How to know if your farm has a problem?

Producers should not be embarrassed to admit they have a rodent problem. Surveys in Ontario indicate that 80% of poultry producers and 89% of swine producers have rodent problems. Chances are, rats and mice are a problem on your farm. The embarrassment and costs occur if something is not done to confront the problem.

Monitoring your barns is an important step in preventing and/or controlling rodent populations. Traditional rodent control methods such as baiting and trapping can also be used as a monitoring tool. Thorough record-keeping of bait disappearance can warn farmers if their rodent population is increasing. This is especially important in the fall, when rodents start to look for suitable wintering sites. Be aware that bait can become stale and mouldy, and must be refreshed often to prevent bait aversion and maintain the effectiveness of your monitoring program.

The following are signs of rodent infestation:

• Sounds: Gnawing, climbing noises in walls, squeaks.
• Droppings: Found along walls, behind objects and near food supplies.
• Burrows: Rat burrows are indicated by fresh diggings along foundations, through floorboards into wall spaces.
• Runs: Look for dust-free areas along walls and behind storage material.
• Gnawing marks: Look for wood chips around boards, bins and crates. Fresh gnawing marks will be pale in colour.
• Rodent odours: Persistent musky odours are a positive sign of infestation.
• Visual sighting: Daylight sighting of mice is common. Rats are seen in daylight only if populations are high. Quietly enter your barn at night, wait in silence for 5 minutes and listen for the sound of rodent activity. Look around with a powerful flashlight; rat eyes will reflect the light.
• Smudge marks: These may be found on pipes or rafters where dirt and oil from their fur leave a greasy film.

It is a generally accepted rule of thumb that there are approximately 25 mice or rats for every one that is seen. If you see rats and mice during daylight hours, it may indicate a severe infestation, as the population and feeding pressures are so high that juveniles are forced to forage during the day.