Ship rat, Roof rat, Trodman, House rat, Alexandrine rat, Old English rat
The Black rat (otherwise called the Ship rat) has a hairless and extremely long tail that is longer than their head and body. Romans were the ones who introduced this species to Britain. As a matter of fact, the coat of the Black rat varies from black to grey-brown. As compared to Brown rats, these animals have smaller body and larger ears and eyes. The Black rats are accomplished climbers. They are capable of running along telephone wires, using their tails to balance while moving. The species is also called 'Roof rat' due to constructing their nests high in roof spaces.
These rats are widely distributed around the globe, occurring on all continents. The Black rat is thought to be a native Indian and Indo-Malayan species. In course of time, however, it has been introduced to all continents due to human travel. Since these animals are found through human sea faring, they most frequently occur in coastal areas. As accomplished climbers, the Ship rats are able to live in top floors of buildings in urban areas and tall trees in forests.
Black rats are normally nocturnal. However, those in undisturbed areas tend to be active during the daytime hours. These rats are highly social animals, forming 'packs' - groups of two or more dominant females and several males, one of which is dominant. These females lead the pack and dominate all members of the group. Meanwhile, the dominant male doesn't submit to them and often forms a separate linear male hierarchy. Female rats are considerably more aggressive than males. These animals often construct their nests in burrows, making them out of sticks and leaves. The Black rats can be either arboreal or terricolous, depending on geographical location. They are excellent climbers, due to which those living in urban areas can make their homes high in upper floors of buildings. Individuals within the pack establish dominance through aggressive threat postures and physical contact. These rats are also very vocal animals: they are known to give out squeaking sounds when threatened or when communicating with conspecifics. They leave oil marks in order to define territorial boundaries. The Black rats also have developed senses of vision, hearing, touch, and smell.
The Ship rats have a polygynous mating system, where a single male mates with a number of females. Usually, the dominant male is the most successful breeder. These rats mate from March to November. Gestation period lasts for 21 - 29 days, yielding 3 - 5 litters of 1 - 16 young (with an average of 7) per year. Babies of this species are born altricial. Their eyes open only at 15 days old, while hairs appear by the end of the nursing period. The young are weaned, gaining independence at 3 - 4 years old. Females become sexually mature at 3 - 5 months old.
The Black rats are killed by people as pests. In addition, these animals are very dangerous to humans. As pests, they are known to consume crops, destroying farms and fruit trees. Furthermore, they simply destroy what they don't eat. The 'Black Death' or bubonic plague, which took millions of human lives in the medieval times, was spread by the Black rats. This is largely due to fleas on their body, which carry multiple diseases that are extremely dangerous for humans and livestock.
According to IUCN, the Black rat is abundant and widespread throughout its range but no overall population estimate is available. However, according to the People’s Trust for Endangered Species resource, Great Britain population size is around 1,300 individuals, including up to 1,000 individuals on the Shiant Islands, Hebrides. Overall, Black rats’ numbers are stable today, and the species is classified as Least Concern (LC) on the IUCN Red List.
The Black rat has a rather negative impact on the local ecosystem: this animal has become the reason of the extinction of numerous birds, small mammals, reptiles, invertebrates as well as plants, particularly on islands.