Identifying Rodent Infestations on Farms

Before embarking on a rodent control program it is important to understand the precise nature of what infestations exist on farm in order to effect the optimal baiting program.

 

 

The key signs of farm infestation

A thorough inspection of the farm should be made regularly to look for the tell-tale signs of rodent infestation. This is especially important because the rate at which rodents breed means that serious infestations are rapidly established. It is important to note that rats and mice are almost exclusively nocturnal feeders and adept at seeking cover so that only a minority of the population are ever seen. This makes it easy for farmers to under-estimate the extent of infestation. In the absence of physical sightings it is important to look for:

Holes and nests
Common rat holes are about 8cm in diameter. Outdoors they will be found in refuse heaps, under sheds, in banks, hedgerows, around haystacks and similar places. Indoors, holes may be gnawed in floors, partitions, cavities and at the base of doors. Mouse holes are easily distinguishable from rat holes by their smaller size (about 2cm diameter). Rats living outdoors make nests with dried grass and leaves in burrows. Indoors both rats and mice make nests using all kinds of materials such as shredded paper, card and insulation materials.

Runs
When travelling to and from burrows or nests, rats and mice tend to use certain routes regularly. In doing so rats make very distinct narrow pathways or “runs” that are often visible in the vegetation around farm buildings. Runs made by mice are generally not so obvious except in dusty areas.

Smears
Rats in particular like to move with their bodies in contact with a solid object and greasy stains or smears can often be seen along building walls. When moving along the tops of walls in buildings, rats and mice may have to scramble under joists or other obstructions and where they do this, characteristic black loop-shaped smears will develop on the wall surface. Mouse loop smears are similar to those of rats, but smaller.

Droppings
The number of droppings, their position and age will indicate whether rodents are abundant and where they are moving and feeding . Fresh droppings remain shiney, soft and moist for a few hours, becoming progressively more dull, hard and dry with age. Rat droppings are spindle shaped and about 15-20mm long, they are often found in groups on runs, mice droppings are rod shaped, about 3-6mm long, and are generally scattered.

Foot prints and tail marks
These may often be seen where rats and mice have been running over dusty or muddy surfaces. Clear footprints will show the four toes of the fore feet and the five toes of the hind feet.

Signs of damage
The more rodents present on farm, the more extensive and visible the damage. This damage includes gnawed materials such as wood, plastics, cables, pipes, silage bags and sacks. Damage by rats can usually be distinguished from that done by mice, often by the size of the teeth marks in partly eaten food. With grain, rats tend to leave half grains, whereas mice tend to nibble around the grain leaving a bitten core. In the case of whole grain, mice may also reject the outer husk altogether.