A Look at the House Mouse

As a home or business owner, a person needs to be proactive in preventing a rodent infestation. Because of the ubiquitous nature of the house mouse, a residential or commercial property owner needs to have a basic understanding of the essential facts associated with the house mouse.

Physical Appearance of a House Mouse

The wild derivation of the house mouse – the type of house mouse that hasn’t been domesticated – has light brown to gray or black fur on the tops of their bodies. They have lighter colored or white bellies. (The domestication of house mice is discussed shortly. This has resulted in an array of different fur colorations not found in the wild.)

The tails of house mice don’t have much hair. They are nearly bare.

An adult house mouse can grow up to 20 centimeters from the tip of the nose to the end of the tail. An adult house mouse weighs about 12 to 30 grams.

The Long-Standing Connection Between the House Mouse and Humans

The house mouse is the species of a rodent that has been most often domesticated. The house mouse was domesticated at what today is known as the fancy or pet mouse. Indeed, the fancy mouse is one of the more popular pets after cats and dogs in the United States and in some other nations as well.

In addition to being the type of mouse that was domesticated as a pet, the house mouse was also domesticated for laboratory use. In fact, the house mouse is now considered one of the most important organisms utilized in medical and biological research. In fact, the house mouse was the species that the entire mouse reference genome was sequenced in 2002.

Social Behavior of House Mice

The manner in which house mice socially organize and behave depends on where they live. House mice socially organize depending on whether they live within a closed environment, like a house or some other structure, or reside in the open, such as in open areas out of doors.

When house mice reside in a home, business, or similar structure, their populations will increase, and usually fairly rapidly. This occurs because house mice in this type of situation have adequate shelter and typically easier access to food. Thus, these mouse populations are not under as intense pressure for adequate shelter and food.

When a house mouse population is established in a house or similar situation, the mice social structure becomes that of a hierarchy. These are called commensal populations.

On the other hand, when house mice reside out of doors in more open spaces, they have smaller populations spread out over larger territories. In these settings, house mice are focused more significantly on foraging for food and finding appropriate shelter. Finding food and shelter both become a more significant challenge in this type of setting. 

A social hierarchy does not develop when house mice live out of doors. In addition, house mice tend to be more aggressive with each other when living out of doors because of limitations on resources. These are called noncommensal populations.

Lifespan of a House Mouse

A house mouse is born blind and hairless. Fur begins to grow at about six days to a week. Eyes open at about 12 to 13 days after birth. Pups are weaned at approximately 21 days.

Female mice reach sexual maturity at about six weeks of age. Males reach sexual maturity at about eight weeks.

A house mouse living outside has an average life span of just under a year. When a house mouse is able to live in a sheltered environment, the average life span increases to between one to two years. A fancy or pet mouse, the domesticate derivation of the house mouse, has an average lifespan of between two to three years.

Reproductive Cycle of House Mice

There also exists a variation in the reproductive cycle of house mice depending on whether they live in more crowded conditions in a residence or other structure or if they live out of doors. A female house mouse that lives outside in a less populated area will go into estrus on a regular cycle. However, if a female house mouse lives in a crowded setting, she will go into estrus only when she smells a male’s urine.

The gestation period for a house mouse is between 19 to 21 days. A house mouse gives birth to litters between 3 to 14 offspring. The average number of pups in an individual litter is between 6 to 8.

A house mouse can have an average of 5 to 10 litters a year. House mice residing out of doors will have fewer litters because they will not breed during colder months of the year. In a sheltered environment, house mice will breed year round and have more litters as a result.

Dangers of House Mice and Their Droppings

House mouse droppings can be dangerous. Viruses and bacteria can be spread through house mouse droppings that can cause different diseases, including salmonella. House mouse urine can also carry viruses and bacteria.

Salmonella provides a prime example of why house mouse droppings (and urine) can be dangerous. Their droppings and urine can contaminate food items and beverages. This is a prime way in which humans contract salmonella poisoning, also commonly referred to as food poisoning.

House mouse droppings are rod-shaped and are pointed on each end. They are dark in color when fresh and gradually turn a more grayish hue as the dry out.

Preventing a House Mice Infestation

There are a number of important steps that you can take to prevent a mouse house infestation in a home or business. First, you need to make sure any exterior holes or cracks are plugged to prevent entry into the premises. You need to bear in mind that a house mouse is capable of slipping through a hole that is no larger than a dime.

Second, make sure garbage containers inside and outside of a house or business are tightly sealed. The same holds true for food packages in a residence as well. House mice are attracted to residences not only because of the shelter provided but also because of available food. On a related note, don’t leave pet bowls containing food sitting around for extended periods of time.

Third, eliminate any water pooling in or near a building. Water also attracts house mice.

Fourth, keep vegetation – particularly shrubs, bushes, and the lawn – well tended. Do not allow these types of vegetation to become overgrown.

Keep vegetation away from being directly next to a building. Consider placing an 18-inch to 24-inch gravel parameter around the perimeter of a building. This creates a “no-mouse perimeter” that house mice will hesitate crossing.