Black rat

Rattus rattus

TAXONOMY

Rattus rattus (Linnaeus, 1758), Uppsala, Sweden. OTHER COMMON NAMES

English: House rat, ship rat; French: Rat noir, rat commun; German: Hausratte; Spanish: Rata de los techos, rata común.

PHYSICAL CHARACTERISTICS

Body length 6.3-8.6 in (16-22 cm); tail 6.7-9.8 in (17-25 cm); weight (70-300 g). Its tail is always longer than its relatively slender body, and it has very large ears. Several subspecies exist, with various colorings: one has black fur on the top and gray fur on the bottom of the animal; one is agouti above and white below; and one is agouti above and slate below. The animal occasionally has a white spot on its chest.

DISTRIBUTION

Has spread throughout the world, though it is likely native to peninsular India.

HABITAT

Found around the world because they tended to become stowaways on ships, it is believed that more than 90% of rats on ships were black rats. They have been found in fruit plantations, palm trees, or bushes, either in conical nests or burrows. Black rats in the modern era tend to inhabit the upper stories of wooden buildings, leading some to speculate that the observed decline in parts of Europe may have to do with the gradual disappearance of wooden buildings. But they are a hardy species, and now take refuge in sewers or cellars or even in trees in parts of Europe.

BEHAVIOR

These mostly nocturnal rats have used their climbing skills to their advantage, by traveling along power lines and cables to spread from house to house. They are highly social creatures, which travel in packs, sleep in piles, and when they meet, they crawl beneath one another. They also can be territorial and display various postures similar to other animals in the genus, including the threat posture, a hunched, hair-bristled pose that aggressive individuals assume to display animosity.

FEEDING ECOLOGY AND DIET

Primarily vegetarians, feeding on fruit and seeds, but will eat insects and other invertebrates if necessary.

REPRODUCTIVE BIOLOGY

Polygamous. Breed year-round in conducive habitats, producing up to five litters per year. The females, which have 12 nipples, give birth to litters consisting of between 6-12 young, with the average litter size being eight. Young open their eyes at 15 days of age.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS

Have been closely tied with humans for thousands of years, and are vermin-infested creatures responsible for spreading various diseases to humans, including the bubonic plague that swept Europe in the fourteenth century and various other eras. The rats harbor fleas, which, after biting the rat, can transfer the bacteria responsible for the plague to humans. Black rats, especially those in tropical climates, still spread the bubonic plague. The animals are known to strip the bark off of trees and they tend to infiltrate food caches and eat anything people have tried to store, including grains, seeds, cereals, and fruits. The main predator of the black rat is the house cat. ♦

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