Fancy rat (Rattus norvegicus) — species profile (taxonomy, geographic range, habitat, physical description, behavior, wild diet, reproduction, lifespan)
Authoritative first-hand species account (Animal Diversity Web, University of Michigan). All bullet facts are verbatim from the cited source and C1-substring verified.
Geographic Range
- Norway rats ( Rattus norvegicus ) are originally native to northern China.
- Following a series of introductions, the species had found its way to Eastern Europe by the early eighteenth century.
- By the year 1800, they occurred in every European country.
- Records show the first sighting of R.
Habitat
- norvegicus was native to forests and brushy areas.
- Today, however, Norway rats find preferred habitat to be alongside the rapid expansion of the human population.
- Nearly every port city in the world has a substantial population of these rodents.
- They occupy a variety of habitats including garbage dumps, sewers, open fields and woodlands, basements, and nearly anywhere else that food and shelter might be found.
Physical Description
- Rattus norvegicus is a rather large member of the mouse family.
- On average, these rats reach nearly 400 mm nose-to-tail, and weigh 140 to 500 g.
- Males are usually larger than females.
- In natural populations, these rats are covered with coarse, brownish fur (sometimes splotched with black or white hairs) on their dorsal surface, which usually lightens to a gray or tan color nearing the underside.
Behavior
- Mostly nocturnal or active at dusk, Norway rats go about digging burrows, foraging for food, and preparing nests during these hours.
- Often, these rats take up residence in areas near water.
- They are excellent swimmers, and are often referred to as "water rats." Foraging behaviors can take the rats on long nightly excursions to areas known to be rich in food resources via learned routes.
- There is much learning capacity in Norway rats.
- They are able to remember their way around complex sewer and burrow networks.
Food Habits (Wild Diet)
- Norway rats are excellent foragers.
- Using their sense of smell and touch, they are able to survive quite easily given that there is a steady supply of any type of food.
- In metropolitan areas, they survive mainly on discarded human food, and anything else that can be eaten without negative consequences.
- Some Norway rats living near the sea have been observed catching fish with their paws.
- Also preyed upon by Norway rats are chicks, mice, birds, and small lizards.
Reproduction
- The mating system of R.
- norvegicus is best described as polygynandrous.
- Social animals, Norway rats tend to breed in large groups.
- Once a female enters her six-hour estrus period, she may mate as many as five-hundred times with competing males.
Ecosystem Roles
- Norway rats are excellent competitors and will readily drive out competing rat species, such as Rattus rattus .
- Because of their foraging habits, Norway rats act as seed dispersers.
- Their burrows also tend to aerate the soil.
- As prey, they help to sustain predator populations.
Predation
- Rattus norvegicus is preyed on by any number of carnivorous mammals, birds, and reptiles.
- Humans also kill very large numbers of Norway rats as pests.
Conservation Status
- These animals are not a conservation concern.
- In fact, humans spend a great deal of effort trying to eradicate them.
- Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.
Lifespan
- The maximum lifespan of R. norvegicus is 4 years (in captivity).