The Fresno kangaroo rat or San Joaquin kangaroo rat (''Dipodomys nitratoides'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

in the family

Heteromyidae Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within th ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to areas within and near the

San Joaquin Valley The San Joaquin Valley ( ; es, Valle de San Joaquín) is the area of the Central Valley of the U.S. state of California that lies south of the Sacramento–San Joaquin River Delta and is drained by the San Joaquin River. It comprises seven ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

Habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

due to agricultural development and urbanization has put this species at risk, and the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

has assessed its conservation status as " vulnerable". There are three subspecies of ''D. nitratoides'': * ''D. n. exilis'' (Fresno subspecies), * ''D. n. nitratoides'' (Tipton subspecies), * ''D. n. brevinasus'' (short-nose subspecies).

Description

The Fresno kangaroo rat is the smallest of the kangaroo rats in its genus, and has a head-and body length of about . Like other members of the genus, its tail, which is tipped with a large tuft of fur, is longer than the head and body combined. Kangaroo rats do not run, but use their powerful hind limbs to jump as in the manner of a kangaroo, using their tails for balance as they proceed in bounds. The small front legs are used for manipulating food. The fur of the upper parts of this species is yellowish and that of the underparts is white.

Distribution and habitat

This

kangaroo rat Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed t ...

is found in and around the

, in the

. The subspecies ''D. n. exilis'' and ''D. n. nitratoides'' are found only in the valley bottom. Historically, ''D. n. exilis'' occupied alkaline grassland and saltbush scrub between

Merced River The Merced River (), in the central part of the U.S. state of California, is a -long tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through th ...

to the north and Kings River to the south, and between

Fresno Slough Fresno Slough is a distributary of the Kings River that connects the North Fork Kings River to the San Joaquin River in San Joaquin Valley, Kings County, California. Until 1879 when irrigation diversions prevented it, Fresno Slough was also an ou ...

to the west and

Fresno Fresno () is a major city in the San Joaquin Valley of California, United States. It is the county seat of Fresno County and the largest city in the greater Central Valley region. It covers about and had a population of 542,107 in 2020, maki ...

to the east. This area of occupancy has shrunk and now covers an area of about in

Fresno County Fresno County (), officially the County of Fresno, is a county located in the central portion of the U.S. state of California. As of the 2020 Census, the population was 1,008,654. The county seat is Fresno, the fifth-most populous city in Cali ...

to the west of Kerman. Similarly, the range of ''D. n. nitratoides'' has shrunk from most of the Tulare Basin to some fragmentary patches surrounded by cultivated land in northern Kings County and southern

Kern County Kern County is a county located in the U.S. state of California. As of the 2020 census, the population was 909,235. Its county seat is Bakersfield. Kern County comprises the Bakersfield, California, Metropolitan statistical area. The county sp ...

, to the east of the dried up

Tulare Lake Tulare Lake () ( Spanish: ''Laguna de Tache'', Yokuts: ''Pah-áh-su'') is a freshwater dry lake with residual wetlands and marshes in the southern San Joaquin Valley, California, United States. After Lake Cahuilla disappeared in the 17th century ...

. The subspecies with the most extensive range is ''D. n. brevinasus''; this inhabits grasslands and shrublands on the foothill slopes to the west of the San Joachim Valley, from Merced County in the north to

San Emigdio Creek San Emigdio Creek, formerly Arroyo de San Emigdio (Spanish for Saint Emygdius Creek), is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed September 7, 2011 northward-flowing stream in ...

in the south, and the foothills to the east of the San Joachim Valley near the dried up

Buena Vista Lake Buena Vista Lake was a fresh-water lake in Kern County, California, in the Tulare Lake Basin in the southern San Joaquin Valley, California. Buena Vista Lake was the second largest of several similar lakes in the Tulare Lake basin, and was fed ...

Ecology

The species is nocturnal and shows maximum activity levels shortly after sunset. It is three times less active on nights with a moon than on moonless nights; it is more active in the open on nights without a moon, while keeping in the shade of vegetation when the moon is shining. It feeds largely on seeds which it stuffs into its cheek pouches for transporting back to the burrow to eat or to cache. It chooses friable soil for the digging of the burrow. Breeding may take place three times a year, with litters of up to five young, and the gestation period is about one month.

Status

The Fresno kangaroo rat is limited to a range of about , a much smaller area than it used at one time to occupy. Much of its traditional range has been converted for agricultural use, some has been used for infrastructure projects and some for urban development. It does not adapt well to cultivated fields, though it may re-invade them if they are abandoned. It is rather patchy in occurrence, with large swings in its total population, due to flooding, drought or other occurrences. This may lead to local extirpation, and with the fragmentation of its range, populations do not easily recover. For these reasons, the

has assessed its conservation status as " vulnerable". The subspecies most at risk is ''D. n. exilis'' which now has a total area of occupancy of only . Some populations of ''D. n. nitratoides'' have fewer than 50 individuals and occupy such restricted habitats as the central strip of highways.

References

External links

Endangered Species Recovery Program species information page
{{Taxonbar, from=Q303570 Fresno Kangaroo Rat