Thallomys paedulcus

Geographic Range

Acacia rats are found in sub-Saharan Africa. They occur widely from the southern-most portion of Ethiopia, south to the east coast of South Africa. Their range extends to the west coast of Angola, through Zambia, Malawi and Zimbabwe.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Thallomys paedulcus lives under the frayed bark of acacia tree trunks and branches, primarily Acacia xanthophloa and Acacia tortilis . It can sometimes seen near river beds. Its nests, which have been seen as high as 4 m from the ground, become highly visible during winter when foliage decreases. Acacia thorns provide optimal protection against predators.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

Physical Description

Acacia rats have a white venter and a grey-yellow dorsum. The fur is dense and soft and their ears are sparsely covered in hair. They have elongate hind- and forepaws, which possess long, curved claws. THeir brown tail is used to distinguish them from black-tailed tree rats . In addition, black-tailed tree rats have a more complete eye mask than acacia rats. Although they were once considered the same species, recent chromosomal evidence suggest they are distinct species. Acacia rats weigh between 63 and 100 g, with an average of 68 g. Weight can vary substantially in females, with weight increasing during lactation. Body length ranges from 12 to 16.3 cm, and the tail is often greater than or equal to the body, ranging from 13 to 21 cm. Sexual dimorphism has not been reported for this species.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

There is little information on the mating system of Acacia rats. They give birth during the summer rainy season, when acacia foliage is present. Similar to many other murids , acacia rats are polygynandrous. Males expand their home ranges during breeding season, presumably in order to increase the likelihood of finding potential mates.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

There is little information available regarding the reproductive behavior of acacia rats, and that which is know was discovered via lab studies. They normally breeds every 3.5 months during summer (April through July) and litters consists of 2 to 5 pups, which weigh between 2.5 to 2.8 g t birth. Young are weaned 28 and 31 days old and reach sexual maturity at an average of 107 days. Pups begin walking after 15 days and incisors appear only after one day. Reproduction in acacia rats is thought to be similar to that of black-tailed tree rats .

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

There is no information available regarding parental care in wild acacia rats. In captivity, young attach to the nipple and nurse while the mother moves around the local environment. Pups stay with their parents until they reach reproductive maturity.

• Parental Investment
• female parental care female parental care
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

THe average lifespan of wild acacia rats has not been documented. Captive individuals live for an average of 3 years.

Behavior

Little is known of the general behavior of acacia rats. They are arboreal and nocturnal, with nightly activities beginning prior to dusk. They construct nests out of leaves, grass, and small twigs. They burrow along Acacia tree root structures and use these burrows in the winter months in the event of brush fires.

• Key Behaviors
• arboreal arboreal
• nocturnal nocturnal
• motile motile
• social social

Home Range

Home range size varies in relation to sex. Female home ranges are about 10,000 m^2. Male home ranges are about 100,000 m^2 and sometimes overlapping into the range of another male. Males expand their home range during breeding season, likely increasing their chances of finding potential mates.

Communication and Perception

Little is known about communication and perception of acacia rats. They appear to be very shy and rarely leave their shelters. They primarily live in conspecific communities and use scent markings to demarcate territorial boundaries.

• Communication Channels
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Acacia rats are primarily granivorous, feeding on the seeds and foliage of acacia trees . They have been observed foraging on Acacia tortilis and Acacia erioloba . The leaves of shepherd’s trees and seeds of buffalo thorn are also considered an important part of their diet. Other primarily granivorous, they also consume the berries, grasses, roots, buds, and gum of acacias . Food is generally brought back to the nest preior to consumption. Inedible plant materials are often used in nest making. They may also consume carrion or invertebrates when available.

• Primary Diet
• herbivore herbivore
  • granivore granivore
• omnivore omnivore

• Animal Foods
• carrion carrion
• insects
• terrestrial non-insect arthropods

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts
• sap or other plant fluids

• Foraging Behavior
• stores or caches food stores or caches food

Predation

Acacia rats inhabit the thickest and thorniest parts of Acacia trees, which is an extremely effective in predator avoidance. Their sandy pelage provides great camouflage and likely helps reduce predation risk. It is thought that owls are their primary predators, however, arboreal snakes (e.g., Dendroaspis spp.) are important predators as well.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Thallomys paedulcus is prey for a number of vertebrate predators including owls and a variety of snakes . As an arboreal rodent , it fills a unique niche that is not exploited by many rodents. Parasites of this species include the flea species Xemonpsylla brasiliensis , a known vector of the plague ( Yersinia pestis ), and Echidnophaga gallinacea .

Economic Importance for Humans: Positive

Although Thallomys paedulcus is not often seen in the pet trade, they are occasionally sought for their attractive coloring. Compared to other rodents, they breed poorly in captivity, making them unsuitable for lab use.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

Acacia rats are possible vectors for the plague ( Yersinia pestes ). There are no other known adverse effects of acacia rats on humans.

• Negative Impacts
• injures humans
  • carries human disease

Conservation Status

Acacia rats are classified as a species of least concern on the IUCN's Red List of Threatened Species List. Although current population trends are unknown, they are thought to be widespread and locally abundant throughout their geographic range. Currently, there are no major threats to the long-term persistence of this species.

Additional Links

Encyclopedia of Life

Contributors

Casey Ford (author), Northern Michigan University, Mary Martin (editor), Northern Michigan University, John Berini (editor), Animal Diversity Web Staff.

References

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Eccard, J., J. Meyer, J. Sundell. 2004. Space Use, Circadian Activity Pattern, and Mating System of the Nocturnal Tree Rat Thallomys nigricauda. Journal of Mammalogy , 85/3: 240-245.

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2. Notes on Early Postnatal Development in Certain Southern African Muridae and Cricetidae

Meyer, J., A. Kohnen, R. Brandl. 2010. Genetic differentiation in an arboreal rodent from African savannas. African Journal of Ecology , 41/3: 831-836.

Meyer, J., D. Raudnitschka, J. Steinhauser, F. Jeltsch, R. Brandl. 2008. Biology and ecology of Thallomys nigricauda (Rodentia, Muridae) in the Thornveld savannah of South Africa.. Mammalian Biology , 73/2: 111.

Mills, M., L. Hes. 1997. The complete book of southern African mammals . Cape Town, South Africa: Struik Book Distributors.

Skinner, J., C. Chimimba. 2005. The Mammals of South Africa Subregion . Cambridge, UK: Cambridge University Press.

Welton, N. 2004. Rats, Mice, and Relatives III: Old World Rats and Mice (Murinae). Pp. 249-262 in Grzimek's Animal Life Encyclopedia , Vol. 16, 2nd Edition. Detroit: Gale Virtual Reference Library. Accessed March 10, 2011 at http://ezpolson.nmu.edu:5749/ps/start.do?p=GVRL&u=lom_nmichu .

de Graaff, G. 1978. Notes on the Southern African black-tailed tree rat thallomys paedulcus (Sundevall, 1846) and its occurrence in the Kalahari Gemsbok National Park. Koedoe , 21/1: 181-190.