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Liomys pictuspainted spiny pocket mouse

By Lindee Mason

Geographic Range

Painted spiny pocket mice (Liomys pictus) are native to Central America. They are found along the coasts, in the Sonoran Desert, and within the mountains of Mexico. They are also found in western Guatemala and throughout the Isthmus of Tehuantepec (a small piece of land that connects Mexico and Guatemala). (McGhee and Genoways, 1978)

Habitat

Painted spiny pocket mice are found in different habitats throughout Mexico. They live in forests of coastal lowlands in the east, in forests and grasslands of the Sierra Madre Occidental, and in humid montane forests of the Sierra Madre del Sur mountain ranges. Painted spiny pocket mice have been found at elevations ranging from 0 to 7,300 m. They are also found within cloud forests of the Guerrero and Oaxaca mountains. They also live in the Sonoran Desert, in northwestern Mexico. However, painted spiny pocket mice are most commonly observed in areas that are populated with cacti and/or acacia trees, or along streams that are located in arid environments.

Painted spiny pocket mice make their nests out of leaves. They create burrows underneath logs, rocks, and shrubs for shelter and food storage. These burrows consist of tunnels and chambers, where they build nests, store food, and deposit waste. These burrows can be simple set-ups containing just one tunnel, or very complex networks of numerous tunnels (1 to 23 chambers and up to 3 nests). Their burrows are usually 18 to 75 cm in depth. (Ceballos, 2014; McGhee and Genoways, 1978; Reid and Vázquez, 2016)

  • Range elevation
    0 to 7300 m
    0.00 to 23950.13 ft

Physical Description

Painted spiny pocket mice have white ventral sides and reddish-brown dorsal sides with a single lateral stripe that is either ochre or pale in color. Their coats are made up of a mixture of stiff spines and soft, fine hair. The fine hairs do not grow longer than the spines, meaning the spines stick out.

Painted spiny pocket mice are medium in size, with total body lengths ranging from 212 to 264 mm and masses ranging from 30 to 80 g. Juveniles are grey in color and lack spines within their pelage. When compared to adult females, adult males are larger on average in total length, tail length, hindfoot length, skull length, mastoid breath, and interorbital constriction size. Males are also larger on average with regards to zygomatic width, nasal length, braincase depth, and interparietal width. Average maxillary toothrow lengths and interparietal lengths are the same for both males and females. Male painted spiny pocket mice have the longest bacula compared to other species in the genus Liomys.

The dental formula for painted spiny pocket mice is 1/1, 0/0, 1/1, 3/3, totaling 20 teeth. The formula is not unique to this species - it is the same as all the other species in the family Heteromyidae. On the plantar side of their hindfeet they have six tubercles, along with hair on their soles. Their pterygoid bones extend ventrally and then turn laterally. The shape of their pterygoid bone helps differentiate their skulls from sympatric species in the genus Liomys.

Painted spiny pocket mice molt once annually, but they only molt their dorsal fur. Molting begins simultaneously in two different areas. The first area is 1/3 of the way between the ears. Molting moves posteriorly down to their rumps and expands laterally. The second location of molting is the fur on the top of the head. Molting is finished once all the fur on the rump has been replaced. Molting usually occurs between April and June, but it is not uncommon for individuals to molt in February, March, or November.

Painted spiny pocket mice have four different subspecies: L. pictus annectens, L. pictus hispidus, L. pictus pictus, and L. pictus plantinarensis. Liomys pictus annectens is the largest of the subspecies. They can be differentiated from other subspecies by their large bodies and crania. They also have a darker dorsal coloration. Liomys pictus hispidus intermediate in size. They can be differentiated from the other subspecies by their relatively short interparietal bones, which are also notched posteriorly. Their premaxillary and nasal bones also terminate at the same level. Liomys pictus pictus are moderate to large in size. They have broad interparietal bones and their premaxillary bones terminate posteriorally to their nasal bones. Liomys pictus plantinarensis are the smallest of the four subspecies and they have characteristics that closely resemble those of Liomys pictus pictus. One of the only differences is that they have five tubercles on the plantar sides of their hindfeet instead of six. (Ceballos, 2014; McGhee and Genoways, 1978)

