Up to 40 cm in length, with a tail shorter than the head and body.
350 - 500 g in weight.
Blunt nose, small ears and a thicker body when compared to the Black Rat (Rattus rattus).
7 - 8 young per litter; 3 - 6 litters a year.
Gestation period of about 3 weeks.
10 - 12 weeks from birth to sexual maturity.
Usually ground living and burrowing, but sometimes climbs. The only species to occur in sewers in Ireland.
Preferred food is cereals.
Will eat around 30 g of food a day and drink 60 ml.