Whether you raise poultry for market or maintain a backyard flock, chicken coops are a magnet for rats and mice.
Rats often appear in the fall, when their external food sources are depleted by harvest. They emerge from the fields, where they live in burrows, to forage and feed around buildings. In contrast, mice will establish colonies within buildings and might never venture outside.
Rodents are responsible for more than a quarter of all farm fires of unknown origin, but the main risk from infestations is feed contamination and disease exposure to both you and your flock. A rat can produce more than 40 droppings per day and a gallon or more of urine per year, while a single mouse can produce more than 80 droppings per day and more than a quart of urine per year. A variety of human and livestock diseases are spread through contact with rodent excrement, which include cryptosporidiosis, toxoplasmosis, leptospirosis, brucellosis and salmonellosis.
Rats can also become predatory, killing and feeding on adult chickens, but they can be especially hard on young chicks. As a professional wildlife control operator and hobby farmer for years, I’ve personally witnessed rat infestations that consumed hundreds of day-old chicks within a couple nights. Because rodents are mainly nocturnal feeders, it’s easy to seriously underestimate their numbers and impact on your coop.
Here are a few steps you can take to help minimize a rodent problem around your chickens.
1. Clean the Coop
Keeping the area around the chickens’ coop tidy will help deter rodents, especially rats, by leaving them without a place to set up house. Make sure grass around your coop is always cut neatly, and remove any scrap lumber or brush piles that are near the area. Throw away empty feed bags or store away for future use—don’t let them pile up outside the door.
2. Build Barriers
Repair doors and floors to help restrict access to the coop. Total exclusion might not be practical for larger operations, but backyard chicken keepers will find benefits to it. Mice can squeeze through an opening the size of a person’s little finger. If possible, line the corners of small, elevated coops and chicken tractors, especially where walls and floors meet, with sheet metal or 1/4-inch mesh hardware cloth. It’s best if this is done from the outside to prevent rodents from chewing an entry point through the wood.
3. Store Feed Properly
Chicken feed should always be stored in a covered metal container. Heavy, industrial drums that have been thoroughly cleaned are best at keeping out rodents. Drums come in 30- and 55-gallon sizes and can often be purchased from farm-supply dealers. A simple metal trashcan works as an alternative if you don’t have access to drums. Make sure the container’s cover fits tight; otherwise, rats and mice will scale walls to jump into the container.
Also remove the chickens’ waterer from the area at night when they roost. Rodents often show up in droves in late summer, especially if it’s been hot and dry, looking for moisture. Be sure to replace with fresh water in the morning.
4. Set Snap Traps
If you find yourself with a rodent infestation, the best remedy is to physically remove them. Traditional snap traps can be very effective for both mice and rats; however, you will want to keep them out of reach of your chickens. Most hardware stores sell trap/poison containment boxes. These boxes typically hold a couple traps, protecting them from anything that can’t enter the small entrance hole.
Rodents naturally concentrate their travels against walls, so these boxes or stations should be placed in their natural line of travel. The entrance hole should be parallel and closest to the wall. Bait can be used, but isn’t absolutely necessary in this situation. Traditional baits, such as peanut butter or chocolate, will work fine.
Larger boxes and traps can be placed around the perimeter of the coop to catch rats looking for a meal. Rats are extremely wary of anything new in their territory and might avoid the boxes until they get used to them. In this case, the boxes should be installed a couple weeks before putting the traps in them to help overcome their natural wariness.
5. Set Colony Traps
Colony traps are multi-catch traps, meaning they can hold more than one mouse at a time. The small metal boxes have an entrance hole on either end that contains a one-way door, meaning mice enter and can’t get out. The nice part about them is they’re on duty 24/7 without maintenance, except removing trapped mice. Again, no bait is needed if placed against the wall in the normal travel route. All mice caught in a colony trap will be alive if you check them frequently, so you will need a plan for dealing with them. Mice are not at all wary of these devices and will enter them readily.
Colony traps for rats are like small cages. Again, the rats will hesitate entering them at first. My experience is once one finally goes in, they all go, but it might take days or even weeks.
6. Apply Rodenticides
Poisons are often a last resort for the chicken keeper and should be used with caution around your livestock or poultry. Always place poisons in containment boxes; in most areas, this is the only legal way to use them. Make sure the boxes are locked in some manner. Many of them snap shut and require a tool to open, while others need to be locked with a screw or similar fastener. This will keep them from opening and exposing the contents to non-target animals.
I prefer poison blocks over pellets, as the blocks can be fastened to the inside of the box and are more difficult for rodents to remove. Pellets can easily be removed from the boxes, which is hazardous to your flock.
When using any rodenticide, it’s important not to continually use the same one over and over, as rodents will eventually build up an immunity to the chemicals. If a rodent snacks on a poison block and gets a bellyache and then recovers, it is now immune to that particular cocktail, so it’s important to change it up frequently. It is also important to keep the boxes maintained—don’t run out of poison—and keep them well fed.
Be aware of secondary poisoning to domestic animals, such as cats and dogs, and in wildlife that might consume poisoned rodents. Secondary poisoning is rare, but it can happen.
7. Call a Professional
If you find yourself overwhelmed or simply just don’t want to deal with the mess of rodents, search the Yellow Pages or the Internet to find a professional in your area. PestWorld.org is a website operated by the National Pest Management Association that allows you to search for pest professionals in and near your zip code.