  • Sexual Dimorphism
  • male larger
  • Range mass
    30 to 80 g
    1.06 to 2.82 oz
  • Range length
    212 to 264 mm
    8.35 to 10.39 in

Reproduction

When a male painted spiny pocket mouse comes in contact with a female, they will sniff each other’s noses. The male will then drive, groom, pat, or mount the female. The male will also investigate the female’s perineum. The female being courted will arch her back when mating takes place. The male only stays with the female up until parturition, then leaves in pursuit of another mate. Because males mate with multiple females in one breeding season, painted spiny pocket mice are considered polygynous. (McGhee and Genoways, 1978)

Painted spiny pocket mice are able to breed all year round, but tend to do so less in the early months of the dry season. This decrease in reproduction during the dry season could be due to lack of resources; their hoarded food could be running low. Since they live off of hoarded food during the wet season they have no time to collect food when the dry season first begins. Females tend to have two to six embryos, but common litter sizes range from two to five pups. Male mice have enlarged testes during most of the year except for November to February. Gestation usually lasts between 24 to 26 days. Young painted spiny pocket mice leave the nests of their parents within one to two months after birth, often due to sibling aggression. (McGhee and Genoways, 1978; Reid and Vázquez, 2016)

  • Breeding interval
    Painted spiny pocket mice breed every 24 to 26 days
  • Breeding season
    Painted spiny pocket mice breed year-round
  • Range number of offspring
    2 to 6
  • Range gestation period
    24 to 26 days
  • Range time to independence
    1 to 2 months

Since male painted spiny pocket mice leave at the time of birth, females are responsible for all parental care. Females give birth to altricial young, so a fair amount of parental care is needed.

Female mice are prone to bolt from their nests if the nests are disturbed. Once they feel like it is safe to return, they will come back to move their nest and young. They move their young by putting their babies in their cheek pouches. This movement causes prolonged development of offspring. (McGhee and Genoways, 1978)

Lifespan/Longevity

There is little information regarding the lifespan of painted spiny pocket mice. However, most closely-related mouse species tend to live 1 to 2 years in the wild, with 4 to 5 years being the longest recorded lifespan. (Gorbunova, et al., 2008)

Behavior

Painted spiny pocket mice are aggressive, solitary animals that are only social for mating purposes. They are a nocturnal species and can often be found sandbathing, caching seeds, and scratching or washing their bodies. Since they are a nocturnal species, painted spiny pocket mice mostly stay within their burrows until nightfall.

Painted spiny pocket mice are commonly observed dragging their perinea to mark objects with their scent. They may also bristle their hair (a behavior known as piloerection) to help with thermoregulation or as a warning to other mice. They may also exhibit trembling of the tail as a warning sign to other mice. Tail trembling usually marks the beginning of a fight with another mouse. Aggressive behavior between mice includes rushing, locked fighting, and chasing. During a locked fight, both participants take upright positions. They lock arms and fight by using their hind legs or their teeth. Fights can last as long as a minute. These mice fight to defend their territories, protect mates, and possibly even protect resources if they are scarce.

There is little information regarding the territories of painted spiny pocket mice, but mice in general are known to be territorial. A study done on house mice (Mus musculus) found that male mice tended to keep territories that house 1 to 2 females. Most mice species are solitary, so painted spiny pocket mice may behave similarly.

In one study, the density of individuals in certain areas were analyzed. In lowland forests 2 to 71 individuals were found per hectare of land and in open forests 2 to 49 individuals were found per hectare of land. How densely populated an area is can provide information on how a species disperses. If a species is highly territorial, then there will be fewer individuals within a given area. At their highest densities - 71 per hectare for lowland forests and 49 per hectare for open forests. With this information it can be inferred that mice have territories approximately 141 m wide in lowland forests and approximately 205 m wide in open forests.

Painted spiny pocket mice are saltatorial, meaning they move around by hopping. They can walk normally, with a diagonal limb coordination and quadrupedal ricochets. Painted spiny pocket mice are able to climb, but their bodies are not specialized to do so. (Ceballos, 2014; Crowcroft, 1955; McGhee and Genoways, 1978)

Home Range

No information was found regarding the home range for painted spiny pocket mice.

