Predators of Dipodomys merriami include rattlesnakes, coyotes, weasels, owls, and predatory birds ( Grzimek, 1990 ). D. merriami have the ability to efficiently use the water from their food, and they neither sweat nor pant to keep cool. They have specialized kidneys which allow them to dispose of waste material with very little output of water. This allows them to live comfortably in arid areas ( http://www.desert.usa.com ).
Perception Channels: tactile ; chemical
The subspecies Dipodomys merriami parvus (San Bernardino Merriam's kangaroo rat) is considered endangered under the U.S. Endangered Species Act. Several factors contribute to this, including predation and habitat reduction resulting from agricultural development, urbanization, and road-building. Flooding has also been a contributing factor. The only known method for conserving the kangaroo rat is through habitat preservation. The U.S. Fish and Wildlife Agency, together with the State of California and other wildlife agencies have purchased thousands of acres of habitat to try and protect these animals. This is a slow project because recovery plans are expensive ( http://www.hillsborough.k12.nj.us/hhs/endspeci/KANGARAT.HTM ).
San Bernardino Merriam's kangaroo rats (Dipodomys merriami parvus and Earthquake Valley kangaroo rats (Dipodomys merriami collinus), which both occur near the Los Angeles and San Diego urban areas, are considered data deficient by the IUCN.
Other subspecies of D. merriami are not considered threatened currently.
US Federal List: endangered; no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
As seed predators they may affect plant populations, but they are rare in agricultural areas.
Dipodomys merriami are important in dispersing seeds of plants in arid regions. Their burrowing and digging is thought to aerate and fertilize soil. (www.desert.usa.com/aug96/du_krat.html )
The diet of the Merriam's kangaroo rat is almost entirely seeds. They feed primarily on the seeds of mesquite, creosote bush, ocotillo, purslane, and grama grass. One study of D. merriami showed that seeds make up 64% of the diet, with seeds of shrubs consituting 23%, forbs 24%, those of grasses 4.5%, and those of scculent plants 12%. ( http://www.nsrl.ttu.edu/tmot/dipoerr.htm ). The diet is diverse and varies seasonally. Insects are eaten occasionally. They are eaten in the greatest abundance in the winter months, while green vegetation is eaten most during the mid-summer months
Dipodomys merriami, Merriam's kangaroo rat, is a rodent found in the arid regions of the southwest United States and Mexico.
Biogeographic Regions: nearctic (Native )
Dipodomys merriami are sand-dwelling mammals that inhabit arid regions of the southwestern United States and Mexico. Habitat requirements of Merriam's kangaroo rats are less strict than most other species of kangaroo rats. They can live equally well in sandy soils, clays, gravels, and among rocks. (www.nsrl.ttu.edu/tmot/dipomerr.htm ). Compared to other kangaroo rats, Dipodomys merriami inhabits harder, stonier soils.
Terrestrial Biomes: desert or dune
Range lifespan
Status: captivity: 9.7 (high) years.
Merriam's kangaroo rats have an average total length of 247 mm. The tail is rather long, about 144 mm in length, with an end tassle. It is usually more than 130% of the the length of the head and body. ( http://www.nsrl.ttu.edu/tmot/dipomerr.htm ). The body is covered with dusky stripes which run the length of the head and body. The skull is sciuromorphous with dramatically inflated auditory bullae. The face is covered with dark facial markings. D. merriami also has fur lined external cheek pouches which it carries seeds in. The belly of Merriam's kangaroo rat bears white, silky pelage. The hind feet, bearing four toes, are very large, (39 mm), with hairy soles. These hairy soles aid the kangaroo rat in jumping through loose sand. The forelegs are retrogressed. The ears are small and hairless, and the eyes are large and luminous, similar to the eyes of other nocturnal mammals. The dental formula is 1/1, 0/0, 1/1, 3/3 = 20. ( Vaughn, 1999 ).
Range mass: 40 to 50 g.
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 0.246 W.
Dipodomys merriami has a high reproductive rate. Breeding for the Merriam's kangaroo rat begins in early February and continues into the spring, at least through May. The gestation period is approximately 28 to 32 days. Between one and six young are born in each litter, with an average of three. When young are born they weigh between 3 and 8 grams. The young are weaned after 15-25 days, and sexual maturity is reached between 60-84 days. They can live up to 9.8 years. Average territory size for males is 67,300 square feet, less than one acre. Average female territories are 4000 square feet. (Grzimek, 1990, www.desert.usa.com/aug96/du_krat.html )
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 2.92 g.
Average gestation period: 28 days.
