Tlacuatzin canescens
gray mouse opossum
(Also: grayish mouse opossum)

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, Ceballos, and Steele, 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, Ceballos, and Steele, 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, Ceballos, and Steele, 2003)

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, Ceballos, and Steele, 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, Ceballos, and Steele, 2003)

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)

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, Ceballos, and Steele, 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, Ceballos, and Steele, 2003)

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, Ceballos, and Steele, 2003)

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, Ceballos, and Steele, 2003)

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, Ceballos, and Steele, 2003)

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, Ceballos, and Steele, 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, Ceballos, and Steele, 2003)

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

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

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, Ceballos, and Steele, 2003)

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)