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Liomys salviniSalvin's spiny pocket mouse

By Elisabeth Witt

Geographic Range

Liomys salvini is found along the Pacific slope in the southern Mexican states of Oaxaca and Chiapas south through Central Costa Rica. From the Pacific Slope, the range extends significantly inland in Southern Guatemala, Southern Honduras, and Nicaragua. It is usually found from the lowlands to elevations of 1500 meters.

(Reid, 1997)

Habitat

Typically Liomys salvini are found in drier habitats than other tropical pocket mice (especially Heteromys desmarestianus, which live in wet tropical forests). They are found in dry tropical forests and in brushy, weedy fields. L. salvini are most often trapped along walls or rocks.

(Flemming, 1975, Reid, 1997)

Physical Description

Head and body length: 103-140 mm

Tail length: 97-144 mm

Hind foot length: 26-30 mm

Ear length: 12-16 mm

Liomys salvini is sexually dimorphic, with females averaging 39g and males averaging 51g. When males are sexually active their scrotal testes are greatly enlarged.

Liomys salvini is a small to medium sized rodent. Like other pocket mice, L. salvini has external, fur-lined pouches in its cheeks for carrying seeds and other materials. Although the darkness of the fur can vary quite a bit geographically, L. salvini is always grey or grey-brown dorsally with cream-colored underparts, forelegs, and feet. The darker dorsal fur is interspersed with dark spiny hairs and lighter, cream-colored hairs. The tail is approximately equal to the body length, bicolor, and nearly hairless (although it may have a short terminal hair tuft). In regions of overlap, L. salvini can be distinguished from other species by the lack of orange side stripes (/Liomys pictus/) and a lack of dark forelimbs (/Heteromys desmarestianus/). Body and tail proportions are also different between species.

(Reid, 1997, Flemming, 1983)

  • Range mass
    30 to 65 g
    1.06 to 2.29 oz

Reproduction

The reproductive season stretches from January in the dry season to about mid-June in the early wet season. Average litter size is 3.8 young. Females have one to two litters annually, and may have a litter late in the breeding season in which they were born. Males mature sexually at approximately 6 months. Life span is relatively short, resulting in a high turnover rate in the population and dominance by last year's young. Most individuals will survive for only one year and a few individuals will live to be 15 to 18 months old. Females nest within individual burrow systems.

(Flemming, 1983, Reid, 1997)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

Liomys salvini are nocturnal, quadrupedal, and poor tree climbers. They are most often observed at night on forest floors or in weedy fields.

Liomys salvini is less social than other species of pocket mice. In dry forest systems, home ranges of .20 ha overlap but intolerance and aggression is shown to members of the same sex. This results in the clumping of female home ranges around male home ranges. Larger individuals are dominant over smaller individuals and adults are dominant over the young of the year. Aggression does not vary according to season.

Liomys salvini individuals are intense seed hoarders and burrowers. Within each home range, an individual may construct several large burrow systems with several entrances. The seeds they collect are cached within their burrows and in shallowly-constructed pits around their home range.

Liomys salvini have been shown to enhance their diet through modification of cached seeds. Very hard and dry seeds do not make up a healthful diet but L. salvini individuals often collect and store these seeds through the dry season. Before storing, an L. salvini individual notches the seed coat with its incisors. Seeds with notches soften during the wet season and germinate into higher-quality food.

Experiments (Flemming 1977) have been conducted to test L. salvini's ability to withstand food and water deprivation. Perhaps as a result of adaptation to its normal habitat (dry forests), L. salvini was more able to withstand water deprivation than other tropical pocket mice. Water deprivation resulted in 3.4% daily body mass loss, and individuals survived at least one week without water. Food deprivation is also tolerated; individuals were able to lose 20% of their total body weight without any significant signs of weakness.

(Flemming, 1974, Flemming, 1977, Flemming, 1983, Reid, 1997)

Communication and Perception

Food Habits

Although Liomys salvini eat some insects, they are mainly a seed-eaters. In Costa Rica, L. salvini favors the seeds of the buttercup tree (/Cochlospermum vitifolium/) during the dry season. During other seasons they eat the seeds of many other species, including the poisonous seeds of guanacaste (/Enterolobium cyclocarpum/). Seeds are located by odor and they can reportedly locate seeds that are buried in dung.

(Flemming, 1983, Flemming, 1975, Reid, 1997)

Economic Importance for Humans: Positive

Liomys salvini may be important in supporting diverse faunas, dispersing tropical forest seeds, and in insect control.

(Flemming, 1983)

Economic Importance for Humans: Negative

No negative impacts have been reported.

Conservation Status

Liomys salvini has no special conservation status, but is presumably negatively impacted by deforestation and habitat destruction. In dry forested areas it is still locally common.

Reid (1997)

Other Comments

T. H. Flemming calls Liomys salvini a "key industry" animal of the tropical forests. Because it is so abundant, the pocket mouse is an important food source for diverse groups of carnivorous animals including birds, snakes, and small cats. Because it is an avid seed hoarder, L. salvini is also an important disperser of seeds. L. salvini may also make a contribution to the control of insect larvae, although no study has suggested that this benefits human farming or forestry systems.

(Flemming, 1983)

Contributors

Elisabeth Witt (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, 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

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

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.

forest

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

motile

having the capacity to move from one place to another.

native range

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

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

tactile

uses touch to communicate

References

Flemming, T. 1974. Social organization in two species of Costa Rican Heteromyid rodents. Journal of Mammalogy, 55: 543-561.

Flemming, T. 1974. The population ecology of two species of Costa Rican heteromyid rodents. Ecology, 55: 493-510.

Flemming, T. 1983. Liomys salvini (Raton Semiespinosa, Guardafiesta, Spiny Pocket Mouse). Pp. 475-477 in D Janzen, ed. Costa Rican Natural History. Chicago: University of Chicago Press.

Flemming, T., G. Brown. 1975. An experimental analysis of seed hoarding and burrowing behavior in two species of Costa Rican Heteromyid rodents. Journal of Mammalogy, 56: 301-315.

Reid, F. 1997. A Field Guide to the Mammals of Central America and Southeast Mexico. New York: Oxford University Press.

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