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10 Bizarre Facts about Mice (That Aren’t Cheesy)
For most people, their views on mice don’t go beyond considering these rodents as either pests or pets. But these furry critters lead a strange existence that few are aware of. From an island where the common house mouse has evolved into something terrifying to mice that regrow body parts, here are 10 fascinating reasons you’ll never look at mice the same.
10 Japan’s Unique Rodent Outbreaks
Japan is known for remarkable homegrown architecture, traditions, and crafts. But the country has another unique claim to fame. Every 120 years, a rare event called “masting” occurs. This is when the dwarf bamboo (Sasa borealis) flowers, seeds, and dies off on a massive scale.
According to legend, masting is also behind the widespread rodent outbreaks that occur during the same time. But it wasn’t until 2022 that researchers from Nagoya University in Japan confirmed that the legend was indeed fact. As it turns out, the bamboo is a boon to Japanese field mice, providing them with ideal breeding conditions and tons of seeds as food.
Remarkably, the study also found that the positive effects of masting on mouse populations last for as long as two years after the event, even though the bamboo is long gone. However, this is not a wonderful time for agriculture and forests, as widespread plant damage and tree die-offs have also been linked to these rodent outbreaks.
9 Unknown Semi-Aquatic Mice
About a century ago, a mouse was captured in a stream in Ethiopia. Long, broad paws and waterproof fur showed that it was adapted to living in water. It was the only specimen of its genus, Nilopegamys, to be found, and it’s now considered extinct.
However, other mice were splashing around in rivers across western Africa and the Congo Basin. For years, this species was studied, but it wasn’t until recently that researchers confirmed a few facts.
They were indeed semi-aquatic mice that also had water-resistant coats and long, kangaroo-like legs to better navigate their wet environment. However, it wasn’t one but two species new to science: Colomys lumumbai and Colomys gosling.
DNA tests also confirmed that they were related to Nilopegamys, the specimen caught in Ethiopia. This makes the two living water mice some of the rarest animals in the world.
8 The Mysterious Mountain Mice
The Andes Mountains in Patagonia have a mystery. The area is home to Abrothrix hirta, an adorable mouse known for its soft, shaggy hair. But even though they are the same species, these mice have different sizes, and researchers are not quite sure why.
More bizarrely, how big or small they are depends on where they live on the mountains, with the eastern population growing to larger sizes than their kin on the eastern side.
So, what’s influencing the same species to bulk up or tone down? It might be something called the rain shadow effect. This is when clouds are forced higher when they pass over mountains, a phenomenon that triggers rainfall on the first side of the mountain the clouds hit. In this region, the rain shadow effect causes more showers on the mountain’s western slopes.
More rain means more food. Plenty of food ensures better-fed mice and bigger specimens. That’s the theory anyway, and scientists admit that they do not fully understand how this process might work.
7 The Mouse That Cleaned a House
Actually, it was more of a shed. It all started a few years ago when Stephen McKears noticed that someone was tidying his workbench inside the shed every night. More precisely, small metal items he took out of a box kept mysteriously returning to the same container.
To catch the nocturnal cleaner, the Gloucestershire senior installed a night-time camera. He wasn’t quite prepared for what he captured. One night, a mouse climbed out of the box. The rodent then proceeded to pick up and carry nail clippers, screws, and a metal chain, depositing each item back inside the box.
At first glance, it might appear odd that a mouse is obsessing over metal bits and bobs. But these rodents have strong instincts for organizing their environments, hoarding, and even cleaning around them, so it’s likely that one or more of these urges drove this mouse to pick up after the man.
6 Some Mice Recognize Themselves
Researchers use the “mirror test” to determine if a specific animal can show a higher degree of thinking by recognizing themselves in a mirror. The method is simple. First, a mark is placed on an animal’s forehead. If the creature looks at a mirror, sees its reflection and the mark, and then touches its own forehead (not the mirror version), it proves that the animal is aware that it’s looking at itself in the mirror.
Only a few animals have passed this intelligence test, including some primates, elephants, and dolphins. The latter could not touch their foreheads, but as soon as researchers marked their heads, they would race to an underwater mirror to look at themselves and investigate the mark.
