|Gray , 1841|
The kangaroo rats or pocket jumpers ( Dipodomys ) represent a genus of the pocket mice (Heteromyinae) within the rodents (Rodentia). They live mainly in the desert and semi-desert areas of the southwestern USA and Mexico . They owe their name to their mode of locomotion on two legs, which is reminiscent of the kangaroos . However, they should not be confused with rat kangaroos .
There are 21 types of kangaroo rats, the length of the head body varies between 100 and 200 millimeters, whereby the tail is usually just as long or a little longer. The weight varies between 35 and 180 grams. The most noticeable feature of the kangaroo rats are the greatly elongated hind legs that are designed to form jump legs. Most kangaroo rats are matched in their coat color to the desert color, accordingly it varies between a light and a darker brown, the belly side is almost always light. In addition, there are often white stripes on the hips. The tail is usually dark and ends in a tassel made of longer hair.
Way of life
Like the gerbils ( jaculus ) in the deserts of Africa and Asia or the jerbos ( Antecinomays ) in the Australian outback , the kangaroo rats are extremely well adapted to life in the desert. They live in deep earthworks, where they are safe from the greatest heat, and rarely need water. The latter is made possible by an efficient hydrogen exchange, very efficient kidneys and the possibility of obtaining water from your food through biochemical processes. By cooling the exhaled air, water is also retained in the body. As the animal exhales, the air is cooled on the less perfused and therefore cooler nasal mucosa. As a result, the air can hold less moisture and water condenses. This is also used as a cooling mechanism. The enlarged hind legs are also found in all three groups and have been developed convergently .
Kangaroo rats live on seeds, leaves, stem tissue, fruits and other parts of the sparse vegetation of their home; they also hunt insects . Many species also build storage rooms in their caves for dry seasons. For example, a store of six kilograms of forage plants was found in a burrow of the Dipodomys spectabilis (English Bannertail Kangaroo Council). As pocket mice , the kangaroo rats have large cheek pouches in which they can transport food or nesting material. The cheek pouches are emptied using special muscles that enable the "containers" to be turned inside out and then reshaped. In some species there is a territory marking through the droppings and all species have scent glands on the shoulders.
Some species (e.g. the flag-tailed kangaroo rat) have a circalunar rhythm. They only come out of their burrows when looking for food at the new moon, so as not to be seen by their enemies (coyotes, owls), who hunt better when the moon is shining. This rhythm is kept from November to March. If the food reserves in their burrows become scarce, the animals begin to look for food later in the day, even in the moonlight.
A distinction is usually made between the following 21 types:
- Ord kangaroo rat ( Dipodomys ordii ), western North America
- Gulf Coast Kangaroo Rat ( Dipodomys compactus ), south Texas , northeast Mexico
- Chisel-toothed kangaroo rat ( Dipodomys microps ), American midwest
- Panamint kangaroo ( Dipodomys panamintinus ), California , Nevada
- Stephens kangaroo rat ( Dipodomys stephensi ), southwest. California
- Big-eared kangaroo rat ( Dipodomys elephantinus ), central California
- Santa Cruz kangaroo rat ( Dipodomys venustus ), western California
- Pacific kangaroo rat ( Dipodomys agilis ), southwest. California
- Heermann's kangaroo rat ( Dipodomys heermanni ), central California
- California kangaroo rat ( Dipodomys californicus ), northern California, Oregon
- San Quintin kangaroo rat ( Dipodomys gravipes ), Baja California
- Giant kangaroo rat ( Dipodomys ingens ), central California
- Flag-tailed kangaroo rat ( Dipodomys spectabilis ), Arizona , New Mexico , western Texas, northern Mexico
- Nelson's kangaroo rat ( Dipodomys nelsoni ), north-central Mexico
- Texas kangaroo rat ( Dipodomys elator ), Texas, Oklahoma
- Phillips' kangaroo rat ( Dipodomys phillipsii ), central Mexico
- Merriam's kangaroo rat ( Dipodomys merriami ), southwest. USA, northern Mexico
- San Jose kangaroo rat ( Dipodomys insularis ), Isla San José (Mexico)
- Margarita kangaroo rat ( Dipodomys margaritae ), Isla Santa Margarita (Mexico)
- Fresno kangaroo rat ( Dipodomys nitratoides ), central California
- Desert kangaroo rat ( Dipodomys deserti ), southwest. USA, northwest Mexico
Kangaroo rats and humans
Kangaroo rats tend to be common. They often live near grain fields and can cause some damage there, but this is minor compared to some other rodents. Some species of kangaroo rats became extinct through direct or indirect human influences. The chisel-toothed kangaroo rat and Merriam's kangaroo rat live geographically in the same range, but the former, being the slower species, requires habitats with dense shrub growth, while the faster Merriams kangaroo-rat lives in open terrain. In large regions of the Midwest, the clearing of the shrubbery has led to the extermination of the chisel-tooth kangaroo rat, whereas Merriam's kangaroo rat is taking advantage of the situation and is spreading explosively.
The IUCN lists four species as threatened or critically endangered. The San Quintin kangaroo rat, which only lives in a small coastal strip of Lower California and has become very rare due to the agricultural use of its habitat, has the status “threatened”. The following three species are even considered "critically endangered": the giant kangaroo rat, endemic to the San Joaquin Valley of California; the San Jose and Margarita kangaroo rats, both of which are native to small islands in the Gulf of California .
In addition, the following subspecies of kangaroo rat species are threatened or extinct:
- Dipodomys microps russeolus , endemic to Dolphin Island in the Great Salt Lake , died out in the 1940s when the island was flooded as a result of drastic water level fluctuations
- Dipodomys microps alfredi lives or lived on Gunnison Island, also in the Great Salt Lake; probably also extinct
- Dipodomys heermanni morroensis , confined to a coastal strip on Morro Bay, California, is now severely threatened by human colonization on the coast
- Dipodomys nitratoides nitratoides and Dipodomys nitratoides exilis , like the giant kangaroo rat, are endemics of the San Joaquin Valley and both are endangered
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes, 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
- Jan A. Randall: Vibrational Communication: Spiders to Kangaroo Rats. In: G. Witzany (Ed.): Biocommunication of Animals. Springer, Dordrecht 2014, ISBN 978-94-007-7413-1 , pp. 103-133.