Rat kings might actually be real—but it's nothing to laugh about

National Geographic

2 days ago

A rat king displayed at the University of Tartu Natural History Museum in Estonia. Some have claimed that the phenomenon in which rats become entangled by their tails is just a hoax but experts say there's reason to believe it's real. Photograph by Oleksandr Rupeta, Alamy Stock Photo
This phenomenon is when a pack of rats become entangled by their tails, unable to separate themselves. We asked experts to weigh in on whether it is really possible.
Since at least the 1500s, people have been mesmerized by the legend of a so-called 'rat king.'
Usually depicted as a mass of a rodents with their tails tied in a knot, the specific details can vary by the telling. In some stories, the group is led by one rat that directs the rest, perhaps with psychological powers, while in others, the whole group works together, like some kind of amalgamated monster.
In one version or another, the rat king—which can refer to the whole group of animals, or simply the dominant rat—is an idea that has appeared in all forms of pop culture.
But is there any truth to the rat king legend?
Some experts have argued that historical rat king 'discoveries' could have been hoaxes—although they couldn't rule out the possibility that such a thing is physically possible. Meanwhile others are convinced.
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'The rat king is not a legend,' argues Andrei Miljutin, curator at the University of Tartu Natural History Museum in Estonia, in an email. 'In contrast to gods and humanoids, everyone can see and study rat kings at museums in different countries. Two of them are housed in the very building where I am writing this message.'
However, Miljutin, who says rats are his favorite animal and that he somewhat fell into studying rat kings, stresses that the discovery of one is nothing to celebrate.
'Indeed, it is a death sentence. The animals suffer from permanent pain. They cannot move around normally to find food and water, and what is worse, they are helpless,' he says. As rats scramble over one another, their tails can become entangled. Above, a miniature sculpture by 19th century netsuke artist Ikkan depicts five rats in a ball. Photograph by Heritage Art/An illustration of a rat king drawn by German physician M. B. Valentini in 1714. Tales of rat kings date back at least to the 1500s. Photograph by Interfoto/Alamy Stock Photo
In a 2007 study published in the journal Proceedings of the Estonian Academy of Sciences, Miljutin found that, before 2005, there were 58 rat king sightings he deemed reliable, though just six of these were preserved in museums. Interestingly, some common themes emerged.
With the exception of one rat king documented on the island of Java in Indonesia, all the rat kings were from the same species—the black rat, or Rattus rattus. Most were identified in Germany, France, Poland, the Netherlands, and Belgium, and findings often seemed to coincide with spates of cold weather.
(Carolina the giant rat retires as a hero after saving many lives.)
Therefore, Miljutin concluded that rat kings are most likely to occur in areas where both cold winters and black rats are found.
As for how the tails of the rats became entangled, it seems true rat kings are not a result of knotting, but rather the product of some other sticky material.
In one case Miljutin investigated in South Estonia in 2021, he says, 'the knot of tails looked like a large ball due to the incorporation of a mixture of clay soil, poultry manure, straw, and feathers.'
Interestingly, those rats were still alive by the time Miljutin got to them. This makes him one of the very few people known to have seen a living rat king phenomenon in person.
The local news channel even captured video of the 13 tangled-up black rats—all young rats of both sexes. How rat kings could happen
As an urban rodentologist of more than 30 years—who has even been described as 'the rat king of New York' himself—Bobby Corrigan has come across this legend more than once.
'I have been asked in the press multiple times about rat kings, and I always reply I have not personally witnessed it in my long career,' says Corrigan, who spent 16 years teaching at Purdue University and is now a consultant for RmC Pest Management Consulting.
But after reviewing Miljutin's evidence, Corrigan says he's convinced.
'For sure, it is real, but it is rare,' he says, 'or at least rare to us humans. Maybe not to the long-tailed rats of the world.'
(Is it time to finally ban glue traps in the U.S.?)
There are also several aspects of rodent behavior and anatomy Corrigan has seen firsthand that align with what would be necessary to create a rat king.
'Rats have a behavior where they all get together in very tiny spaces in walls and ground burrows. It's called hugger-muggering,' says Corrigan. 'They all get really close together to exchange body heat, because they don't hibernate.'
Similarly, Corrigan says rat tails are composed of cartilage, which makes them very flexible, and many rat species use their tails to curl around branches to provide some extra grip.
However, rat tails cannot be tied into a knot, he says.
Finally, while he finds it unlikely any trapped rodents would obey a master and function as one, rats do establish hierarchies, similar to primates or canines.
'Often there will be a dominant male that mates with all the females and keeps a territory,' says Corrigan. 'So, is there a dominant rat in the area where there is a social structure, and could you call that rat 'king'? Yes.'
While rats and rat kings might seem frightening—especially as they're portrayed in pop culture—Corrigan says he takes a different point of view.
'We probably owe 20, maybe 30, additional years to our own [life expectancy] to rats,' he says. 'We've tested every single cancer drug in the world on them, every pharmaceutical, and we continue to do so.'
'These animals are a tremendous benefit to humankind,' says Corrigan.