Rats can cause some major damage in chicken coops. Credit: Mary Altaffer / AP

Vermin — rats included — are a fact of life on farms. Outbuildings, barns, poultry coops and storage areas have everything a rodent needs for shelter and food. If you are not careful, according to state pest experts, you may find yourself with a rat infestation on your hands.

While it’s impossible to prevent every rat from visiting your farm, there are things you can do to prevent the rat population from exploding. Here are a few things you can do to make your farm less attractive to all vermin.

Rats in Maine

The most common rat in Maine is the Norway rat, according to Griffin Dill, pest management professional with the University of Maine Cooperative Extension. It’s an invasive species that arrived here hundreds of years ago on ships from Asia and Europe. Norway rats live in large family groups and that can be bad news for anyone dealing with them.

“When you see one, there are likely to be more around,” Dill said. “Just because you only see one running across your yard or in the coop does not mean there are not dozens more on your farm.”

Try as he might, Dill can’t come up with any redeeming quality of a Norway rat. Not only will rats eat the chicken food, eggs and chicks, they are also carriers of diseases like rabies, salmonella, leptospirosis and hantavirus, which can all be transmitted to humans.

“I never wish harm on any creature,” Dill said. “But rats are reservoirs of disease and one of those things that can cause a lot of devastation in the settings they inhabit.”

Rats follow the food

Once a rat or colony of rats discovers the available food and shelter on a property, they will move in, according to Kathy Murray, entomologist and integrated pest management specialist with the Maine Department of Agriculture, Conservation and Forestry. Improperly or carelessly stored chicken feed will attract rats who are also more than happy to drink any water put out for chickens.

“If you are going to have a backyard flock or any animals you need to take steps to prevent attracting any kind of wildlife,” Murray said. “Rats like people and they like our food and when we have backyard animals we are providing food for them.”

As for shelter, any old straw, wood shaving, chips or other chicken bedding that is simply tossed into an open air compost area makes a perfect place for rats to burrow and nest, as does the space under a chicken coop.

Rats, Murray said, are part of the Maine wildlife population but are also a commensal species. In a commensal relationship one species — in this case rats — benefits from the associating with another species — in this case humans. Rats are opportunist scavengers that are more than happy to live off food thrown out by humans or stored in unsecured locations.

What to do if you see rats

The bad news is that once they take up residence rats can be extremely difficult to eradicate, but there are some steps you can take to help reduce their population.

Trapping is among the best ways to try to rid yourself of a rat infestation, Dill said. He is a fan of the simple, large wood-based snap trap you can get at most hardware or farm supply stores. Traps should be placed next to walls, behind objects, in dark corners or anyplace that has evidence of rat activity such as chewed wood or droppings. Check your traps daily and safely dispose of any dead rodents.

Some rats become “trap shy” once they see a fellow rat caught or have their own close call with a trap.To help avoid this, place some bait such as peanut butter on an unset trap and let the rats get used to it being a source of food.

Wire cage “no kill” traps are also effective in catching rats, but leave you with the problem of what to do with the live rats. One option is to take them far away and release them, but that can create problems for other homes. The alternative is humanely killing the rats yourself once they are live trapped.

Poison in various rat-killing formulas are available from garden supply stores, hardware stores and farm supply stores. It can be successful in reducing your rat population but you also run the risk of curious pets or livestock ingesting some by accident. The safest option is getting poison pre-packaged in small packets you can tuck out of reach of your pets and other animals.

Rats are attracted to these packets and will chew through the packaging to get at the poisoned bait.

Sound or electronic devices marketed as rat deterrents have very little success, according to information from the University of Maine Cooperative Extension. Rats quickly become used to new noises and will ignore them.

How to prevent rats in the first place

The best plan, Dill said, is to avoid having the problem at all. That means taking steps to make the farm unfavorable to rats before they even consider taking up residence.

“The biggest things are exclusion and sanitation,” Dill said. “You want to limit the food sources available to rats and eliminate the ways they can get into coops.”

Chicken feed should not be broadcast randomly and left for the birds to peck. Rather, it should be stored in secure, metal containers and fed to the chickens in amounts they can consume fully over the course of a day.

“It comes down to sealing up food so the rats don’t have access,” Murray said. “Rats love chicken food and they love chicken manure because it is full of undigested food.”

Picking up trash, brush and even large tools takes away places rats can hide behind or burrow under. Keeping grass trimmed and mowed can also help.

Dill recommends raising chicken coops off the ground so rats have nothing to burrow under or placing it on a cement slab. Since most coops are made from wood, which rats can easily gnaw through, Dill admits excluding them can be a challenge.

Using metal wherever possible, from coop construction to food storage, is the best bet according to Murray, as rats can’t gnaw through it.

“There are definitely ways to manage rats,” Murray said. “But it’s really all about managing ourselves and the stuff we make available to them via our chickens coops and garbage.”

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.