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Can roof rats be released outdoors in winter? #382165 - Ask Extension


Can roof rats be released outdoors in winter? #382165

Asked January 16, 2017, 3:22 PM EST

A building I work in has recently been invaded by what I believe are roof rats. It's an ancient building. Holes in the ceilings allow the rats to come down from the unfinished attic into main the building at night, so they occasionally get into trash if we forget and leave food trash in a trash can.  The business owners are not willing to do the necessary structural work to exclude the rats but are threatening to trap and kill them. I've told them that my job description does not include slaughtering small animals, but if they live trap, I will take charge of releasing any rats they trap. The problem is, it's the dead of winter and these rats are obviously adjusted to living in the attic.Outdoor rats make preparations for winter, which these rats wouldn't have done. Is it safe to release them away from human habitation at this point, or do I need to wait until spring and begin trapping them when the weather is warmer?

Kittitas County Washington

Expert Response

Hello, This would be a good time of year to eliminate the rats, before breeding season picks up again. Exclusion is the only way to solve rat problems. If you are able to trap all the resident rats, new populations will likely colonize the habitat.

Live trapping is not recommended due to the following reasons:

“Live traps: Live traps are not recommended because trapped rats must either be killed or released elsewhere. Releasing rats outdoors is not recommended because of health concerns to people and the damage they may cause elsewhere. Because neither the roof nor Norway rat is native to this country, their presence in the wild is very detrimental to native ecosystems. They have been known to decimate some bird populations.”

Additionally, live trapping may require a significant amount of your time depending on the size of population.

If you do choose to release them, you can do so anytime during winter. Rats are highly adaptable. You must however consider an appropriate location. Rats are not only detrimental to human habits, they are highly destructive to wildlife and cause damage to natural habitats.

To learn more about rats and rat management, visit:

Todd Murray Replied January 17, 2017, 12:36 PM EST
Thanks Todd! Your assurance about the winter conditions is exactly what I needed to know. WS
The Question Asker Replied January 17, 2017, 1:24 PM EST
Ticket closed
Todd Murray Replied January 23, 2017, 11:39 AM EST

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