The San Joaquin kangaroo rat lives in a dry desert environment and, as a result, has evolved to survive without relying on drinking water, instead obtaining the water it needs from its food (2) (3) (4). It produces very concentrated urine and dry faeces, which helps to reduce water loss (4). Like other kangaroo rats, the San Joaquin kangaroo rat requires sand or fine silt in which to ‘dust bathe’, to keep its fur in good condition (2).
Kangaroo rats hop on their hind legs in a similar fashion to kangaroos, only occasionally using the front legs for walking (2) (3). The long tail is used for balance (5), and the tip of the tail is held up while the kangaroo rat is moving (2). The San Joaquin kangaroo rat is nocturnal and does not hibernate, instead remaining active year-round (2) (3) (5).
The San Joaquin kangaroo rat makes its home in a burrow in the ground, usually dug at the base of a low bush, often in a slightly raised area (1) (3) (5). The burrow may occupy an area around two to three metres across, and has several openings, one or two of which are used as escape routes (3) (5). The San Joaquin kangaroo rat is solitary and territorial, with only one adult occupying each burrow system (2) (3). This species may communicate by drumming its hind feet on the ground (2), or through scent from the secretions from a conspicuous gland on its back (4).
The diet of the San Joaquin kangaroo rat mainly consists of the seeds of annually flowering plants and shrubs. Grasses and herbs that grow due to early rains in the spring are also a food source (1) (2) (3) (5), and this species also occasionally eats insects (1) (2) (5). The somewhat damp conditions inside the burrow may prevent the San Joaquin kangaroo rat from storing food underground through part of the year, but it is known to cache seeds in small pits in the burrow walls or on the surface of the soil (1) (2) (3) (5). The San Joaquin kangaroo rat has fur-lined pouches in its cheeks which it can use to carry food (4) (5).
In the wild, the breeding season of the San Joaquin kangaroo rat typically runs from December to August, but this species is also known to breed throughout the year (2) (3). The gestation period lasts only 32 days, and the young are born in the underground burrow (1) (5) (8). There are usually up to 3 offspring per litter, and the young are relatively well developed at birth, weighing about 4 grams and opening their eyes at 10 to 11 days old (3) (8). The young San Joaquin kangaroo rats first leave the burrow at about 14 to 18 days old and are weaned at 21 to 24 days, attaining adult weight after about 2.5 to 3 months (3). The San Joaquin kangaroo rat reaches sexual maturity as early as 82 days old (5), and females may potentially give birth to up to three litters a year (1).
The San Joaquin kangaroo rat is predated by a range of mammals, birds and reptiles, including bobcats (Lynx rufus), coyotes (Canis latrans), long-tailed weasels (Mustela frenata), barn owls (Tyto alba), hawks and snakes (3) (5).