Rats are a worldwide pest due to their capacity to cause structural damage, to spread life-threatening diseases, and to compete with man for food.
The species most commonly found in Europe is known as the Norway Rat (Rattus norvegicus). A less commonly found species, the Black or Roof Rat, (Rattus rattus), is largely restricted to port areas.
Rats live alongside man, invading his buildings and eating his food. Rats transmit disease, which are potentially fatal to man such as Weil's disease and murine typhus.
They also carry organisms which can damage man's health such as Salmonella bacteria, viruses and parasites such as nematodes and worms.
Damage by rats to the fabric of buildings can be costly. Fires can easily be started after a rat has gnawed a cable. Gas and water pipes are also at risk and rat burrowing can undermine foundations and damage water courses.
Physically very strong, rats have been known to survive for two days in open water, to swim a mile in open sea and to get through a gap of less than 25mm.
Common names: Norway rat; Common rat; Brown rat; Wharf rat; Sewer rat
Adult Weight: 300 grams
Length (head + body): 200-250mm
Length (tail): 150-200mm, shorter than head and body
Fur & colour: Harsh and shaggy. Brown and black on upper head and body, grey or off white underneath.
Ears & hearing: Thick, opaque, short with fine hairs. Excellent sense of hearing.
Eyes & sight: Small. Poor sight, colour blind. Snout, smell and taste: Blunt, Excellent sense of smell and taste.
In groups, but sometimes scattered. Ellipsoidal capsule shaped, about 20mm long.
Habits & habitat:
Does burrow. Lives outdoors, indoors and in sewers. Nests in burrows. Can climb, though not agile. Very good swimmer. Conservative, somewhat predictable in habit. Will avoid unfamiliar objects, e.g. bait trays, placed on runs, for some days. Need to gnaw to keep their constantly growing incisor teeth worn down. Creatures of habit; will leave regular runs to & from feeding areas.
Omnivorous, more likely to eat meat than Rattus rattus. Consumes up to 30 grams per day, drinks water or eats food with high water content. Will hoard food for future consumption. Most likely to eat at night. Range 50 metres when looking for food.
Life cycle: 9-18 months
Sexual maturity: 2-3 months
Litter size: 8-10 offspring
Maximum reproduction rate: 7 litters per year
Rodents can gnaw through materials such as steel, cement and plastic including electrical wiring.
Rodents have continuously growing incisor teeth that are used for gnawing.
To keep their incisors at a manageable length rodents have to constantly gnaw.
A female rat and her offspring can theoretically produce 2,000 rats per year.
Every year a rat produces 15,000 droppings, 6 litres of urine and sheds 300,000 hairs.
Rats and mice can spread salmonella through their droppings.
Leptospirosis or Weil’s disease is spread through infected rat urine to food and water sources.
For every 1kg of food eaten by rats and mice a further 3kg has been contaminated.
Rats require a separate source of drinking water, mice can survive on the moisture in food.
Over 20% of farm fires are caused by rodents gnawing through electrical cables.
To survive rats and mice have developed behavioural or physiological resistance to many current anticoagulants.
A rat can fit through a gap the width of an adult thumb (25mm to 30mm)
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