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Preventing Mouse Invasions

Preventing Mouse Invasions

What do mice look for when exploring new environments?

 When you first arrive at a new destination, what do you do? Look for a nice, quiet place to relax? Find something to eat or drink? Or dive right in and introduce yourself to the locals? These are some of the questions researchers are answering about house mice and their behaviors when exploring new environments.

“Understanding how mice behave when they are introduced to a new environment helps us develop effective techniques for preventing rodent invasions on islands and other areas,” states NWRC research wildlife biologist Dr. Gary Witmer.

House mice (and rodents in general) have many characteristics that make them effective invaders. They can live in a variety of habitats, are typically small, secretive, nocturnal and have keen senses of touch, taste and smell.  As invasive species, rodents cause serious damage to native plants and animals, agriculture, property, human health, and other resources. On islands, where predators are often lacking, invasive rodents can decimate native plant and seabird populations.

In order to develop better biosecurity methods for detecting and preventing house mice invasions, NWRC researchers conducted a laboratory experiment that simulated an invasion by wild house mice. Wild-caught mice were placed into a radial arm maze with eight arms that represented a novel environment. Researchers monitored and compared the reactions of the mice to various odors and other attractants such as food, shelter, water, and other mice.

“The most common first reaction of the mice was to seek shelter in a den box,” notes Witmer. “Next, the mice became focused on food scents, particularly cheese, bacon grease, almond extract, and peanut butter. We also noticed that female mice focused more on odors from male mice than vice versa.”

Based on these findings, Witmer and others surmise that a secure den box with certain food and mouse odors might entice and hold house mice in a restricted area for a short period. Such methods could be useful in ports of entry or other locations where invading animals may first appear. For more information, please contact

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