Two species of rat are found in the
UK, the Black (or Ship) Rat and the Brown (or Common)
Rat. The Black Rat is scarce and found
in only a few isolated locations in the UK. The Brown
Rat is the species that is usually
The Brown, or Common
Rat (Rattus norvegicus)
The Brown Rat’s colouring can vary but
is usually brown to grey with a lighter coloured
underside. It is larger than, and has
a more well built appearance than a mouse and it has
small ears and eyes. The tail is
slightly shorter than the head and body length and is quite
thick. Overall length including the
tail is up to 270mm. The Brown Rat usually lives for an
average of 18 months. The female rat
can produce several litters of 6 – 10 young a year, with
the youngsters being able to breed at
3 months old themselves.
The Brown Rat is by far the most
abundant of the two rat species and is widely distributed in
both urban and rural areas. It occurs
both indoors and outdoors and as it is a good swimmer
is often associated with watercourses
and sewerage systems.
The Brown Rat is an active burrower
and sometimes a complicated tunnel system with
several openings is produced.
Typically, such a system can be found around the outside of
buildings, in embankments, hedgerows,
refuse tips and other similar situations. The burrow is
used to rear young and as a place to
rest away from predators. They can also exploit cavities
in walls, roof spaces and building
ducting. They may also find their way into buildings through
defects in nearby sewerage systems in
which they may be living, or through small openings in
buildings. If possible Brown Rats
prefer to live close to sources of both food and water and
can be significant problem in food
storage sites. They are omnivorous and will adapt to just
about any food source. They have to
gnaw on objects to keep their incisor teeth from growing
excessively, and this can lead to
damage to pipe work and electrical wiring.
Brown Rats can also climb walls if the
surface is rough enough and they can also climb
drainage pipes. They are also able to
jump to height of 0.7m. They’re also quite nervous of
new objects, taking some time to
explore new things. They can carry a disease known as
Weil’s disease which is passed to
humans by the rats urine and they can carry other diseases
and parasites. Surprisingly though
they spend a large amount of time cleaning and grooming
What to look for?
· Rat droppings are usually the most common
evidence. Usually about 12mm in size,
dark in colour and found in areas the
rats have visited.
· Burrows may also be evident, with entrance
holes usually around 70 – 120mm in
diameter. ‘Runs’ may also be evident –
as the rats will use familiar routes, distinct
pathways may be seen. Footprints can
also be seen in dust or mud.
· Rats will brush their fur against objects
they have been running close to, and dark,
greasy ‘smears’ can sometimes be seen.
· Damage to packets of food, electrical cables,
gas and water pipes, woodwork.
Shredded paper used for nesting can be found.