Hi Phyllis,

Thank you for contacting the UNH Cooperative Extension Infoline with your question about how to prevent rats from entering your chicken coop.  I talked to a staff member who has raised chickens for fifteen years.  She offered some options but emphasized that she still has rats.  There are no easy solutions.

She suggested that at night you put out traps that are not set in locations where you see rats.  Do this for several days until the rats are comfortable with the traps, and then bait and set the traps.  You should also check that your traps are in good condition.  The staff member said she had never encountered a live rat in a trap.

There is a company that sells contraceptives for rats.  The contraceptive is a pellet in a hot dog like shape.  The contraceptives may help reduce the number of rats.

Rats are attracted to water.  Is water easily available for them?  Perhaps eliminating a water source would help.

Another use of water is to fill a tall container with water and have a ramp to the top where the rat would fall into the water and drown while trying to get a drink.

Do you have other sources of food or items that attract rats?  The staff member has a compost pile which attracts rats but keeps it because she wants to compost.  If you can ascertain if the rats are attracted to something else and can eliminate, it may help with the rat problem.

Finally, there are companies that have rat terriers that can dig out rat tunnels.  The staff member thought this would make a mess but offered it as another possible solution.

I have also included links to a few fact sheets that discuss the problem.

https://boulder.extension.colostate.edu/wp-content/uploads/sites/7/2020/04/Poultry-brochure-2020.pdf  On page 11 of this fact sheet there are some suggestions for protecting your flock from predators.

https://wildlife.unl.edu/pdfs/rodent-proof-consturction-structural.pdf

https://extension.okstate.edu/fact-sheets/rodent-control-in-the-poultry-house.html

http://extension.msstate.edu/publications/controlling-rodents-the-poultry-farm