Brown rat
Rattus norvegicus
Gabriele Vaudano · 13867 Flecchia BI
Key facts in one look
- Size
- Body 17–25 cm, 140–500 g
- Diet
- Omnivore
- Status in Georgia
- Lives with people, widespread
- Habitat
- Settlements, waterside, up to 2,400 m
- Family
- Muridae
- Conservation
- LC / LC
The brown rat (Rattus norvegicus) is the larger of the two rats living in Georgia: up to 25 cm in body length and up to 500 g. Its homeland is East Asia, and people, above all ships, spread it around the world. In Georgia it has been found from the sea coast to mountain villages, from Batumi and Poti to Tbilisi, Borjomi and Mestia. It keeps to riverbanks, basements, sewers and rubbish dumps. It carries the agents of leptospirosis and other diseases, so never touch a live or dead rat with bare hands.
Identification
Brown rat: how to identify it
A heavy, short-eared rat with a broad, slightly elongated muzzle. The tail is always shorter than the body. It is most easily confused with the black rat, which is smaller and has a tail longer than its body.
The body without the tail is 17–25 cm long and weighs 140–500 g. Larger animals, up to about 40 cm, turn up rarely. The tail reaches 19.5 cm and is always shorter than the body.
The fur is greyish brown rather than grey, with long, glossy guard hairs. The belly is whitish, with a clear line where it meets the flanks. Young rats are almost grey and turn more reddish with age. Fully black animals turn up rarely.
The black rat has a narrower muzzle, large rounded ears and a tail longer than its body. The brown rat has small ears, a broad muzzle and a short tail. Black fur does not reliably separate them, so look at the tail and the ears.
Colour
Swatches are illustrative. Do not identify a species by colour alone.
Often confused with
A rodent tied to water: in the wild it lives on the banks of rivers and other water bodies. Alongside people it chooses basements, lower floors, warehouses, sewers, rubbish dumps, vegetable gardens and parks, as long as water is close. In the wild it digs a simple burrow 2–5 m long and up to 50–80 cm deep. In the Greater Caucasus it climbs to 2,400 m in houses and to 1,400 m in vegetable gardens. In Georgia it has been found on the Black Sea coast, from Gagra and Sokhumi to Poti, Chakvi and Batumi, near Zestaponi, in Tbilisi and Gori, in Borjomi and Khashuri, in Aspindza, Mestia, Tsageri and Pshavi.
The brown rat map combines public iNaturalist observations. Regions are taken from the records-by-region table, and the status column separates regions with enough records from regions with too few records. Record counts reflect observation effort rather than population density. One region has enough records: Tbilisi.
Data: Reptiles.ge + iNaturalist · Methodology
- Field observation
- Several records in one spot
- Photo record
- Region with records
It is omnivorous and needs more animal food than most rodents. In the wild it eats fish, amphibians and molluscs, and from plants, seeds, grain and juicy parts. Alongside people it eats whatever it finds: food, waste, livestock and poultry feed. It eats 20–25 g of food a day, 7–10 kg a year. It needs 30–35 ml of water a day and dies within a few days without food or water.
It is active mainly at dusk and at night, but near people it easily shifts its daily rhythm. It lives in groups with a complex hierarchy among males. A group marks a territory of up to 2,000 m² with scent and defends it against strangers. It swims and dives well, runs at up to 10 km/h and jumps up to 1 m from a standstill. In the wild it breeds mainly in the warm season, in heated buildings all year round. In the wild a female has 2–3 litters a year, in buildings up to 8. A litter holds 1 to 20 young, 8–10 on average. Gestation lasts 22–24 days; the young are born naked and blind, open their eyes at 14–17 days and become independent at 3–4 weeks. In the wild it lives up to 3 years, but most never reach 1.5 years.
Globally the brown rat is Least Concern (LC, 2016). In Georgia the 2021 national assessment also lists it as Least Concern (LC), with a stable population. It needs no protection: people have destroyed rats for centuries without any effect on their numbers or range. In the temperate zone of Europe it is pushing out the black rat. It is food for many predatory mammals and birds.
Related guides
Continue with related pages
Almost everywhere people live. It has been found on the Black Sea coast from Gagra to Batumi, near Zestaponi, in Tbilisi, Gori, Borjomi, Aspindza, Mestia and Pshavi. It keeps close to water and chooses basements, sewers and rubbish dumps. In the Greater Caucasus it climbs to 2,400 m in houses.
It does not attack, but it spreads disease. It carries more than 20 dangerous infections, leptospirosis among them. You can catch a disease through a bite, a scratch, urine, droppings or fleas. So do not touch a rat with your hands, and see a doctor after a bite.
By the tail and the ears. The brown rat's tail is always shorter than its body, its ears are small and its muzzle broad. The black rat has a tail longer than its body, large rounded ears and a narrow muzzle. Do not trust the colour: brown rats are sometimes black, and black rats are often brown.
Very fast. A litter holds 8–10 young on average, and gestation lasts just over three weeks. In the wild a female has 2–3 litters a year, in heated buildings up to 8. So if you notice signs of rats in your house, do not put the problem off.
References
What this profile is based on
Species profiles are compiled from peer-reviewed literature and established biodiversity databases, and are reviewed as new taxonomic and conservation data become available.
Prepared by the Reptiles.ge editorial team from the sources listed here.
