Preparing your barn for winter - Pest management series part two

This 4-part series will address different areas of pest management and assist farmers with building and maintaining a pest management plan that is feasible for their options.

Brown mouse eating shelled peanuts.
Mice have large ears with triangular-shaped heads.

Understanding Rodent Types

Many times people assume that all rodents can be treated the same and controlled with the same practices. However, specifically the behavior of mice and rats are very different and managed differently, depending what type of pest issue you have.

Rats are generally larger in size than field/farm mice and can cause more damage. Physically, rats have smaller ears in proportion to their bodies and are known to live up to two to three years. The heads have a blunter snout and they have long hairless tails. Rats are known to have very poor eyesight, including being completely color-blind, they are typically shy and nervous animals and this results in them taking a familiar or similar route when they travel. Generally known as creatures of habit, rats stay close to walls and structural parts of the buildings and will follow the same path to and from a feed or water source. Rats easily exploit the structure weaknesses of a building, especially in the fall and winter months. Rats also require a water source to remain viable. Obvious signs of rat infestations are defects in the building structure, broken pipes, defective covers and channels in brickwork. Rats take time to approach new objects or materials and when baiting rats, it may be beneficial to use existing materials instead of introducing something new like a bait station. This will help decrease the time it takes a rat to approach and take the bait. It is also a good practice to find the path that rats generally take, identified by droppings and to place the bait next to their typical path. Rats also tend to carry bait away and hoard it.

On the other hand, mice are smaller in size and also have poor vision, however they can distinguish all colors except for the color red. Their ears are larger and they have been recorded to live over five years in the wild. Mice have triangular-shaped heads with long, thin and hairy tails. Compared to rats, mice are more inquisitive, more likely to approach new items and do not need to travel the same path. They are known to travel in zigzag patterns, not necessarily keeping next to walls. Mice exist in the fabric of a building, feeding and living in the same area. They are easily introduced through materials, feed and supplies that are brought into the farm. Different from rats, mice are less responsive to seasonal changes, do not need a water source, and the population typically exists year-round. When baiting mice, the proper technique is to place small amounts of bait over a large area or location, making it easier for the mice to find and eat the bait.

Signs of Rodents

There are several signs that rodents are present in your barns. Sounds, such as squeaking, are the most distinctive. Rats and mice are known to gnaw wood and wires and climb along walls. Rodent droppings will be seen around walls, behind objects and near the food supply. Rats and mice will also cause a dust-free spot to where they have been traveling, preferably around the outer walls and floorboards. Along the outside of the building, burrow patterns will be seen as they are trying to get into the barn for warmth and food. Smudge marks on the pipes and rafters where the dirt and oil rubbed off by their fur, which will typically leave a greasy film, also indicates rodents are inside the barn. Most likely, rodents will be active during the day, but come into the barn during the night due to the quiet nature of the barn during that time of day. It is important to note that rats typically follow the same path when traveling and evidence such as defecation will be seen in the same area.

Rodent Proofing the Barn

Taking the time to rodent proof your facility is an essential component to your pest management plan. This also helps maintain the integrity of your biosecurity practices and health of the barn. Having proper construction is the first line of defense. The initial construction footings should extend down around 19 inches into the ground to deter burrowing. Routine inspections and maintenance on the facility should be done to help deter rodent infestations. Usually, rodents are known to enter the barn from cracks around the door frames, under doors, broken windows or ripped curtains, water lines and utility hook-ups, vents and holes surrounding the feed augers and bins. These areas, in particular, should be constantly looked at to decrease the risk of rodents in the barn. Installing baffles around cables and pipes and placing kick plates on the lower edge of the doors discourage rodents and help prevent gnawing. Flaps or crushed wire mesh on inlets will also help prevent rodents from entering the facility.

Going hand-in-hand with rodent proofing is maintaining the hygiene of your barn. Barns that are above average in cleanliness are less likely to attract rodents. Best practices include cleaning up feed spills quickly and disposing of spoiled or rotten feed properly, where rodents cannot access it. Removing trash and debris from the facility will also help maintain hygiene and limit exposure to rodents.

Additional articles in series

Part one – Introduction to pest management

Part three – Rodent control methods

Part four –  Pest control records and monitoring


Buckle, Alan, et al. “Anticoagulant Resistance in the Norway Rat and Guidelines for the Management of Resistant Rat Infestations in the UK.” Rodenticide Resistant Action Group, June 2010,

“Rodent Control on Farms.” The Pig Site, 19 Feb. 2015,

Timm, Robert M. “Controlling Rats and Mice in Swine Facilities.” Extension, 20 Apr. 2010,

Did you find this article useful?