of a Welsh mouse, caught on video cleaning the work bench inside a man’s shed, went viral.
Night after night the mouse gathered up clothespins, corks, and other miscellaneous objects, stashing them inside a rectangular wooden box for safekeeping. Each time the man laid the items back out, the mouse had cleaned them up again by the following morning.
While people across the world found the video adorable, many also asked the question: Why did the mouse keep doing this and do other animals like to be orderly?
Why Was the Mouse Cleaning up?
Scientists who study mouse behavior have various theories that range wide for this tidy behavior. Animals who are tidying up could be:
Building a nest or shelter
Hiding food
Creating a barrier against diseases
Mating
Defending themselves or an area
But James C. Ha, an emeritus research professor at the University of Washington, wasn’t surprised to see the Welsh mouse doing its thing. Ha says that in many mice and rat species, foraging behavior is so entrenched that it can be thought of as a ritualized, compulsive behavior that may not even have a practical survival purpose.
“It’s in their genetics,” Ha says. “They can’t not do it.”
In North America, the woodrat (also known as the ‘packrat’ – hence the term for humans who collect lots of stuff) is a prime example of rodents that forage for objects and return them to a shelter. Once safely back home, the rodents typically attempt to either eat the objects or add them to nests. They often forage under the cover of darkness, and sometimes leave objects deemed too heavy or inedible wherever is convenient.
“I can’t tell you how many houses have mice and rats that are doing that,” Ha says. “Where did your sock go? Where did your keys go? They’re probably in the wall, with a rat.”
Read More: Why Are We So Afraid of Mice and Other Rodents?
What Other Creatures like to be Tidy?
Plenty of other rodent and animal species exhibit behavior that will continue to happen regardless of the environment in which an animal finds themselves.
Videos of previously-wild beavers – raised in captivity by wildlife rehabilitation experts – show the rodents building dams out of whatever human objects they can get their paws on. Millions of years of evolution, Ha says, have engrained such behavior to keep beavers and their offspring safe from predators. Whether you describe it as innate, stereotypic, or just plain compulsive, it’s something they just won’t stop doing.
“If you don’t do it, you’re dead,” he says. “You don’t pass on your genes.”
Fish
Pumpkinseed fish – brightly-colored, saucer-shaped sunfish – are another example of tidy behavior for a good reason, Ha says.
The fish lay their eggs in small, circular nests amid shallow sediment, and clear out any debris that may fall into the nest. The theory, Ha says, is that doing so likely improves the water circulation surrounding the eggs, improving oxygenation and keeping fungi and diseases away.
Canines
Wolves and other canine species have been known to chew down bushes and vegetation surrounding their dens, Ha says.
This is likely done for visibility, helping them be more alert to approaching creatures and potential sources of danger.
Birds
Many bird species also exhibit tidying up, clearing areas around their nests for visibility and landing purposes, Ha says. Cleaning up excessive branch accumulation might also prevent potential wing damage, he adds.
Bowerbirds, which can be found in Southeast Asia and Oceania, build large and elaborate nests where they’ve cleared several yards of space. Males will then spread out stones, pieces of glass, or other shiny objects around the cleaned nesting area as a means of attracting a female, Ha says.
Crows and ravens also famously engage in ritualistic foraging behavior for courtship. They pick up coins, bottle caps, and other shiny objects to attract females, but also are known to gift humans with such trinkets in exchange for food. Ha says it’s not known whether these birds do this as intended courtship behavior with people, or merely as ritualized gift exchange; either way, it happens.
Bugs
Even insects get into the cleaning game: Bees and ants remove dead bodies from hives and tunnels – a behavior known as necrophoresis that is done to prevent the spread of disease.
Read More: Otters, Beavers And Other Semiaquatic Mammals Keep Clean Underwater, Thanks To Their Flexible Fur
Psychological Rewards of Cleaning
While disease protection, mating, food storage, defense, and shelter are all reasons an animal might clean up an area, there is also the simple cognitive reward of getting some work done, Ha says.
As with the case of the Welsh tidy mouse, the animal’s dopamine receptor system kicks in when it conducts and completes foraging behavior. The animal’s brain is flooded with feel-good neurotransmitters, which keeps the animal doing its behavior regularly. The same principle can even be ascribed to human behavior regarding shopping and collecting.
“This has been suggested by evolutionary psychologists,” Ha says. “We have genetic variations. There are those who can’t stand clutter and are going to be minimalists, and clear everything, and there’s going to be others that have this innate drive to acquire.”
Although humans and animals vary greatly in their reasoning abilities, it’s easy to see how we also mimic tidying behaviors: cutting down trees and clearing brush to construct our own homes.
“There’s a lot of this clearing the space and throwing the junk away,” Ha says of humans. “But in other species, [they’re] clearing a space [and] picking up the junk because it could be important.”
Read More: Why Do We Hold On To Clutter?