Communication and Perception

Painted spiny pocket mice are able to communicate acoustically by tooth-chattering, growling, squealing, grunting, and twittering. Since they are typically solitary, painted spiny pocket mice do not communicate with each other often, but they will socialize to find and secure mates.

When a female and male mouse meet, they greet one another nose to nose, but when same gender mice meet, they greet one another nose to anus. They have also been observed putting their heads over the other mouse or crawling under each other. (McGhee and Genoways, 1978)

Food Habits

Painted spiny pocket mice are considered specialized granivores. This branch of herbivory means that they mainly eat seeds. Mice in the family Heteromyidae are adapted to live in arid environments where food availability is often unpredictable. Since they do not migrate or change eating habits during different seasons, they have to rely on food that they have hoarded. Painted spiny pocket mice hoard many different plant materials inside their burrows during the dry season, when food is more abundant. They live off this hoarded food when food becomes limited.

Seeds make up the majority of the diet of painted spiny pocket mice. However, they are also known to eat green vegetation and various arthropods like spiders, beetles, crickets, and moths, mostly during the rainy season. In areas where C3 (most plants) and C4 (cacti) plants are both found, painted spiny pocket mice tend to show no preference between the two types. These mice also do not need to drink water, so long as their diets contains enough water-rich foods. (Ceballos, 2014; McGhee and Genoways, 1978; Ramirez-Hernandez and Herrera-Montalvo, 2010; Reid and Vázquez, 2016)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

No specific information was found regarding the predators of painted spiny pocket mice, but there is information on known predators of closely-related Salvin’s pocket mice (Liomys salvini). Predators include snakes, cats, owls, skunks, possums, coyotes, and gray foxes. Since these two species of mice share the same geographic ranges and prefer the same type of habitat, they most likely share similar predators. (Carter and Genoways, 1978)

Ecosystem Roles

Due to their primary diet of seeds, painted spiny pocket mice are able to positively impact their environment by maintaining the structure of vegetation and caching seeds. Additionally, due to their tendency to cache seeds and then lose some, they likely contribute to seed dispersal. (Ceballos, 2014)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

There is no evidence suggesting that painted spiny pocket mice have a positive economic value for humans.

Economic Importance for Humans: Negative

There are no known adverse effects of painted spiny pocket mice on humans.

Conservation Status

According to the IUCN Red List, painted spiny pocket mice are of least concern, but increased logging and wood harvesting is a threat to this species. Currently, land and water protection policies are in place to help decrease the threats to this species. (Reid and Vázquez, 2016)

Other Comments

"Pictus" is derived from the Latin word meaning painted (pict-). "Annectens" is derived from the Latin word meaning to bind together (annect-). "Hispidus" is derived from the Latin word meaning hairy or bristly (hispid-). "Plantinarensis" is derived from the name of a town where a specimen of this species was found. This town was called Platanar, but it was misspelled as Plantinar on the specimen label, creating the species’ name.

Painted spiny pocket mice may also be referred to by the outdated Latin name Heteromys pictus. (McGhee and Genoways, 1978; Reid and Vázquez, 2016)

Contributors

Lindee Mason (author), Purdue University - Fort Wayne, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Carter, C., H. Genoways. 1978. Liomys salvini. Mammalian Species, 88: 1-5.

Ceballos, G. 2014. Mammals of Mexico. Baltimore, Maryland: Johns Hopkins University Press.

Crowcroft, P. 1955. Territoriality in Wild House Mice, Mus musculus L.. Journal of Mammalogy, 36/2: 299-301.

Gorbunova, V., M. Bozzella, A. Seluanov. 2008. Rodents for Comparative Aging Studies: From Mice to Beavers. Age (Dordrecht, Netherlands), 30/2-3: 111-119.

McGhee, M., H. Genoways. 1978. Liomys pictus. Mammalian Species, 87: 1-5.

Ramirez-Hernandez, G., L. Herrera-Montalvo. 2010. Nutritional Importance of Seeds and Arthropods to Painted Spiny Pocket Mice (Liomys pictus): the effects of Season and Forest Degradation. Canadian Journal of Zoology, 88: 1226-1234.

Reid, F., E. Vázquez. 2016. "Heteromys pictus" (On-line). The IUCN Red List of Threatened Species.

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