New World rats and mice

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New World Rats and Mice
Temporal range: Late Miocene - Recent
Sigmodon hispidus1.jpg
Sigmodon hispidus
Scientific classification
in part


The New World rats and mice are a group of rodents from the family Cricetidae. They are mammals with fur and long tails. These animals live in the wild in North and South America. The group is very large, with about 500 different species. Biologists are not sure whether the group is descended from a common ancestor, so there is no scientific name for it. There are three subfamilies, Neotominae, Sigmodontinae and Tylomyinae.

Members of the New World rats and mice have occupied different ecological niches. Because of this, they have developed different forms. Most of them resemble rats or mice in appearance, but some look like voles, moles, gerbils or shrews. The biggest of them are Kunsia, with about 16–30 cm body length, and about 8–16 cm tail. Among the smallest are Baiomys, with about 5–8 cm body length, and about 5 cm tail.

Most of the New World rats and mice live on the ground, but are good climbers. Some live in trees. Others dig holes in the ground, or live part of their life in the water. New world rats and mice do not hibernate, but on cold days in winter, they sometimes fall into a torpor.

The New World rats and mice have many predators, and usually live only a short time. In the wild, these animals usually live for less than a year, but they have reached ages of up to five years old when kept indoors and protected by people. Some species have adapted to humans, and are hemerophile. This has also shown in some common names, such as the Cotton rat, Marsh rice rat, Brown Cane Mouse or Short-tailed Cane Mouse.