Chaetodipus fallax was known as Perognathus fallax until 1983 when the genus Chaetodipus was used to classify all spiny pocket mice.
Due to their solitary nature, very little is known about communication between San Diego pocket mice. When in danger, they have been observed to squeak, suggesting that some form of vocal communication may be used. They use their large ears and eyes, as well as their good sense of touch, to perceive their environment.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
San Diego pocket mice are common in their habitat, and seem to be under no immediate threat. However, due to the expansion of human cities, like San Diego, there is a decrease in possible habitat. The severity of this is not well known but does not appear to suggest any immediate threat for C. fallax.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of Chaetodipus fallax on humans.
There are no known positive effects of Chaetodipus fallax on humans.
In addition to providing food for a number of predators and eating many kinds of plants, San Diego pocket mice play several roles in their ecosystem. Through burrowing, they help to aerate the soil. The manner in which they store their seeds helps the plants distribute their offspring. They are also the host for a number of mites and fleas. In addition, they live in constant competition with other small rodents found in the same region. In order to reduce competition over food, Chaetodipus fallax rely more on seeds with high amounts of moisture, leaving the drier seeds for rodents that obtain more of their needed water through drinking. The competition between species is also seen in habitat use. San Diego pocket mice typically inhabit the rockier microhabitats in the region, while other soil types contain other rodents. As changes in the microhabitats occur, however, so too does the community of the rodent inhabitants. An example of this has been seen in regions that have increased plant density, providing more protection for C. fallax. As populations of Chaetodipus fallax have increased in these regions, Dipodomys merriami, a competing species, have decreased.
Ecosystem Impact: disperses seeds; soil aeration
Commensal/Parasitic Species:
San Diego pocket mice are predominantly granivores, eating the seeds from a variety of shrubs and grasses found in their habitat. Their cheeks have fur-lined pouches in which they can store these seeds to carry them back to their burrows where they are stored. These pouches help keep the seeds isolated from the moisture of the mouth, helping C. fallax to avoid losing water to the seeds. In fact, they are so good at conserving water that they can survive on just seeds alone, getting all necessary water from either food or the byproducts of metabolic processes. As ambient temperature increases, San Diego pocket mice tend to more exclusively eat seeds that contain high amounts or moisture to compensate for the additional losses of moisture due to the heat. In times of seed shortage, San Diego pocket mice may also eat leaves, stems, and even insects.
Animal Foods: insects
Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore )
Chaetodipus fallax are a Nearctic species, inhabiting a region in southwestern California surrounding San Diego and extending south into northwestern Baja California, Mexico.
Biogeographic Regions: nearctic (Native )
San Diego pocket mice are found terrestrially in a wide variety of temperate habitats ranging from chaparral and grasslands to scrub forests and deserts. This area includes a vast range of elevations, extending from sea level along the Pacific coast to around 1400 m in the mountains of southwest California and Baja California. Rarely found in cities, the major habitat requirement for C. fallax is the presence of low growing vegetation or rocky outcroppings, as well as sandy soil in which they dig burrows.
Range elevation: 0 to 1400 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; scrub forest
The lifespan of C. fallax ranges from about 4 months to nearly 2 years in the wild. Mortallity is largely due to predation, which occurs most heavily during the spring months. At this time, San Diego pocket mice are most active foraging, reproducing and defending their territories. In captivity, without the presence of predators, C. fallax can live up to 6 years.
Typical lifespan
Status: wild: 4 to 18 months.
Average lifespan
Status: wild: 5 months.
Typical lifespan
Status: captivity: 5 to 6 years.
San Diego pocket mice are moderately sized pocket mice, ranging in length from 170 to 200 mm and weighing from 17 to 22 grams. There is very little difference in size between males and females. Both are colored a dark brown on top and white underneath, with spines that are black on the rump and white on the hips. The tail length is shorter than the body by about 20 mm, it has a darkly colored dorsal crest and is and light below. This appearance is very similar to Chaetodipus californicus that also occupy the same general habitat except that C. fallax has shorter ears, usually shorter than 9 mm. San Diego pocket mice are homeothermic endotherms with hypsodont and lophodont teeth.
Range mass: 17 to 22 g.
Average mass: 20 g.
Range length: 170 to 200 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 0.15 W.
Chaetodipus fallax are preyed on by a variety of foxes, coyotes, badgers, owls, and snakes. In order to avoid predation, they have dark pelage to help camouflage at night, when they are most active. They also have an erratic hopping style when being pursued by a predator, making it difficult to anticipate their path. The burrows in which they live also provide some safety from these predators, and the young remain in the shelter of the burrows until they are able to survive on their own.
Known Predators:
Anti-predator Adaptations: cryptic
Due to the solitary nature of C. fallax not much is known about their mating habits. In addition, they rarely breed in captivity, making analysis of their habits even more difficult. San Diego pocket mice are known to mate throughout the year, however mating appears to be concentrated during the spring.
