Black rat or Roof rat (Rattus rattus)

Appearance
16 – 24 cm long, with a tail longer than head and body together.
150 – 200g in weight.
Pointed nose, large ears and thin body in comparison to the common rat (Rattus norvegicus).

Life cycle
5 – 10 offspring per litter; 3 – 6 litters per year.
Gestation period about 3 weeks.
12 – 16 weeks from birth to sexual maturity.

Habits
Uncommon in Portugal. They appear mainly in harbours.
They often climb, are agile, hardly dig, and rarely live outdoors.
They prefer to feed on moist fruits.
They eat about 15g of food per day and drink 15ml of water.

Common Rats (Rattus norvegicus)

Appearance
Up to 40 cm long, with a tail shorter than the head and body put together.
Weighs 350 – 500 g.
Thick nose, small ears and fatter body compared to the black rat (Rattus rattus).
Life cycle
7 – 8 pups per litter; 3 – 6 litters per year.
Gestation period about 3 weeks.
10 -12 weeks from birth to sexual maturity.

Habits
They usually live on the ground and dig burrows, but also climb occasionally. It is the only species that can be found in sewers.
Cereals are their favourite food.
They eat about 30g of food per day and drink 60ml of water.

Domestic Mice (Mus domesticus)

Appearance
7 – 9.5cm long, with a tail of almost identical length.
12 – 30g in weight.
With fairly small legs and head and large eyes and ears, it is easy to distinguish from the young common rat (Rattus norvegicus).

Life cycle
4 – 16 offspring per litter; 7 – 8 litters per year.
Gestation period about 3 weeks.
8 – 12 weeks from birth to sexual maturity

Habits
They usually live on the ground and dig burrows, but they also climb often.
Cereals are their favourite food.
They eat about 3g of food per day and can survive without any additional water. They will drink up to 3ml per day if their diet is especially dry.