Tlacuatzin canescensgray mouse opossum(Also: grayish mouse opossum)

Geographic Range

Tlacuatzin canescens is found in the neotropical region. Grayish mouse opossums are endemic to Mexico (Zarza, Ceballos and Steele, 2003). They are found along the western and southern coasts of Mexico, from the Baja peninsula to the Yucatan peninsula (Nowak, 1991; Zarza, Ceballos and Steele, 2003). Isolated populations occur on the Tres Marias Islands off of the Nayarit coast (Zarza, Ceballos and Steele, 2003). Some evidence suggests that this species also occurs in Guatemala; however it has not yet been confirmed there (Voss and Jansa, 2003). (Nowak, 1991; Sanchez-Cordero, et al., 2005; Voss and Jansa, 2003; Zarza, et al., 2003)


Grayish mouse opossums generally live in semi-deciduous and tropical forests that exhibit distinct wet and dry seasons (Zarza, Ceballos and Steele, 2003). However, they are also found in other habitats, including scrublands, grasslands, evergreen forests, orchards, fields and secondary-growth forests (Zarza, Ceballos and Steele, 2003). Tlacuatzin canescens is most often found at elevations below 1,000 m; but have been observed up to 2,100 m (Zarza, Ceballos and Steele, 2003). (Nowak, 1991; Zarza, et al., 2003)

Grayish mouse opossums live in nests near logs, rocks, tree hollows, cacti, and shrubs (Zarza, Ceballos and Steele, 2003). One study found that nearly all specimens of T. canescens in Sinaloa, Mexico lived in hollow areas of dead cacti (Nowak, 1991). Nests are typically made up of dry leaves, small stems and the plant fibers of Ceiba pentandra. Additionally, some individuals have been found living in the abandoned nests of birds, including Uropsila leucogastra and Thryothorus pleurostictus (Zarza, Ceballos and Steele, 2003). (Nowak, 1991; Zarza, et al., 2003)

  • Range elevation
    0 to 2100 m
    0.00 to 6889.76 ft
  • Average elevation
    1000 m
    3280.84 ft

Physical Description

Tlacuatzin canescens individuals exhibit considerable variation. In particular, the population found in the Yucatan peninsula is distinct from populations in western Mexico (Voss and Jansa, 2003). (Voss and Jansa, 2003)

In general, this species has brownish to light gray fur on its upper parts and creamy to white fur on its legs (Zarza, Ceballos and Steele, 2003). The venter is yellow-cream in color. Eyes are surrounded by black rings, and the ears are rounded, broad, and lack hair. The fur varies from soft and short to coarse and long (Zarza, Ceballos and Steele, 2003. The tail is prehensile and partly covered in fur (sometimes with a white tip). The tail is about the same length as the body. The hind feet are naked from the toes to the heel and the fourth digit is longer than the others. In mature females, an orange-yellow patch of fur surrounds the inguinal mammae (Zarza, Ceballos and Steele, 2003). Except for this feature, males and females look almost identical. Tlacuatzin canescens is very small, the smallest opossum found in Mexico (Zarza, Ceballos and Steele, 2003). (Zarza, et al., 2003)

The skulls of T. canescens have strongly developed zygomatic arches and post-orbital processes, and the skull is broad and short (Zarza, Ceballos and Steele, 2003). The dental formula is 5/4, 1/1, 3/3 and 4/4 (Eisenberg, 1989). (Eisenberg, 1989; Zarza, et al., 2003)

  • Sexual Dimorphism
  • sexes alike
  • sexes colored or patterned differently
  • Range length
    205 to 350 mm
    8.07 to 13.78 in


Grayish mouse opossums are solitary mammals and reproduction is promiscuous. Males attract females by emitting clicking sounds (Eisenberg, 1989). During copulation, the male and the female suspend themselves upside down with the use of their prehensile tails (Zarza, Ceballos and Steele, 2003). Throughout copulation, the male grasps the female's neck with his mouth (Zarza, Ceballos and Steele, 2003). Once copulation is over, the male is rejected by the female and both leave the area (Zarza, Ceballos and Steele, 2003). (Eisenberg, 1989; Zarza, et al., 2003)

