Mickey is the only mouse I like...
Mice and rats are a common problem on many farms. They eat and contaminate livestock feed, damage facilities, and are carriers of disease. This winter, mice have been a problem in a barn laboratory and a feed mixing/storage area at Miner Institute. The lab and mixing/storage area provides everything a mouse needs to survive…abundant food sources, shelter with plenty of hiding places, and a cat-free environment.
By Heather Dann, from Miner Institute Report
After finding some mouse droppings around the lab we causally tossed a few bait sticks and glue traps out around the lab. The initial harvest was good. However, the surviving mice quickly replaced the mice that were harvested. After a few more attempts of baiting and trapping with limited success, I learned that controlling mice takes a well-organized effort. The casual approach of putting out bait with little attention to cleaning or removing feed sources has little effect on reducing the mouse population long-term. The mouse population grew and caused damage to grain bags stored on pallets. In addition, the population is leaving a dirty mess behind on floors, counters, shelving units, and supplies.
After a bit of time spent reading about mice and visiting with a rodent control professional, I’ve learned there are three key elements to rodent management: prevention, monitoring, and control. Proper construction and maintenance of barns helps prevent rodents from entering. If rodents get in, then eliminating hiding places and nesting sites are important. Our mixing/storage area had many places for mice to hide, burrow, and nest with lots of miscellaneous equipment and pallets of grain stored in it. Mice can climb and jump so it’s recommended that equipment and feed be kept at least 12-18” off the floor and at least 9-18” from a wall. Our maintenance crew built a metal table ~2’ high to store pallets. The table seems to be working so far. Removing the source of feed is important for population control. However, this is a challenge on most farms and at the Institute. Keeping feed in “rodent-proof” bins and containers is recommended.Mice are capable of gnawing through many different materials, including plastic, rubber, vinyl, and wood. Mice can squeeze through an opening as small as ¼”. Steel wool and caulk can be used to fill in the small openings. Reducing and cleaning up feed spillage is critical also.
Monitoring is important to identify early signs of an increasing mouse population. Common signs include:
• Droppings along walls, behind objects, and near feed that are ~¼” in size (rice size).
• Sounds of gnawing and climbing in walls and ceiling.
• Gnawing marks that result in pieces of wood or other material on the floor or around bins and pallets.
• Smudge marks that are on walls, pipes, or rafters left from the dirt and oil on the fur.
• Musky odor.
• Visual observation of mice during the day indicates an established population since mice are most active just after dusk and shortly before dawn. One rule of thumb is that there are ~25 mice for every one that is seen.
Mice are very prolific, so monitoring and early intervention is key. A mouse can start reproducing at ~6-10 weeks of age and have 5-8 litters with each litter having ~5-6 pups. The pregnancy is short (21 days).
Currently we’re focusing on the control element of rodent management. It’s an integrated approach that focuses on minimizing feed sources, hiding places, and nesting sites, cleaning to remove scent trails, and using rodenticides (toxic bait) and traps. There are many types of bait available for use, and selecting the appropriate bait can be confusing. Based on discussions with a rodent control professional we’re using a combination of feed and liquid bait stations. Liquid bait stations can be very effective in barns where there are feed sources that can’t be eliminated. The liquid bait stations contain diphacinone. The feed bait stations contain bromadiolone and cholecalciferol which are effective in 1-3 feedings and kill warfarin-resistant rodents. Interestingly, cholecalciferol is vitamin D3 which is toxic to rodents at high levels. The use of a bait station protects children, pets, birds, and livestock from the poison, keeps the bait dry, and provides a small entrance that attracts mice to feed. In addition to the bait stations, we’re using glue traps and curiosity traps (e.g. Tin Cat trap) that don’t require bait. The glue traps are a challenge to use in cold and dusty environments and haven’t been very effective for us this winter. The Tin Cat traps are working well for us. The burrow-shaped opening welcomes the mice into the trap. The traps need to be checked at least weekly. It’s recommended to set traps close to walls, behind objects, in dark places, and in high mouse activity areas.
By Heather Dann, from Miner Institute Report