Norway Rat

Norway Rat, also called the Brown Rat- NPS (public domain)

Black Rat

Image labeled as being a Black Rat photographed at the London Zoo- Wikimedia Commons by user Liftarn (GNU license)

The Norway Rat and Black Rat are present in Connecticut.

The Norway Rat, or Brown Rat, has brownish fur and a long naked, light-colored tail 5-9 inches long. Norway Rats usually weigh 7 to 17 oz.

The Black Rat, or Ship's Rat, has brown to gray to fur, sometimes black, and a long dark tail 6 1/2 to 10 inches long. Black rats usually weigh 4 to 12 1/2 oz.

These two rats are Old World species. They were brought to the US during the colonial period from Europe and are now well-established. Norway Rats are all over the continental US and along the southern edge of Canada. Black Rats range mostly along all the edges (except the US/Canada border) and coastal regions and states of the US. They have moved farther into inland states in the west. Both are active year-round and mostly nocturnal. They live where humans do. Norway Rats inhabit farms, cities, sewers, and houses everywhere. Black Rats are more commonly associated with seaports and buildings near the water than Norway Rats. Black Rats do better in warmer climates.

Rats are thorough omnivores. They eat whatever is edible. Grain, garbage, soap, candles, plants, insects, meat, fruit and eggs are all on the menu.

Rats breed year round with multiple litters, up to 12 for the Norway rat, a year.

These rats are not popular with humanity. They will invade and consume large amount of foods on farms. They can kill chickens. They are known to carry diseases and are closely associated with the bubonic plague and typhus. Their droppings contaminate the uneaten portions of goods where they have fed.

Norway rats make extensive tunnel systems. They are good climbers and swimmers and live in loose colonies. They are as successful in an urban setting as on farmland. They self-regulate their population by producing fewer young when population pressure is high.

Black rats used to be all over the US but have been replaced by the Norway Rat in many areas of the country. Black Rats are more common onboard ships than Norway Rats, hence their other common name, Ship's Rat. They are therefore transported easily among ports. They are a particular pest in seaport warehouses and in goods on docks. They are very good climbers and sometimes nest in trees or vines.

The white rats used in research are often albino Norway Rats. People have specially bred varieties of rats that are kept as pets, and many of these are Norway Rat varieties. Reputably-bred domestic rats can be different colors and patterns and are free of diseases. They are no worse than pet hamsters or gerbils.

Both Norway and Black Rats are eaten by owls, hawks, snakes, weasels, dogs and cats.

Neat Facts

Norway Rats did not originate in Norway and Black Rats are rarely Black.

Norway Rats are believed to have originated in Central Asia and probably spread through Europe during the 1500s to the 1700s. They came to the US in grain shipped by Hessian troops who were fighting for the English in 1776.

Black Rats probably orginated in Southeast Asia and spread through Europe a long time before the Norway Rat arrived. Black Rats are believed to have reached the Americas in the 1500s onboard Spanish ships, and to have come to the US in early 1600 with Jamestown colonists.