Tlacuatzin canescens reproduces year round (Ceballos, 1990). However, females are most often found with young from July to September (Zarza, Ceballos and Steele, 2003). Litter size ranges from 8 to 14 and the average number of young is 11 (Zarza, Ceballos and Steele, 2003). Juveniles leave their mothers once they reach a mass of around 20 grams. Unlike many other marsupials, T. canescens females do not possess a pouch. Instead, they have a layer of hair found on their ventral side in which newborns finish developing (Zarza, Ceballos and Steele, 2003). (Ceballos, 1990; Zarza, et al., 2003)

There is little information regarding gestation for T. canescens. In M. robinsoni, a closely related species, gestation is typically 14 days. Females of this species reach sexual maturity when they are approximately 6 months old. (Nowak, 1991)

  • Breeding interval
    Breeding may occur more than once yearly, but little definitive information is available.
  • Breeding season
    Mating occurs throughout the year but is concentrated in early summer.
  • Range number of offspring
    8 to 14
  • Average gestation period
    14 days
  • Average age at sexual or reproductive maturity (female)
    6 months
  • Average age at sexual or reproductive maturity (male)
    6 months

There is little information regarding parental investment in T. canescens. However, similar to other marsupials, young are born very underdeveloped and must stay close to their mother in order to develop fully (Eisenberg, 1989).

In a closely related species, Marmosa robinsoni, weaning does not take place until the young are 60-70 days old (Nowak, 1991). Also, young stay attached to the teat for up to 30 days (Eisenberg, 1989). (Eisenberg, 1989; Nowak, 1991)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female


There is little information regarding the lifespan of T. canescens. In related species belonging to the genus Marmosa, such as Marmosa robinsoni, life expectancy is typically under 1 year of age in the wild and up to 3 years in captivity (Nowak, 1991). (Nowak, 1991)

  • Range lifespan
    Status: captivity
    3 (high) years
  • Typical lifespan
    Status: wild
    1 (high) years
  • Average lifespan
    Status: wild
    <1 years


Tlacuatzin canescens is a solitary, nocturnal species (Ceballos, 1990). Densities of this animal range between 0.4 to 4.5 individuals per hectare (Zarza, Ceballos and Steele, 2003). Grayish mouse opossums are semi-arboreal and, in comparison to related species in the genus Marmosa, they spend much more time on the ground (Zarza, Ceballos and Steele, 2003). When Marmosa species come into contact with one another, they are courageous fighters (Nowak, 1991). (Ceballos, 1990; Nowak, 1991; Zarza, et al., 2003)

Home Range

Home ranges for T. canescens have not yet been reported. However, one study indicated that individuals had moved up to 72 meters between successive captures, with an average of 35.2 meters (Zarza, Ceballos and Steele, 2003). (Zarza, et al., 2003)

Communication and Perception

Communication between T. canescens individuals of the same sex is almost always agonistic and they often times hiss at one another (Eisenberg, 1989). Males attempt to attract females through the use of clicking sounds (Eisenberg, 1989). Before copulation, males and females communicate through the exchange of loud noises, which lasts for approximately three minutes (Zarza, Ceballos and Steele, 2003). (Eisenberg, 1989; Zarza, et al., 2003)

Food Habits

Tlacuatzin canescens is omnivorous (Zarza, Ceballos and Steele, 2003). Members of this species feed primarily on insects. Specifically, T. canescens eat praying mantises, cerambycid beetles and scarabiid beetles (Zarza, Ceballos and Steele, 2003). This species also preys upon geckos, bird eggs, bird nestlings and fledglings, coconut, banana, small rodents and figs (Nowak, 1991; Zarza, Ceballos and Steele, 2003). (Nowak, 1991; Zarza, et al., 2003)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • eggs
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit


