Rats - Advice for identifying and controlling

What do they look like?

There are two species of rats in Britain, Rattus norvegicus, commonly known as the Brown Rat, and Rattus rattus, commonly known as the Black Rat or Ship Rat.

The Brown Rat is the larger, often weighing over half a kilo and measuring about 23cm, without counting the tail.  It has a blunt muzzle, small hair covered ears and a tail that is shorter than its body length. 

The Black Rat weighs only half as much and is slightly shorter.  It has a pointed muzzle, large, almost hairless ears, a slender body and a long thin tail that is longer than its body.

How do you spot them?

Rats are intelligent, social animals - they can jump, swim and climb very well and they prefer to move around in darkness although they can often be spotted during the day.

Possible indications include:

• Runs - Rats establish runways, which are regularly used in travelling between food and cover.  These are often visible in the vegetation around buildings or fences
• Smears - Rats like to move with their bodies in contact with a solid object and greasy coat stains are often seen along walls or the sides of well travelled objects
• Droppings - The rat's droppings are spindle shaped, about 18mm long, dark brown or black, and normally seen in groups
• Gnawing marks - Signs are often seen at entrances to stores, packing cases or buildings
• Tracks - Foot and tail prints may be seen, although these may be difficult to properly identify
• Damage to property - furniture and bedding may be damaged by rats
• Scratching noises may be heard in cavity walls or under floorboards

How do they affect humans?

Rats are a serious hazard to public health.  Rats can contaminate food with droppings and urine and they are also capable of spreading many diseases from their surroundings in sewers and refuse tips and can transmit food poisoning, Weil's disease, murine typhus, rat bite fever, trichinosis and other diseases.

The Life Cycle

Both species of rats breed rapidly and become sexually mature in about three months.  Each female may produce from three to twelve litters of between six and eight young in a year.  Brown rats will burrow underground or into soft material to make a nest.  Refuse tips, loose soil under sheds and earth banks are all likely sites and chewed paper, straw or insulation material may be incorporated as nest material.  The young are born blind, helpless and naked and depend on their mother for food for about three weeks before they are sufficiently developed to take solid food.

Rats, like mice, need to gnaw to keep their constantly growing incisor teeth worn down.  They damage woodwork, plastic and lead pipes and will sometimes strip insulation from electrical cables by their gnawing.

Rats will hoard food for future consumption.  They feed mostly at night and an average rat will eat 50g of food a day.

How do you control them?

• Regular removal of domestic waste - keep rubbish in sealed bins with well fitting tops
• Do not scatter food for birds in the garden - use a feed container or only leave food on the ground for a short time and not overnight
• Fit wire ball cages to the tops of downpipes and soil stacks which will prevent rats crawling up inside the pipes
• Manhole and inspection chamber covers should be well fitted and in good repair.  Any holes appearing around the edges of the cover should be investigated.
• Compost bins should stand on a concrete base to prevent tunnelling in from the bottom
• Repair any holes in internal/external walls
• Remove empty and disused hutches/cages
• Garages, outbuildings, sheds and rabbit hutches should be kept clutter free.  Store animal feed in rat-proof containers.  Outbuildings should be regularly inspected for any signs of rodent activity

Treatment

North Shropshire District Council provides treatment for rats free of charge in domestic properties.