How Big Do Rats Get?

As a 30 year plus veteran of rat trapping, I always get a kick out of people wanting to confirmation that the rat I caught at their home was “the biggest rat you’ve ever seen?” I’ve seen lots of rats in my time, thousands in fact. But are there really cat sized rats running all over town?

The simple answer is, it depends. I know, it sounds like a wishy-washy answer so let me explain. While there are the two most common rats, roof rats (Rattus rattus) and the slightly larger Norway Rat (Rattus norgevicus), in certain regions you will find the much larger Gambian pouched rat (Cricetomys gambianus).

The species of rat is part of the equation but it is not by any means all of the equation. There are are few factors to consider when searching for the elusive…(or possibly common?). Follow me and let’s explore the secret world of the giant rat.

When it comes to size, rats are very similar to people. Some are big, some are small but on average, they are all pretty much the same size. Yes, there are exceptions but when averaged out over literally billions, the few anomalies are not large enough to register. Rodents make up the largest population of animals in the world, in fact they are one-third of all mammals on Earth; and they are all pretty much the same size, within their specific species.

It would be easy to discuss a wide variety of rats or even rodents in general from all over the world to support the case that there are rats the size of cats running everywhere.

We could talk about giant cloud rats(Phloeomys pallidus) or the Alpine wooly rat (Mallomys gunung). Then there are the giant extinct rats found in East Timbor, Indonesia.

And if we go down that road, we can argue that nutria, beaver and capybara are nothing but giant rats. While they are giant rodents, they are not giant rats and they are not part of the answer to the question you are really asking, which I believe is really “Do we have rats the size of dogs running around where I live like I hear about?”

The most famous specific statement goes something like “In New York City we have rats the size of cats!” Occasionally “cats” is replayed with “dogs”, but you get the point. New York is the common city but it works in Chicago, Baltimore and it even works where I live in the Tampa Bay Florida Area where our most common rat is the roof rat, the smaller relative of the larger Norway rat.

Misidentification Of Rats

Misidentification is common when claiming “giant rats, the size of cats!” After all I have seen, I am sure that in a few cases, people are actually seeing rats. Perhaps in the dark, maybe after a couple libations if is easier to confuse a rat and a cat.

What I do know is that people have misidentified opossums for rats. People often mistakenly call opossums “nothing but giant rats” ) which could not be further from the truth), in poor lighting to an untrained eye, I can understand how people can make the mistake. I have actually witnessed this as part of my job as a professional rat trapper (with an affinity for opossums).

It seems funny that people could mistake a cat or opossum for a rat but I go back to my youth when I mistook what must have been nighthawk or a similar bird with giant bats. For years I would tell of these massive bats that would fly around our soccer field at dusk.

It was only in my late teens that I learned that there are no bats in the United States that achieve the super sized beasts that seemed to dive bomb us as we played soccer. Bats are another one that have legendary size claim, but we will save the for another article.

Forced perspective

The internet rocks at freaking people out with pics of gigantic creatures using forced perspective. Forced perspective was most likely first discovered by fisherman who discovered they could tell even bigger fish tales by holding out their fish so that it is closer to the camera in relation to their body. Forced perspective can make a fish look twice as large as it really is.

Perhaps the first notable case of forced perspective on Facebook what when US soldiers in Iraq were showing pictures of the famed camel spiders. Countless people were duped into believing these monsters were 2 to 4 times larger than actual size. Don’t get me wrong, they are huge, but this is a clear practice of forced perspective.

These pictures are all over the internet using fish, alligators, crocodiles, snakes and yes, there is even a epic, giant pig.

A picture is worth a thousand words but it still does not make it true. Rats too, fall prey to forced perspective.

It is not foolproof, however the best way to check for forced perspective is to see if the subject of the photo is up against something of measurement. Is it on the ground with a shoe next to it? Is being held against someone’s body? Or is it being help out, toward the camera? Is the camera angle show from below as to make the subject look larger?

People See What They Want To See

Going back to my youth with me seeing “bats” rather than the nighthawks which they really were, often times, people see what they want to see and it makes a far better story to tell someone that you are dive bombed my giant bats rather than just birds flying around eating bugs.

I’m confident “People see what they want to see” is the most accurate answer to the question. It is not only exclusive to rats. I have been a nuisance wildlife trapper for more than 30 years and for whatever reason, people want to believe that whatever animal they have is the biggest animal in the history of that animal.

