The Napa black rat (rattus rattus) also known as the roof rat or house rat, is the most common of the rodents that we come into contact with. As it is an omnivore, it will eat anything in order to survive. The California black rat is found mainly in warmer areas. It is nocturnal, which means that it will mainly be scurrying around your home while you are sleeping. This means that unless there are dropping or obvious gnaw marks, it can be there for months before you even notice.



Appearance
A typical adult California rat is between 5 – 8 inches long. It varies in color from black to light brown, with a lighter belly. It is slender and has large, mostly hairless ears. The tail in hairless and only one color, it is always longer than the head and body combined (between 6 – 9 inches long.) it usually weighs between 120 – 160 g, but has been known to weigh over 200g.

Diet
Black rats are omnivores, which means that they eat anything that they are able to procure in their environment. This leads to major problems for farmers because they will eat everything from seeds, fruit, animal products, or anything else that is found in the vicinity. They are essentially scavengers and will eat whatever they can find. When they are found in cities, they are not above eating your pet’s food that is left outside. They will also come into your house if there is trash that has not been properly disposed of, and make a meal of it. They have been known to eat as much as 15g of food per day.

Reproduction
Breeding takes place during March and November, with an average of 7 babies being produced per litter. Females can give birth to up to 5 litters per year. The intervals between litters can be as short as 27 days. Black rats are mature at three weeks old and can reproduce at three months of age. They usually live around a year in the wild, but can live up to four years in captivity.

Habitat
Black rats are native to India, they are believed to have been spread aboard the ships of explorers and have since spread all over the world. Thus, they are also called California ship rats. They are more prevalent in warmer, tropical climates and areas that are close to the ocean. They are very agile and easily live in areas where they are able to nest high up in trees or in buildings.

Visit our Napa wildlife control home page to learn more about us.