Rats can be a real problem no matter where they congregate, but in barns they can be worse than a nuisance. Rats and the fleas that live on them can easily carry and transmit diseases to your livestock. A barn is a prime place for rats to get food, since livestock feed usually contains grains, a favorite rat treat. Also, the hay bales that are often stored in outbuildings are perfect for barn rats to nest in.
Buy a Rat Terrier
One of the best ways to kill barn rats is to buy a rat terrier. Rat terriers are dogs that were bred in Great Britain for the single purpose of killing rats and other rodents and vermin. Because they have such high energy and have been bred to kill vermin, a rat terrier will clear your barn of rats quickly and easily. The dog will prevent further infestations in the future by killing any new rats that try to move into your barn. Rat terriers have the added advantage of being good pets for both children and adults.
Use Snap Traps
If you can't adopt a rat terrier to clean out your barn, another option is the snap trap. For this method to be effective, place snap traps anywhere you see rat urine stains and feces, near places where wood has been gnawed, and in any spot that has obvious signs of rat activity. Bait each trap with both gauze and a food item that a rat will find irresistible, such as peanut butter or a gumdrop. The gauze will trap the rat's teeth and prevent it from escaping before the trap is triggered. Tie the gauze into the trigger with thread to hold it there. Be sure to anchor the trap in some way so that the rat cannot drag it away if the trap does not cause an immediate fatal injury.
Set Up Nesting Boxes for Owls
Barn and screech owls are natural enemies of rats and other rodents. If you build nesting boxes of the proper proportions, barn owls and screech owls will be encouraged to nest in the area near your home and barn. Owls will kill many rats to feed their growing families, so having them near your barn can be very beneficial in controlling rats. Websites such as Owlcam.com provide instructions for building owl nesting boxes, or you can purchase a pre-made owl nesting box.
Be Cautious About Poison
While poison is an option for killing rats in a barn, it is not recommended for use in a barn setting. Rodenticides are known as secondary poisons. This means that any predatory animals, such as owls, hawks or even one of your barn cats that eats a dead rat killed by poison will be poisoned as well. There is no safe rat poison, according to wildlife protection organizations such as The Hungry Owl Project.
One of the ingredients in the most popular rat poisons is an anti-coagulant called brodifacoum that is a powerful secondary poison. A study performed by the Wildlife Pathology Unit of the New York State Department of Environment Conservation found that out of 51 cases in which wildlife was killed by poison, 80 percent of the animals died due to secondary poisoning by brodifacoum. Using rat poison against rats in a barn puts beloved pets and even family members at risk of accidental poisoning. Finally, rat poison can take several days to actually kill a rat, and in that time the animal may hide in an out-of-the-way spot, such as under a porch or inside a wall. If it dies there, its body will cause contamination and a horrible smell.