POCKET MICE, KANGAROO RATS, AND KANGAROO MICE – Heteromyidae

POCKET MICE, KANGAROO RATS, AND KANGAROO MICE

POCKET MICE, KANGAROO RATS, AND KANGAROO MICE FACTS

Pocket mice, kangaroo rats, and kangaroo mice, sometimes called heteromyids (members of the family Heteromyidae), are small- to medium-sized rodents with external, fur-lined cheek pouches. The pouches open in front of the mouth and go back along the shoulders. They have fairly large eyes and short, rounded ears. Pocket mice use all four feet while walking, while kangaroo rats and mice use only their rear two feet for walking. Kangaroo rats and mice have long tails with white tips or tufts on the end, along with relatively short front limbs. Pocket mice have shorter, less noticeable tails. Kangaroo rats and mice have good hearing. Kangaroo rats and mice have soft and silky fur, while pocket mice have coats that range from silky to spiny. The coat color varies from light to dark, depending on species and habitat, often matching the soil color on which they live.

Adults are 1.7 to 14.6 inches (4.3 to 37 centimeters) long and weigh between 0.2 and 6.9 ounces (5 and 195 grams). Kangaroo rats weigh between 1.2 and 6.9 ounces (33 and 195 grams); kangaroo mice weigh between 0.4 and 0.6 ounces (10 and 17 grams); and pocket mice weigh between 0.2 and 3.0 ounces (5 and 85 grams).

GEOGRAPHIC RANGE

Heteromyids are found in the western United States, southwestern Canada, Mexico, Central America, and northern South America.

POCKET MICE, KANGAROO RATS, AND KANGAROO MICE HABITAT

Heteromyids live in deserts, dry grasslands, and, in a few cases, wet and dry tropical forests. Desert pocket mice and kangaroo rats like arid, dry, climates that contain sand, scrubs, sagebrush, grasses, and chaparral. Kangaroo mice prefer sandy habitats. In all cases, heteromyids like areas that contain many seeds.

POCKET MICE, KANGAROO RATS, AND KANGAROO MICE DIET

Heteromyids eat mostly seeds, but also eat green vegetation and, in some species, insects. Desert species can go without water for long periods of time. They leave their burrows at night to dig through soil with their forelimbs to gather seeds into their cheek pouches. When pouches are full, they return to one of their caches (KASH-uhz), hidden supply areas, which are used throughout the animal’s home range. Heteromyids defend their territory aggressively when they have collected many seeds.

BEHAVIOR AND REPRODUCTION

Heteromyids are nocturnal, active at night, rodents. Kangaroo rats and mice move about mostly by hopping on their hind limbs, while pocket mice use all four of their limbs in a walking motion. They have a very basic social structure, mostly living alone except for females and young. They do interact with nearby neighbors, which are often relatives. Most species burrow tunnel systems with multiple chambers and surface openings.

Heteromyids have well-developed communication systems. Medium- and large-sized kangaroo rats communicate by drumming or thumping the ground with their large hind feet; familiar thumping identifies neighbors, while strangers are not recognized. Each species has its own set of drumming patterns, which are heard through the air and ground.

Male home territories overlap with those of other males and females. Females occupy a territory that contains no other females. They regularly bathe in sand, which helps to clean their hair and to deposit their scents onto the ground. Their scent informs other heteromyids and other animals about their sex, identity and mating status. When a predator, an animal that hunts other animals, is seen, heteromyids use their body coloring to hide and avoid them. If needed, they will run away along a crooked path. Desert heteromyids also have strong hearing that lets them hear approaching predators.

Males always travel to female territories during breeding season in order to mate. Mating relationships range from one male and one female, to several males competing for access to one breeding female. Larger and medium sized kangaroo rats drum their feet in order to chase away competing males. Females prefer to mate with males they know, but will mate with strangers if necessary. Males will mate with any females. Breeding occurs only when enough moisture is available for nursing females to provide milk to young. Females produce several litters, group of young animals born at same time from the same mother, each year, but the number depends on environmental conditions. Litter sizes range from one to nine, but average three to four in most species. They live ten years or longer.

POCKET MICE, KANGAROO RATS, KANGAROO MICE,  AND PEOPLE

Kangaroo rats are considered keystone species because their burrows provide habitat for a variety of plants and animals. A keystone species is a species that is important in maintaining the biodiversity, the variety of different animals and plants, of an area.

CONSERVATION STATUS

Four species of pocket mice, kangaroo rats, and kangaroo mice are listed by the World Conservation Union (IUCN) as Critically Endangered, facing an extremely high risk of extinction in the wild. One species is listed as Endangered, facing a very high risk of extinction in the wild, and one species is Vulnerable, facing a high risk of extinction. The IUCN also lists nine species as Near Threatened, not currently threatened, but could become so. Many species are threatened with excessive destruction and fragmentation, breaking up, of habitat and the loss of plant life.