Those familiar to humans are the black rat and the brown rat. They may however be confused with mice. Well, they can be distinguished by their size difference. Mice are generally larger, but not so big, than the mice.

The brown rat, commonly known as the street rat, lives in areas such as sewers and around urban areas. These animals will always be seen as close to human settlements as possible, and rarely in the wild. This is due to their feeding characteristic, which is scavenging through garbage for their preferred dietary food, cereal leftovers.



Averagely, the brown rat will grow up to a range of 20 to 25 cm long, excluding the tail which may grow up to between 18 and 25 cm long. This implies that the tail is roughly same as its body in length. The average body weight range of an adult brown rat is 220g to 330g, and may plumage to up to 1kg. These cases are however very rare and can only occur if the rat is kept as a pet or used in the laboratory for experiments.

Male brown rats record a higher body weight number as compared to their female counterparts. An average male will weigh up to 350g while a female will weigh up to 250g respectively. This disputes the mythical facts that rats can grow as big as cat; they can be big but not that big. In fact, breeding rats will averagely weigh less than 300g.

With the ability to breed all year round, they have a gestation period of 21 days, producing up to 5 litters a year and an average of 7 per litter. The female sometimes divides the young ones and takes turn to feed them in case the litter is too large. The tiny rats take about 5 weeks to reach sexual maturity making the mother available to reproduce again. In some cases, the mother can get pregnant almost immediately after giving. She will continue weaning the young litter till birth of another litter. At this rate, the population of rats can grow from 2 to 1500 in just a year.

The black rat, also known as the house rat, is a generalist as it does not have a food preference. The feed ranges from fruits nuts, cereals, cow feeds, milk and cocoa among others. These home invaders however, prefer foraging at night. Unlike the brown rats as stated earlier, these rats are smaller in body structure. A typical black rat will weigh between 75 and 230g, with a body length of between 12 and 19cm and a tail which ranges from 15 to 22 cm long. Their young ones are very tiny.

Read the How to get rid of rats page for helpful information and to learn more about How big do rats get?

How big do rats get?