Ctenomys talarum
Talas tuco-tuco

Ctenomys talarum is a South American rodent found only in eastern Argentina. They are also known as Talas tuco-tucos. Three subspecies are morphologically similar and are distinguished only by the specific region which each occupies: C. t. occidentalis along the eastern border of the province of La Pampa; C. t. recessus along the southern coast; and C. t. talarum along the eastern coast of the province of Buenos Aires. (Justo, De Santis, and Kin, 2003)

Talas tuco-tucos spend most of their lives in underground burrows, which can be found in pastures with flat terrain. Burrows have a branching structure, measure 6 to 8 cm in diameter, are shorter than 25 m in length, and are at least 30 cm in depth. Compared to neighboring sympatric species C. australis, C. talarum prefers firmer, more organic soils, which tend to host a denser composition of vegetation. (Redford and Eisenberg, 1992; Schleich and Antinuchi, 2004)

Ctenomys talarum has a cylindrical body, reduced neck, and short tail. Mean total length ranges from 212.0 to 254.0 mm, mean length of head and body is 167.5 mm, and the mean tail length is 66.7 mm. The mean skull length and mean nasal length are 37.4 mm and 11.9 mm, respectively. The average breadth of braincase for C. talarum is 14.6 mm. Males and females have mean masses of 186.0 g and 128.0 g, respectively, while the average mass for all recorded individuals is 133.0 g. Baculum is small and narrow, with a mean length and proximal and distal breadth of 6.4 mm, 1.32 mm, and 0.9 mm, respectively. (Justo, De Santis, and Kin, 2003; Redford and Eisenberg, 1992)

The short, fine hair of C. talarum is dark grey to black dorsally, blending to reddish-brown laterally and cream ventrally. Distinct white patches are found at the base of each ear, as well as in the inguinal and axillary areas. The tail is brown and dark grey. Hind feet have white, bristle-like hairs, and both front and hind feet have long, curved claws. Both eyes and ears are small. Cteonmys talarum molts during the summer and autumn seasons. Some intersexual differences exist in the five-phase molt; females molt earlier than males. (Justo, De Santis, and Kin, 2003; Redford and Eisenberg, 1992)

Ctenomys talarum is distinguished from closely related species in that it is, by measure of total length, smaller than C. azarae, C. australis, and C. mendocinus. Tail length of C. talarum is also noticeably smaller than that of C. australis and C. mendocinus. Compared to C. azarae, C. talarum has short and broad nasals. Ctenomys talarum is distinguished from C. minutus and C. torquatus by its smaller, flatter baculum. (Justo, De Santis, and Kin, 2003)

In wild populations, the overall mortality rate of C. talarum is 0.05 per week. The probability of survival during the winter (March to October) is 0.19, while the probability of survival during the summer (October to March) is 0.38. With a lifespan of 20 to 22 months, individuals rarely live through more than two reproductive seasons. (Busch et al., 1989)

In captivity, Ctenomys talarum develops hyperglycemia and cataracts. As much as 40% of individuals in a colony show deteriorative eye change. Blood sugar levels may increase nearly 75%. (Justo, De Santis, and Kin, 2003)

Talas tuco-tucos are solitary, only one individual occupies a burrow, and males and females distribute themselves uniformly over an area in high-density populations. A population density of 207 individuals per hectare has been observed in grazed pasture. Other studies have found that smaller populations have aggregated distributions, with several adult females and a single male in relatively close proximity. (Busch et al., 1989; Redford and Eisenberg, 1992)

As a mean of thermoregulation, the pelage of C. talarum varies seasonally. Both ventral and dorsal fur is significantly shorter and ventral fur is less dense during the warm season. This fur change serves to facilitate heat loss in the tunnel environment. Additionally, pregnant and lactating female C. talarum show increasingly less dense ventral fur, which allows them to more effectively conduct heat to newly-born offspring in the nest. (Cutrera and Antinuchi, 2004)

It was hypothesized that Talas tuco-tucos, like several other subterranean rodents, have the ability to spatially orient through perception of the earth’s magnetic field. Research did not support this hypothesis. (Schleich and Antinuchi, 2004)

The presence of a thick medulla on the kidneys means that Talas tuco-tucos can excrete highly concentrated urine and do not need free water for drinking. (Justo, De Santis, and Kin, 2003)

Home Range

The mean home-range size of males is 12.3 square meters, and that of females is 8.7 square meters. (Busch et al., 1989)

Although Talas tuco-tucos are fairly solitary animals, spatial organization within a population is socially important. They clearly recognize odors from urine, feces, and wood shavings from other individual members of the population. Scent recognition helps to uniformly distribute burrows within a specific area. In addition to being spatial cues, these sex distinctions are significant in mating behavior. (Justo, De Santis, and Kin, 2003)

Talas tuco-tucos also communicate with vocalizations. Only males produce the “tuc” sound, which gives rise to the common name of the family (tuco-tuco). The song consists of multiple “tuc” sounds, lasts roughly ten to twenty seconds, and serves to establish spatial organization. This means of communication is also implicated in mating behavior. (Redford and Eisenberg, 1992)

Talas tuco-tucos are herbivorous, feeding on roots and grasses. Unlike most subterranean rodents, Talas tuco-tucos leave their burrows to forage for vegetation above ground. Captive C. talarum preferentially consume the grass species Bromus unioloides. (Justo, De Santis, and Kin, 2003)

Talas tuco-tucos are preyed on by several species of carnivorous birds, including Athene cunicularia, Asio flammeus, and Tyto alba. Predators also include several carnivore species, such as Galictis cuja and Leopardus geoffroyi. Near urban areas, domestic cats and domestic dogs prey on Talas tuco-tucos. The primary predator-avoidance strategies include cryptic fur coloration and the ability to dig rapidly and efficiently close openings to their underground tunnels. (Justo, De Santis, and Kin, 2003; Rossin, Malizia, and Denegri, 2004; Weir, 1971)

This species is an herbivore. Its grazing activities and burrowing impact the composition of plant communities where it lives.

Ctenomys talarum is parasitized by several families of the order Nematoda, as well as several lice species, such as Eulinognathus americanus, Gyropus parvus, and Phtheropoios forficulatus. Although prevalence of parasitism does not differ between sexes of C. talarum, the intensity does vary. (Justo, De Santis, and Kin, 2003)

In populations near urban areas of the Buenos Aires Province, C. talarum is an intermediate host of the cestode parasite Taenia taeniaeformis. A prevalence of 64% in some populations indicates that C. talarum is an important host to the parasite, whose final host is domestic dogs, a common predator of C. talarum in urban areas. (Rossin, Malizia, and Denegri, 2004)

The mounds and burrows of C. talarum bare and erode soils in some agricultural areas. (Justo, De Santis, and Kin, 2003)

There are no known positive effects of Ctenomys talarum on humans.

There are no known conservation efforts for Ctenomys talarum.