San Diego pocket mice typically reproduce once a year in the spring, however, some have been known to reproduce year round and as much as three times a year. It appears that reproductive patterns are strongly related to rainfall. Each litter typically contains between 2 to 6 young that mature in 5 to 6 months. The gestation period for C. fallax is about 24 to 26 days. Not many details are known about the rearing patterns of San Diego pocket mice.
Breeding interval: San Diego pocket mice can produce 1 to 3 litters per year.
Breeding season: Most San Diego pocket mice breed in the spring but they do breed year round in the right conditions
Range number of offspring: 2 to 6.
Range gestation period: 24 to 26 days.
Range age at sexual or reproductive maturity (female): 5 to 6 months.
Range age at sexual or reproductive maturity (male): 5 to 6 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Average number of offspring: 3.
There is very limited information related to the parental investment of San Diego pocket mice. Females are the exclusive caregivers, birthing, nursing, and protecting their young inside their burrows. The specifics pertaining to the types of care given and the duration of this care are not known.
Parental Investment: precocial ; female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The San Diego pocket mouse (Chaetodipus fallax) is a rodent species in the family Heteromyidae.[2] It occupies the northern region of Baja California near San Diego extending into Mexico.
The San Diego pocket mouse occupies the northern region of Baja California near San Diego extending into Mexico. This moderately sized mouse is characterized by dark brown fur covering the top of its body with white fur on its underside. Its length ranges from 170 to 200 mm and its weight is approximately 17–22 g. The San Diego pocket mouse is a homoeothermic endotherm with both hypsodont and lophodont teeth. Similar species include C. californicus, which shares the same habitat.
The San Diego pocket mouse is often a solitary animal, which makes it difficult to study its reproductive history. Many individuals mate in the spring, but others have been known to mate throughout the year. Reproduction occurs 1–3 times a year. There is significant evidence that correlates reproductive events with rainfall. An average litter is composed of 2–6 individuals with an average gestation period of 24–26 days. Females serve as the primary caregivers for their offspring, nursing young and protecting them inside their burrows.
San Diego pocket mice have a lifespan ranging from four months to two years in the wild. Mortalities often result from predation, which increases in the spring when mice are actively foraging, reproducing and defending territories. In captive studies without predation, individuals have been known to live up to six years.
The San Diego pocket mouse is built for slow quadrupedal locomotion. At higher speeds, the pocket mouse “gallops” by hitting the ground with both feet and using its tail for balance. The mice forage at night in attempt to avoid predators. Food is gathered in cheek pouches and stored in separate burrow chambers. Burrows serve as the primary habitat for the mouse in the winter during a period of decreased activity. Burrows are divided into separate chambers with one for sleeping and the rest for storing food. Verbal communication may be utilized to indicate the presence of danger in some cases when a mouse squeaks. Large eyes and ears help individuals sense their surroundings.
Males often occupy a home range of 3,500 square metres (38,000 sq ft) while females occupy a range of 2,500 square metres (27,000 sq ft). Territories are often defended to protect habitat from intruders with the exception of potential mates during the breeding season. A typical home range is composed of rocks, sand and herbaceous vegetation for cover. Some common plants seen in these habitats include Yucca and desert scrub.
San Diego pocket mice are granivores and predominantly forage on seeds. Their cheeks have fur-lined pouches for storing seeds. These mice can subsist on seeds alone and are capable of surviving without drinking additional water. In this case, San Diego pocket mice are able to obtain their water through food or metabolic by-products. In high temperatures, San Diego pocket mice consume seeds with high moisture to compensate for evaporative cooling and water loss during warmer weather. If seeds are in short supply, individuals have been known to eat leaves, stems and insects to replace their normal diet.
The San Diego pocket mouse is subject to predation by a variety of predators, including: foxes, coyotes, badgers, owls and snakes. To avoid predation, mice are characterized by a dark pelage that keeps them camouflaged while they are active at night. A varied hopping style deployed by the mice also makes it difficult for predators to catch the mice.
The San Diego pocket mouse has a significant impact on the ecosystem in its ability to aerate the soil through burrowing. The method in which the mice forage for seeds and store them in their cheek pouches is beneficial for seed dispersal in plants. San Diego pocket mice are also host to a number of ticks and fleas. They are also subject to competition with other rodents that share the same niche. Some rodents are able to coexist as rodents that require more moisture consume higher moisture seeds and leave drier seeds for rodents that require more moisture through drinking.
On the ICUN Red List, the San Diego pocket mouse is classified as a species of least concern. The San Diego pocket mouse is under no immediate threat.
The San Diego pocket mouse (Chaetodipus fallax) is a rodent species in the family Heteromyidae. It occupies the northern region of Baja California near San Diego extending into Mexico.
