Rat species

There are two main types of rats that cause concern in New Zealand. The Brown Rat (or common rat) and the Black Rat, which was introduced to this country are a common pest in both private homes and businesses.

• Black rat
• Brown Rat

Black Rat

(Rattus rattus)

Black rats can be found in coastal towns and in many urban environments across New Zealand

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.

Life cycle and habits of the Black Rat

Lifecycle

• 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 are incredibly agile and very good climbers.
• 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 and habits of the Brown Rat

Lifecycle

• 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

• Preferred food is cereals, although they are omnivorous.
• They will eat around 30g of food a day and drink 60ml.