Known predators for Tlacuatzin canescens include pumas, and barn owls (Zarza, Ceballos and Steele, 2003). There is little information on anti-predator adaptations of T. canescens. Their cryptic coloration and nocturnal habits may be their primary defenses. (Loomis and Stephens, 1962; Zarza, et al., 2003)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Tlacuatzin canescens individuals are hosts for the chigger species Eutrombicula batatas. No other parasites have been recorded for this species. Tlacuatzin canescens is a prey item for cougars and barn owls. Geckos are occasionally eaten by T. canescens, which may affect their populations. (Loomis and Stephens, 1962; Zarza, et al., 2003)

Tlacuatzin canescens lives sympatrically with various other small mammals, including Baiomys taylori, Hodomys alleni, Neotoma mexicana, Oryzomys palustris and Megasorex gigas. Since T. canescens regularly eats fruits such as coconut, figs, bananas and oranges, it is likely that they act as seed dispersers. (Zarza, et al., 2003)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species
  • chigger Eutrombicula batatas

Economic Importance for Humans: Positive

There is little information about the positive economic influence Tlacuatzin canescens has on humans.

Economic Importance for Humans: Negative

It is unlikely that T. canescens has a negative impact on humans.

Conservation Status

According to the IUCN Red List, there is not enough data available for T. canescens to determine its conservation status. Some researchers have remarked that T. canescens is quite common and is in no danger of becoming extinct. However, there is an island population off the coast of Mexico where the introduction of a new species (Rattus rattus) has negatively impacted the size of the T. canescens population (Zarza, Ceballos and Steele).

Deforestation is a problem for many neotropical species (Sanchez-Cordero et al., 2005). The general consensus, however, is that T. canescens is not immediately threatened by people or deforestation due to its small size and nocturnal behavior (Nowak, 1991). (Nowak, 1991; Sanchez-Cordero, et al., 2005; Zarza, et al., 2003)

Other Comments

Recent phylogenetic studies have indicated that T. canescens is genetically distinct from other Marmosa species and therefore should be placed into a new genus, Tlacuatzin. They were previously recognized as Marmosa canescens. (Voss and Jansa, 2003)


Tanya Dewey (editor), Animal Diversity Web.

Sarah Segerlind (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.



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

World Map


uses sound to communicate


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.


Referring to an animal that lives in trees; tree-climbing.

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.


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


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


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


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.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


chemicals released into air or water that are detected by and responded to by other animals of the same species


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


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.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.


remains in the same area


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


lives alone


uses touch to communicate


Living on the ground.


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.


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.


uses sight to communicate


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


Ceballos, G. 1990. Comparative Natural History of Small Mammals from Tropical Forests in Western Mexico. Journal of Mammalogy, 71 (2): 263-266. Accessed March 11, 2006 at

Eisenberg, J. 1989. Mammals of the Neotropics. Chicago: University of Chicago Press.

Loomis, R., R. Stephens. 1962. Marmosa canescens in Sonora, Mexico. Journal of Mammalogy, 43: 111. Accessed March 19, 2006 at

Nowak, R. 1991. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.

Sanchez-Cordero, V., P. Illoldi-Rangel, M. Linaje, S. Sarkar, A. Peterson. 2005. Deforestation and extant distributions of Mexican endemic mammals. Biological Conservation, 126: 465-473. Accessed March 11, 2006 at

Voss, R., S. Jansa. 2003. Phylogenetic Studies on Didelphid Marsupials II. Nonmolecular Data and New IRBP Sequences: Seperate and Combined Analyses of Didelphine Relationships with Denser Taxon Sampling. Bulletin of the American Museum of Natural History, 276: 1-82. Accessed March 11, 2006 at

Zarza, H., G. Ceballos, M. Steele. 2003. Marmosa canescens. American Society of Mammalogists, 725: 1-4. Accessed February 02, 2006 at