The brown rat, common rat, sewer rat, Hanover rat, Norway rat, Brown Norway rat, Norwegian rat, or wharf rat (Rattus norvegicus) is one of the best known and most common rats. The fur is coarse and usually brown or dark grey, while the underparts are lighter grey or brown. Brown rats have acute hearing, are sensitive to ultrasound, and possess a very highly developed olfactory sense.
Ten Facts about Norway Rat
- The length can be up to 25 cm (10 in), with the tail a further 25 cm (10 in), the same length as the body.
- Adult body weight averages 550 g (19 oz) in males and about 350 g (12 oz) in females, but a very large individual can reach 900 g (32 oz).
- Their average heart rate is 300 to 400 beats per minute, with a respiratory rate of around 100 per minute.
- Brown rats are capable of producing ultrasonic vocalizations.
- The brown rat is a true omnivore and will consume almost anything, but cereals form a substantial part of its diet.
- The brown rat can breed throughout the year if conditions are suitable, a female producing up to five litters a year.
- The gestation period is only 21 days and litters can number up to fourteen, although seven is common.
- The maximum life span is up to three years, although most barely manage one.
- They are spreading in Asia, Northern China and Mongolia, the brown rat spread to other parts of the world.
- Cats, Dogs, Snakes are some of their predators.
