Common Rat Species

There are two main types of rats that cause concern in the UK. The Brown Rat (or common rat) and the Black Rat. They are a common pest in both private homes and businesses.

Black Rat

(Rattus rattus)

Black rats are rare in the UK. Their appearance is usually confined mainly to ports.

Appearance

  • The black rat is between 16–24cm in length, with a tail longer than the head and body.
  • It grows to between 150–200g in weight.
  • They have 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 a year.
  • The gestation period is about 3 weeks.
  • It only takes between 12–16 weeks from birth for them to reach sexual maturity.

Habits

  • They often climb as they are incredibly agile.
  • It is rare for them to burrow and they are rarely found outdoors in the UK.
  • Their preferred food is moist fruits. Black Rats will eat around 15g of food a day and drink 15ml.

Brown Rat

(Rattus norvegicus)

Brown rats usually prefer ground living and burrowing, but sometimes they can be known to climb.

Appearance

  • The brown rat is up to 40 cm in length, 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 when compared to the Black Rat (Rattus rattus).

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.

Habits

  • The brown rat is the only species to occur in sewers in the UK.
  • Preferred food is cereals, although they are omnivorous.
  • They will eat around 30g of food a day and drink 60ml.