Average number of offspring: 2.3.
Average age at sexual or reproductive maturity (female)
Sex: female: 102 days.
Merriam's kangaroo rat (Dipodomys merriami) is a species of rodent in the family Heteromyidae.[2] The species name commemorates Clinton Hart Merriam. It is found in the Upper and Lower Sonoran life zones of the southwestern United States, Baja California, and northern Mexico.
Merriam's kangaroo rats, like other kangaroo rats and pocket mice, are members of the family Heteromyidae. Each species within this family has fur-lined food storage pouches. The cheek pouch is utilized as a portable cache for food while foraging. Kangaroo rats are named for their extremely long, kangaroo-like hind feet and they are almost completely bipedal. They hop or jump rather than scurry or run. Because of this, most heteromyid rodents also have a relatively long tail that acts to counterbalance the hopping/jumping form of locomotion.
Fur color varies between populations within the species' range, but the back color is generally light brown or tan. The merriami species is smaller than most of the other kangaroo rats in the southwest. Adults average about 14 inches in length. The tail is relatively long with a large tuft of hair at the tip. The tuft is thought to act like fletching on an arrow, providing drag to keep the animal stable during locomotion. merriami have four toes on each hind foot in contrast to the pacific kangaroo rat, Dipodomys simulans and the Stephens' kangaroo rat, Dipodomys stephensi (both kangaroo rat species also found in San Diego County), which have five toes.
Merriam's kangaroo rat can be found in desert scrub, alkali scrub, sagebrush steppe, pinyon-juniper woodland, and Joshua tree habitat throughout the southwestern United States and Mexico.[3]
Merriam's kangaroo rats live individually within a maze of burrows. Males and females each establish individual territories. They defend their territories against other male and female merriami, primarily to protect often scarce food resources. It is typical that they locate multiple entrances to their burrow complex at the base of shrubs near the middle of their territory. This allows more opportunities for them to escape from predators.
Most kangaroo rats are exclusively nocturnal. Even so, they tend to avoid being outside their burrows when the moon is full. The greater the amounts of moonlight the less time they spend collecting food, defending their territory, or searching for mates. When the amount of moonlight is great they retreat underground in order to avoid predation. In some areas, above ground activity is limited to two hours or less.[3] During the day, they remain in their cool burrows. They often seal entrances to their burrows with soil to prevent exposure to heat. When they are active above ground they move about within their territory and attempt to fill their cheek pouches with seeds and plant material. When their cheek pouches are full they retreat to their burrows where they disgorge the seeds they have collected. Some of the food is eaten immediately while the remainder is stored (often building a seed cache of considerable size) in several chambers within the burrow system.
Kangaroo rats lose water mainly by evaporation during gas exchange, and so have developed a behavioural adaptation to prevent this loss. As they spend a lot of time within their burrows to escape the heat of the day, the burrows become much more humid than the air outside (due to evaporative loss). When collecting seeds, they store them in the burrows rather than eating them straight away. This causes the moisture in the air to be absorbed by the seeds, and the kangaroo rat regains the water it has previously lost when it then consumes them.
Merriam's kangaroo rats produce up to three litters per year, with an average of four pups in each litter. Weaning of young occurs 24–33 days after birth.[4]
The diet of Merriam's kangaroo rat is almost exclusively plant seeds (they are granivorous). The bulk of their diet consists of the seeds of desert and grassland plants. They rarely drink water. Rather, they obtain water through metabolic processes augmented by the moisture content of their food.
Kangaroo rats are a common prey items for many other desert animals. Typical predators of the Merriam's kangaroo rat include barn owls, great horned owls, coyotes, foxes, badgers, bobcats, and several snake species including sidewinders and glossy snakes. Cougars and American black bears are known to prey on kangaroo rats when they encounter them, although both predators typically prefer larger prey to sustain themselves.
In general humans have not caused adverse impact to the Merriam's kangaroo rat through most of its range. However, in southern California one subspecies, the San Bernardino kangaroo rat, Dipodomys merriami parvus, is at risk due primarily to urban development including construction of dams and alteration of hydrologic regimes throughout its range. Once common on alluvial plains in the washes of San Bernardino and Riverside counties, the United States Fish and Wildlife Service listed the San Bernardino kangaroo rat as endangered in 1998.
Merriam's kangaroo rat (Dipodomys merriami) is a species of rodent in the family Heteromyidae. The species name commemorates Clinton Hart Merriam. It is found in the Upper and Lower Sonoran life zones of the southwestern United States, Baja California, and northern Mexico.
