| 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
Rat 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.
Rattus norvegicus
Common Names: Norway rat; Common rat; Brown rat; Wharf rat; Sewer
rat
Adult Weight: 300 grams
Length: (head + body): 200-250 mm
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.
Droppings: 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. Range:
50 metres.
Feeding habits: 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.
Life cycle: Span: 9-18 months.
Sexual maturity: 2-3 months.
Litter size: 8-10 offspring.
Maximum reproduction rate: 7 litters per year.
Rattus rattus
Common Names: Ship rat; Black rat; House rat; Roof rat.
Adult Weight: 200 grams
Length (head + body): 150-220mm
Length (tail): 180-250mm, usually longer than head and body.
Fur, colour: Smoother and softer than Rattus norvegicus. Usually
black or grey.
Ears, hearing: Thin, translucent, large and hairless. Excellent
sense of hearing.
Eyes, sight: Large and prominent. Poor sight, colour blind.
Snout, smell and taste: Pointed, Excellent sense of smell and taste.
Droppings: Scattered. Spindle or banana-shaped, about 12mm long.
Habits, habitat: Non-burrowing. Nests mainly in walls, attics, vines
and trees. Active agile climber, rarely found in sewers. Rather
more erratic and unpredictable in habit than Rattus norvegicus.
Less wary of new objects than Rattus norvegicus. Range: 30 metres.
Feeding habits: Omnivorous, mainly fruits, nuts, grains and vegetables.
Consumes 25-30 grams per day, drinks water or eats food with high
water content.
Life cycle: Span: 9-12 months.
Sexual maturity: 2-3 months.
Litter size: 6-10 offspring.
Maximum reproduction rate: 6 litters per year.
Pest information supplied by Sorex.
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