Black Rat
Rattus rattus is now found throughout the world as a human commensal. It was probably native to Asia. Rattus rattus occupies cities, villages, cultivated fields, and many undisturbed habitats. They shelter in nests built in trees, roofs, or other elevated positions.
Black Rat (Roof Rat, Ship Rat)
Rattus rattus have a uniformly colored dorsal side, usually black to tawny brown. The underbody is paler, lighter brown or slate colored. The tail is longer than the head and body, sparsely haired and scaled. These rats are typically 18-22 cm long, with a tail approximately 18.5-24 cm in length. Adapted for climbing and living in high places, the feet retain all of the digits, with a rudimentary pollex
Reproduction
Rattus rattus have a high reproductive potential. The breeding season lasts all year. Under normal conditions, females have between three and seven litters per year. The average litter size is between six and twenty-two young. The gestation period lasts twenty-two days in nonlactating females and twenty-three to twenty-nine days in lactating females. Young weigh four to five grams at birth, and are born blind, naked, helpless, and wholly dependent on the parent for several days. The young open their eyes around the fifteenth day of life. Weaning occurs at three to four weeks. Sexual maturity is reached at about eighty days.
Behavior
The black rat is active at dusk and during the night. Having a history of dependence on man, living in human communities, and competing with man for food may have led, by natural selection, to changes in behavior related to coexistence with humans. Rattus rattus, for example, display avoidance of unfamiliar objects such as traps. Living in trees or roofs, R. rattus tend to flee upward. These do not burrow or swim but climb and nest above ground. They construct a loose, spherical nest of shredded vegetation, cloth, or other suitable material. The black rat is a territorial, sociable animal, sometimes forming clans of up to sixty animals. Social groups usually contain a single dominant male and sometimes a linear male hierarchy. There are also two or three top females, subordinate to the males but dominant to the rest of the group. Females display more aggressive behavior than males. The feeding territory is defended against outsiders by biting, jumping, and standing on hind legs and hitting with the front paws. The infants in the group have immunity from aggression and can take food from the dominant adults.
Food Habits
Rattus rattus are omnivorous. They eat seeds, nuts, vegetables, fruits, insects, invertebrates, and other materials such as soap, paper, hides, and beeswax. Food may be carried back to the nest and stored. In captivity they should be offered a complete diet of rodent lab blocks, and rat or mouse mix, with bits of fruit or veggies regularly. Cheerios or wheat bread are great treats, in small quantities. Do NOT feed chocolate, fried foods, salted foods, candy or junk food! They may enjoy crickets and mealworms if they are captive bred, never feed wild insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium during nursing and growth due to demands on their systems at those times, but take care not to overdo it. Water bottles should be used to proved constant, clean water. Ceramic or stoneware food dishes work well for keeping seeds or fresh foods off the floor, and a wire mesh hopper that allows them to eat the lab blocks through without extra waste.
