In the battle to control rats, it is helpful to understand all aspects of their behavior, including what they eat. Once you understand what they eat, how they eat, and why they consume certain things, you can be better prepared to figure out how to get rid of them.
So let’s find out the answer to the question, “What do rats eat?”
Rats Are Omnivores
Rats are omnivores that will eat just about anything. This makes them especially difficult to control, as they can often find food sources in very creative places. It’s not unheard of for rats to feast on such delicacies as wet sawdust, discarded plastic food containers, and even moldy fabric!
As hardy as rats are, they do have some dietary preferences. After all, a rat is a vertebrate animal that needs basic nutritional substances to survive (think basic protein and essential minerals). In the wild, rats will typically eat any and all of the following if it is available to them:
- Disposed food scraps
- Dead or dying root vegetables like carrots or potatoes
- Mushrooms and mushroom mycelium
- Expired carcasses of other animals
- Composting material
- Rotten fruit
- Virtually anything organic with any nutritional value whatsoever
When we look closer at the different species of rats, we find that different rats eat different things. In the United States, there are two species of rat that are most common: the Black Rat and the Norway Rat.
Let’s take a look at the differences in diet between these two rat species.
Diets of Black Rats (Rattus rattus)
Black Rats, also known as the ‘ship rat’, the ‘roof rat’, or the ‘palm rat’, primarily eats grains and seeds. The reason for this is because this food source provides the rat with stored energy that can sustain them through long periods of food shortage.
Their affinity for grains and seeds makes Black Rats a serious threat to agriculture. Because Black Rats can nest in trees, gutters, wood piles, and even underground, they can often simply set up shop near a significant food source (say, a grain silo) and breed even more rats.
In a pinch, Black Rats will eat insects within their vicinity, but it’s important to note that these rats are not hunters. So, you don’t have to worry about a Black Rat making lunch out of your pet gerbil.
Diets of Norway Rats (Rattus norvegicus)
Like Black Rats, Norway Rats (also known as sewer rats)are true omnivores that will eat just about anything composed out of an organic substance. However, given the choice, a Norway Rat will almost always prefer meat above other food sources. And, they’ll even hunt for it.
Some of the most common animals that are preyed upon by Norway Rats include:
- Chicks
- Mice
- Birds
- Small lizards
- Fish (some Norway Rats will even catch fish with their bare paws!)
- Mollusks
- Worms
Remember that a small animal doesn’t have to be alive for it to be considered a meal by a Norway Rat. A dead meal is still a meal, in their eyes. Another interesting dietary fact about the Norway Rat is that it’s not too proud to eat fungii or slime molds.
To a Norway Rat, if it looks like food, smells like food, and if it probably won’t kill them, they’ll eat it.
Both Norway and Black Rats Need to Eat Their Poop
Another important aspect of how Black Rats and Norway Rats survive has to do with something called coprophagy, a term used to describe the consumption of fecal matter. That’s right: these species of rat eat their own feces.
Why? Because they have to, in order to survive.
You see, rats have highly developed ‘hind guts’, which is just another way of referring to a rat’s large intestine. This section of the rat’s gastrointestinal tract is especially good at helping to ferment plant-based solids, releasing amino acids in the process.
In order for the rat to get the benefit of this fermentation process, it has to consume the already-digested material again. So, not only do rats eat the waste of humans, they also dine on their own excretions.
Rats Eat Large Quantities of Food Every Day
Both the Norway Rat and the Black Rat have voracious appetites. These animals not only have a broad palette for the food they eat; they also eat a lot of it.
Rats will typically eat around about 5% of their body weight in food every day. For a rat of a typical size and age, this means a food intake of 10-30 grams per day. For some perspective, a teaspoon of sugar weighs about four grams.
If a 200-pound man ate as much as a rat does, he would need to consume a whopping ten pounds of food every day.
Because rats eat so much, their volume of feces is high, as well. This is in-line with the practice of coprophagy mentioned above. It is estimated that a single rat can leave over 25,000 droppings in any given year, with an untold number of those droppings being re-consumed by the rat.
Rats Do Not Trust New Food Sources
Rats didn’t evolve to become the tough, intelligent creatures they are today by being gullible. In fact, most rat species are highly skeptical of new food sources. One common theory for this relates to how often, over thousands of years, humans have tried to kill rats off using poison-tainted food.
The rats have simply adapted, using skepticism as a tool for survival.
So, despite Norway Rats and Black Rats being omnivores that consume great quantities of food, they do not simply dig into just anything they come across. This is a phenomenon among rats known as ‘Poison Shyness’, and it’s a huge reason why rats can be so difficult to control.
Rats Need to Eat Hard Things
A defining characteristic of all rodents, including the Norway Rat and the Black Rat, are the front incisors that never stop growing. All rodents must constantly gnaw on hard material to file down their incisors and keep them sharp.
If this ‘dental maintenance routine’ is neglected for too long, the rat’s teeth can become dull and ineffective. Therefore, rats will often prefer to eat things that are hard or brittle. This often explains why chew marks from rats will show up on wood framing, metal braces, or other hard surfaces.
This also helps to explain why the rats in your attic can be so destructive. They will chew on structural materials including electrical wires and pipe conduit, just to keep their teeth sharpened. This can eventually result in a seriously compromised building substructure.
Rats Drink As Much As They Eat
Not only do rats love to eat, they also love to drink. In order to process all of the food that rats forage for every day, a roughly equal volume of water needs to be consumed. This is important to keep in mind when attempting to control a rat population, because if access to water can be removed, the rats can be further contained.
Also, many rat poisons can be administered in a tasteless, odorless liquid format. Using liquid poisons can be very effective in areas where rats have an abundant supply of food but a limited supply of water (grain storage areas, warehouses, etc). Be aware that the use of liquid rat poisons requires a strict safety protocol to protect humans and other small animals in the same proximity.
Summary and Conclusion
The Black Rat and the Norway Rat represent the vast majority of the rats that populate North America. These species are like many other rat species in that they are omnivores that will eat just about anything.
Controlling these rats involves understanding their diets, which we’ve covered in some detail here. For more information or to inquire about how best to deal with a specific rat control situation, consider the other resources listed on this page.
