Black Rat Fact File
The black rat has a round body coated with fur which is typically black but can be brown. The fur on the underside is white or grey and around the feet it is white or pink. They have a pointed head though in juveniles this is more rounded.
At the end of their body is a long tail measuring 18-26cm (7-10in) long with no hair on it. This assists them with balancing when climbing. They have large ears.
Their body will measure up to 24cm (9.5in) long and their weight varies between 150 and 250g (5-9oz). Males are typically slightly larger than females.
Black rats are omnivores which feed on almost any food which has helped their expansion across the globe. Foods which are generally consumed include fruits, grains, cereals and insect. Deceased animals (carrion) and feces of other animals are eaten.
They are considered a pest in many areas as they will enter agricultural areas and eat crops. They cause further damage to the crops by depositing their feces through them.
Captive 4 years
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The black rat originated in Asia where it was originally found in India and Pakistan. Through human activities they have been able to travel to every continent except for the polar regions.
They travelled to Europe in ancient times. It is believed they travelled to Australia with the first fleet.
It is believed that the species may have now been eradicated in the United Kingdom where it was once common.
Black rats are among the most widely distributed animals on Earth.
Black rats are highly adaptable and can be found in many habitats. These include forests, shrublands, grasslands and wetlands. They are often found in human inhabited areas including cities and farmland.
In some areas they have been driven out by the brown (Norway) rat and they have also been removed in some regions by pest control programs.
They may be found near water but unlike some of their close relatives do not swim and are not commonly found in sewers like some of those relatives.
Breeding occurs from March to November in most populations though in some areas they can breed year round. During this breeding period a female is able to produce as many as five litters.
Males may mate with multiple females in the same breeding period. In a given area one male will be dominant and have the greatest breeding success. Males are not involved with raising the pups and leave soon after mating.
The young are born after a 20-24 day gestation period.
Each litter includes between five and eight pups. This number is variable based on the weight of the mother. At birth the young are blind with the eyes not opening till 15 days old. Development is rapid and by 20 days old the young have been weaned.
Young are raised in a den which may be located in a tree. This is formed from sticks and leaves. While most nests are in trees they may also be dug underground.
Sexual maturity may be reached as early as five weeks old.
The black rat has sharp front teeth which grow throughout their life and allow them to chew through a wide range of items such as wood, plastic, electrical cables and more.
These animals are considered nocturnal but in many areas will be seen during the day.
Black rats are primarily arboreal and can climb extremely well.
They will form a group known as a pack which may include up to 60 members. These groups are able to intimidate much larger species such as dogs.
Each pack typically includes a single dominant male and two or three dominant females which will produce young.
A range of vocalizations are made such as squeaks. These can show they are threatened or be used during socialization.
Predators and Threats
Black rats are highly adaptable and with human expansion have benifited greatly by spreading to new areas.
In these areas they present a threat to native species such as birds which they feed on the eggs of and become a food competitor for.
They have a number of common names including the house rat, Alexandrine rat, old English rat, ship rat or roof rat.
Black rats are known to carry a number of diseases which can infect humans such as listeria, salmonella and the black death (plague).
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By Kilessan – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9001055
By H. Zell – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8684146
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