After catching an animal, without question the most common question we get is “Is it big?” or “Is it the biggest one you have ever seen?”. With the exception of a raccoon I caught in Illinois in the 90’s, I have no recollection of any animal, regardless of the species being abnormally larger than any of the others. And the raccoon? It was big but not big enough that scientists need to be notified. It was just fat.

There are many animals in the the Northern United States that are smaller in the Southern United States. Examples are squirrels, deer, raccoons, blue jays and yes, rats.

Animals in the North need to deal with harsh winters and their bodies are made to quickly put on weight and as such, they are larger.

No doubt there are some giant rodents running around the big rock we all live on. Some bigger than others but by in large (no pun intended), they are all the same size in relation to their species. Yes, a capybara is larger than a house mouse, but you are not going to find a house mouse the size of a capybara!

I have found that generally people  find it easier to cope with having mice rather than having rats. I was a nuisance wildlife trapper in Northern Illinois in the very early 1990’s. In the Winter, mouse calls were common. However, we never, ever had any rat calls.

When I move to the Tampa Bay Area and started my own business I got a call for an animal in an attic. After an inspection, I found the lady had rats. It was a nice home and I though she we throw me out if I told her she had rats. I timidly told her the issue and expected to boot out the door. Instead, she said “Oh, I figured! We’ve had them for years.”. It was at that point that I learned that rats are incredibly common in some parts.

Regardless, I still get the occasional person that refuses to believe they have rats and insists on calling them mice. The call normally goes something like this:”

Dusty: Hello, Creepy Creatures. May I help you?

Caller: Hello, I think I have mice.

Dusty: You most likely have rats.

Caller: No, they are little.

Dusty: Those are baby rats.

There is a mental block with having rats. It’s easier to think they are mice rather than baby rats.

People either want to have the biggest rats in the world…or they want to believe they have mice. There is very little grey area.

I’d just like to assure you, with the right program you have be rat…and mouse free.

[Related Questions]

Where do rats come from?

Going back to the beginning, Norway and roof rats came over on ships of the early settlers. They both competed for food on the ships and often became the food as food on long ship voyages became sparse.

Our customers always have suggestions as to where their rats from:

  • We live near the water
  • Our neighbors just did some construction
  • We have an orange tree
  • We live near the woods
  • We live near a swamp
  • We live near whatever…
  • Our neighbors are pigs.

You get the point. The fact is that if you have rats living in your region of the country, you probably have rats near you.

I tell people “We have rats everywhere, in every neighborhood.” Some people challenge with “No, I do not see them in our neighborhood.” That is because rats are active at night and you are very unlikely to see them.

Where do rats nest?

Rats are well settled and will readily live wherever there are people. Rats need food, water and shelter. Rats will live in tunnels underground, sewers, storm drains, sheds, walls and attics.

As we discussed earlier, Norway rats do not readily climb and roof rats are excellent climbers. It is common to find Norway rats in tunnels, walls and messes where they can make a nest.

Roof rats will live underground and we have cases of them using the sewers to enter attics and toilets; their favorite home though is up in an attic.

The better you are at eliminating all three, the more likely it is you will not have rats.

Do rats hibernate?

No, rats do not hibernate. Depending on their region, their activity can change. Many rats will hoard food, stockpiling things like acorns and anything else they think may have value.

It is possible to find larger rats toward the end of the Summer as they have been gorging themselves with abundant food. But again, these are commensal rodents and they seek to be around people. Living around people means food and shelter is typically more available and they are not as reliant on the seasons to bring them a plentiful bounty.

Dusty Showers has been in the urban nuisance wildlife and pest control field since 1993. Taught by Garon Fyffe, a pioneer in humane nuisance wildlife management, Dusty has a passion for finding humane solutions to human & wildlife conflicts. Dusty was the only individual invited by the Florida Fish & Wildlife Commission in the lat 1990's to help write legislation for legal protection of Florida bats. With an instinct for solving wildlife, Dusty found pest control to be an easy "add-on interest". Dusty started his first business "Animal Instincts Wildlife & Pest Management" in the Tampa Bay, Florida area in 1995. Eventually selling Animal Instincts in 2002, Dusty went on to start Creepy Creatures Termite and Pest Control in 2009, which he still owns and operates today in Palm Harbor, Florida.


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