Biology of Rats and Mice
You might have a bit of a snide reaction when someone tells you that it is important to understand the pests commonly found in homes across the country. We want to make it clear that by “understanding” we don’t mean sitting down and trying to appreciate the way the rats that have infested your house scurry from corner to corner, terrifying your children, harassing your pets, eating your food, creating a health hazard, and pooping everywhere. What we mean is the understanding that is fundamental to integrated pest management; that is, possessing a knowledge of common pests that makes it much easier to deal with them.
By knowing the breeding habits, preferred living spaces, and natural requirements of common pests, we can be much more effective when it comes to controlling their numbers. In this article, we will take a look at the biology of rats and mice.
Rats and mice
Rats and mice sit at number two and number three as the world’s most successful species of mammal, coming right after humans (which is kind of depressing if you think too hard about it). The key to their success lies both in their adaptability and in their ability to breed like, well, mice and rats; we will get to that more in a minute.
Obviously there are many different species of both mice and rats, and we will get into the specific animals in just a minute, but first we might as well go over what the two animals have in common.
Both mice and rats are rodents, a group of small herbivorous animals (although rats have been known to eat carrion) which posses large teeth, useful for chewing just about anything. Mice and rats have been found to have incredible survival skills, making themselves right at home in any area where humans can live. Both are known to be causes of several diseases (more on that in another article), and both lie towards the bottom of the vertebrate food chain.
Some differences
The mouse that is most often encountered by humans, as a pest, is the common house mouse. These little guys have been with us for probably as long as we have existed. They are one of the most helpless animals there are, but their breeding capacity ensures that there will never be a shortage of mice. In fact, with perfect conditions the numbers of mice can increase to absolutely horrific levels. Female mice reach sexual maturity at just under two months, after which she may give birth to six babies every month or so. That means that with generational considerations, one mouse could have 8,000 descendants in one year!
There are two different species of rat that are common house pests. The larger of the two is the Norway rat; it’s this rat that can grow to huge sizes, sometimes as big as a cat, if living under the right conditions. The other rat is known as the roof rat, not quite as big and creepy, but still a pest. Rats don’t breed as frequently as mice, but that’s not saying much: they still may have anywhere from three to four litters each year, the average size being seven young. Rats are also smarter than mice, which makes them a lot harder to control.