In 2023, researchers reported that mice appear to have passed the coveted mirror test. After splotching white ink on the foreheads of black mice, the rodents spend more time sitting in front of the mirror and grooming their heads, presumably to get rid of the ink. Interestingly enough, the mice only showed this behavior if they were used to mirrors or socialized with other mice who looked like them, and the ink mark was large.
5 Mice Living In Mammal Hell
High in the Andes Mountains is a place called Puna de Atacama. It is so hostile and desolate, with barely any oxygen or water, that NASA used the plateau to simulate conditions on Mars. In the 1970s and 1980s, scientists found the mummified bodies of leaf-eared mice (Phyllotis vaccarum), which only reinforced their suspicions that Puna de Atacama was a dead zone for mammals.
They suspected the rodents were accidentally or purposefully taken to the area by Incas, who often headed up the mountain to perform sacrifices. Once there, the animals couldn’t survive and perished. But when scientists recently revisited the arid landscape, a different story emerged—mostly because they started catching live leaf-eared mice.
Apart from discovering healthy rodents at a height no mammal had even been found living, other clues supported the idea that the mice were long-time residents that raised families on the mountains and never hitched a ride with the Incas. Some of the mummified mice were close relatives, and there were also mice burrows. However, it’s still unclear how they survive or why they prefer to live there.
4 House Mice with a Horrifying Taste
Mus musculus is a common house mouse all around the world. To homeowners’ dismay, they nibble on everything in the pantry. But for researchers on Gough Island, in the South Atlantic, their experience with this rodent took a sharp left into the realm of horror.
On this island, the mice are huge. An ordinary house mouse weighs 0.7 ounces (19 grams). But on Gough, the rodents are often twice the size and can grow to 1.8 ounces (51 grams), making them the heaviest and biggest mice in existence. And they’re not just fat. Their bone structure is bigger than that of house mice living elsewhere.
One reason why these mice are so hefty could be because they have no predators or competition for food. And their food of choice is stomach-turning.
The rodents have developed a taste for baby seabirds, often eating them alive in their nests. Researchers have noticed that this gruesome behavior is not only fueling the size of the mice but also pushing some of the bird species toward extinction.
3 Melodious Mice
In the cloud forests of Central America, there is a rodent called Alston’s singing mouse. This is not a whimsical name. They really do sing. When romance is in the air, males will court females by squeaking tunes, often in tones that are inaudible to humans.
But what caught the attention of researchers is the audible “conversational” songs that occur between male mice. The chatter is fast-paced and oddly polite. While one mouse “sings,” the other one will stay quiet. Once the singer falls quiet, his companion almost instantly responds with his own song. These back-and-forth musicals revealed that the mice can communicate using almost 100 different notes.
2 This Mouse Turns Venom into Painkillers
The bark scorpion is the most poisonous scorpion in North America. Its sting is incredibly painful, and children and vulnerable adults can develop seizure-like symptoms and paralysis. They even risk death. Even healthy adults can develop breathing problems. Compared to how humans are affected, small mice should die shortly after being stung.
However, when the grasshopper mouse gets stung, it doesn’t expire. Measuring just 4 inches (10 cm) long, the rodent’s reaction to being injected with the deadly venom is unusually blasé. It might jump away at first and then either groom itself or turn the scorpion into a hearty meal.
The mouse is not just immune to the bark scorpion; they experience its venom as a painkiller. Once the toxin is inside their bodies, certain proteins attach to the venom molecules, rendering them unable to cause physical agony. This reaction numbs the mouse’s entire pain transmission system, which temporarily prevents them from feeling any pain, not just those related to the scorpion sting and venom.
1 Mice That Grow New Tails
Some amphibians, like salamanders and newts, are not bothered when they lose a limb or tail. They just regrow them. The ability to regenerate body parts is not something one might associate with mammals, but that doesn’t stop the African spiny mouse from displaying similar healing powers.
This tiny miracle not only regrows tails but can also seal tears in their ears and generate new skin, nerves, muscles, and even toe tips—all without leaving scars. To achieve this feat, the mice rely on immature cells that are similar to those found in newts and salamanders. These cells can turn into different tissues as needed, repairing missing skin, toes, or wherever the wound may be.