Common Rat Species

The black rat is rare in the UK. They are usually confined to port areas. It is rare to find the Black Rat outdoors in the UK. It is also rare for them to burrow. The black rat is extremely agile and will often climb.


The black rat is between 15-25 cm in length with a tail longer than the head and the body. It grows up to between 150-200g in weight.It has a pointed nose, large ears and a slender body when compared to the Brown Rat (Rattus Norvegicus)

Life Cycle

Black rats produce 5-10 young per litter and have between 3-6 litters per year. The gestation period is about 3 weeks. It only takes between 12-16 weeks from birth for them to reach sexual maturity.


Black rats are expert climbers. Their preferred food is moist fruits however they are omnivorous and will eat almost anything. They will eat around 15g of food a day and will drink 15ml of water.

The Norway Brown Rat usually prefers ground living and burrowing, they are not particularly good climbers. They normally nest outdoors but can be found nesting in cellars and the lower parts of buildings.


The brown rat is up to 40 cm in length including the tail, with a tail shorter than the head and body. It grows up to between 350-500g in weight. It has a blunt nose, small ears and a thicker body.

Life Cycle

Rats have 7-8 young per litter, and between 3-6 litters a year. The gestation period is about 3 weeks. It only takes 10-12 weeks from birth to reach sexual maturity.


The brown rat is the only species to occur in sewers in the UK and quite often, where there are rats, there is a problem with the drains. Preferred food is cereals, meat and fish, they are omnivorous and they will eat practically anything. They will eat around 30g of food a day (approximately 10% of body weight) and drink 30ml a day and they need daily and easy access to both food and water.

Rats are well known to spread disease, damage property and contaminate food and animal feed. If rats are able to get into your home or business, they can introduce disease carrying parasites like fleas, lice and ticks and spread disease through their faeces and urine. As they are most active between dusk and dawn, it is often easier to spots signs of a problem, rather than an actual rat.

Rats pose a significant health risk to people and pets, via their droppings and urine, which are between 30 - 180 droppings and 16cc of urine daily.

Common diseases carried by rats:

  • Salmonella, food poisoning
  • E.coli
  • Cryptosporidiosis
  • Tuberculosis
  • Murine typhus also known as endemic typhus. This is caused by a bacteria carried by rats and their fleas.
  • Weil's disease, sometimes called Weil Syndrome is a severe form of Leptospiral Jaundice, which can lead to liver damage. The pathogen is transmitted in urine and most often infects a person by exposure to contaminated water.
  • Hantavirus this pathogen is known to cause acute hemorrhagic fever and is transmitted via urine, saliva and rodent excrement.
  • Listeriosis rats are known as a reservoir for this bacterial infection, which can cause food poisoning and stomach bugs or in some cases more serious conditions such as septicaemia.
  • Rat-bite fever alternatively known as spirillary fever, it is passed from rodents to humans via urine or mucous secretions (from mouth, nose or eyes). It can also be transmitted via food or water contaminated by faeces or urine.

Rat Droppings

Rats tend to concentrate droppings in specific locations, unlike mice faeces which are scattered;. They also produce approximately 40 droppings per night. Brown rat droppings are a tapered, spindle shape, whilst black rats faeces are slightly more banana shaped. Both are dark brown and approximately 10 - 20 mm in length. If the droppings are soft and slightly shiny this suggests a current and active infestation as does a strong smell of urine.


Normally rats nest outdoors, but will nest indoors in cellars and lower portions of the buildings although they will stray into attics and roofs spaces if it's possible. An entry point of no more than 12mm is required for rats to enter the premises. They will eat practically anything, but they prefer meat, fish and cereals. However, they are suspicious of new foods (this is known as neophobia) and they also have extremely sensitive learned food aversions, meaning that they may initially only try a small piece of a new food to see whether or not it makes them feel ill and if it does, they will scrupulously avoid it in the future.

Damage to property

Rats constantly chew to help control the growth of their incisor teeth, which are specialized for gnawing. The upper incisors hold the object and the lower ones cut against it. The enamel on their teeth is harder than platinum, it's clear to see that gnawing rats can cause a great deal of damage in a property. They can chew through plastic, lead pipes, wood, mortar, uncured concrete, aluminum and other thin metals to get to food or water. The gnaw marks they leave behind are quite distinctive; two parallel, slightly recessed grooves that are approximately 4mm apart. They have been known to chew through electrical cables causing short-circuits, which are a fire hazard.

Scratching noises

Brown rats are not particularly good climbers and are more likely to be identified by a grinding or chattering noise they make with their teeth known as bruxing - as they scurry under decking, sheds and floorboards.

Rub marks

Rats use established times and routes along skirting boards and walls due to their poor eyesight. Grease and dirt on their bodies leave smudges and dark marks on both objects and surfaces they repeatedly brush against. These marks may indicate rodent activity, but as smears may remain for a long period of time, they are not a good gauge of an active infestation.


Rats leave tell tale foot and tail marks in dusty, less-used areas of buildings. With the use of a flashlight at a low angle the tracks are clearly visible. To establish if an infestation is active, sprinkle flour or talc onto a stretch of floor near the footprints and check for fresh tracks the daily.


Rats, especially brown rats, are well known for digging extensive burrow systems for shelter, food storage and nesting. They build burrows next to solid objects or structures (decking, garden sheds, garages etc.) and are also found in secluded, well vegetated areas such as gardens and wasteland.

Discovering rats in your home or business can be very distressing. On top of the health risks, rats have also been known to cause fires by chewing through wiring and cables. They can even gnaw through wood, plastics and mild steel. Professional rat control is the most effective and quickest way to get rid of rats. Expert treatments can prevent damage to your property and protect against diseases spread by this rodent.

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