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This rat species usually has a grey brown colour on their back. Their abdomen are lighter, however there is a large variety in colours, up to white (albino). It is an animal with a firm build, with a fairly blunt snout, a very hairy body and clearly visible ears. The almost bald, tick tail (about 20 cm) is shorter than the body (about 25 to 30 cm). The weight of an adult brown rat is about 400-500 grams.

Brown rats are very common; they are so-called ‘culture followers’ because they are very able to adapt to humans. They are great swimmers and diggers and feel at home in sewers, at landfills in and around corn fields etc. They feed themselves with many products (grains, vegetables, fruit, fish etc.) and can therefore be found everywhere that has a big (and messy) food supply, preferably in the vicinity of water.

The brown rat has a rapid development; the females reach sexual maturity after about 3 months and can have up to 15 birth cycles with 5 – 10 young each. The average lifespan in the field is about a year.

As described above, this rat species prefers to be in the immediate vicinity of people and their buildings, supplies and waste. In areas with a lot of water, they can spread Weil’s disease; and in areas of intensive livestock farming they can spread various diseases as well. They contaminate and damage supplies and because of their urge to gnaw (for instance cables) they can cause short circuit, leakage and machine failure. For that reason, brown rats are undesirable in the direct vicinity of people.

Proper architectural provisions, such as properly closing doors, narrow ventilation openings, one can keep rats outside. Good hygiene (storage and removal of waste, tidy storage of products, regular cleaning of areas etc) is important to prevent the presence of rats.

After a thorough inspection of and around the object, bait depots are installed at strategically chosen places. In these bait boxes or crates, toxic bait is placed. The rodenticides used, approved by the Dutch College Toelating Bestrijdingsmiddelen are so called anticoagulantia (anti-clotting agents). These baits should be offered at least several weeks to cause death. After 2 to 7 days of absorption, death occurs after 7 to 14 days.