Litter Size

How many babies does a Brown rat have at once? (litter size)

How many baby Brown rats are in a litter?

A Brown rat (Rattus norvegicus) usually gives birth to around 8 babies.With 3 litters per year, that sums up to a yearly offspring of 24 babies.

Each of those little ones spend around 21 days as a fetus before they are released into the wild. Upon birth, they weight 5 grams (0.01 lbs) and measure 5.2 cm (0′ 3″). They are a member of the Muridae family (genus: Rattus). An adult Brown rat grows up to a size of 18.2 cm (0′ 8″).

To have a reference: Humans obviously usually have a litter size of one ;). Their babies are in the womb of their mother for 280 days (40 weeks) and reach an average size of 1.65m (5′ 5″). They weight in at 62 kg (137 lbs), which is obviously highly individual, and reach an average age of 75 years.

The average litter size of a Brown rat is 8

The brown rat (Rattus norvegicus), also known as the common rat, street rat, sewer rat, Hanover rat, Norway rat, Norwegian rat, Parisian rat, or wharf rat is one of the best known and most common rats.One of the largest muroids, it is a brown or grey rodent with a head and body length of up to 28 cm (11 in) long, and a tail slightly shorter than that. It weighs between 140 and 500 g (5 and 17 3⁄4 oz). Thought to have originated in northern China, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America, making it, by at least this particular definition, the most successful mammal on the planet alongside humans. With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas.Selective breeding of the brown rat has produced the fancy rat as a pet, as well as the laboratory rat – rats used as model organisms in biological research.

Other animals of the family Muridae

Brown rat is a member of the Muridae, as are these animals:

Animals that share a litter size with Brown rat

Those animals also give birth to 8 babies at once:

Animals with the same weight as a Brown rat

What other animals weight around 282 grams (0.62 lbs)?