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Ctenomys talarumTalas tuco-tuco

By Nicholas Jurich

Geographic Range

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, et al., 2003)

Habitat

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)

Physical Description

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, et al., 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, et al., 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, et al., 2003)

  • Sexual Dimorphism
  • male larger
  • Range mass
    0.090 to 0.190 kg
    0.20 to 0.42 lb
  • Average mass
    0.133 kg
    0.29 lb
  • Range length
    212.0 to 254.0 mm
    8.35 to 10.00 in
  • Average length
    233.4 mm
    9.19 in
  • Range basal metabolic rate
    1.08 to 2.00 cm3.O2/g/hr

Reproduction

Ctenomys talarum clearly recognizes interspecific chemical signals from cues in urine, feces, and soiled wood shavings. Each sex distinguishes the scents of same and other sexes. Furthermore, C. talarum identifies the reproductive status of individuals of the opposite sex and selects mates via such chemical cues. (Zenuto and Fanjul, 2002; Zenuto, et al., 2004)

Mating behaviors of C. talarum depend a great deal on 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 the spacing of individual males within the area. (Redford and Eisenberg, 1992)

Paternity tests using DNA analysis and analyses of testes size have shown that C. talarum is polygynous. In these studies, a single male was found to have sired offspring litters with multiple females. (Zenuto, et al., 1999a; Zenuto, et al., 1999b)

Usually, C. talarum is solitary, and only one individual inhabits each burrow. However, during the breeding season, males and females are often found together in the same burrow. (Redford and Eisenberg, 1992)

Male Talas tuco-tucos have extended reproductive availability, covering most of winter and into summer. Females are more restricted in their breeding availability. Talas tuco-tucos have two reproductive periods, interrupted by an inactive period of 6 to 8 months. All males are reproductive in July, and the majority of pregnancies occur in August. During the breeding season, the mean prevalence of pregnancy is 0.66. (Justo, et al., 2003)

Most births occur between October and December, and average litter size is between 4 and 5 offspring. The energetic costs of gestation and lactation are similar, although the gestation period is twice as long as that of lactation. When young are about 30 days old, females refuse to allow suckling. Females exhibit postpartum estrus, and it is possible that a female may be pregnant and lactating at the same time. At the point of sexual maturity, the average weights of females and males are 137.52 g and 176.62 g, respectively. Females tend to maintain a constant weight after reaching maturity. (Busch, et al., 1989; Zenuto, et al., 2002)

In captivity, the age of first reproduction is eight months, and females come into estrus two times per year. Captive C. talarum has an average gestation period of 102 days and a mean litter size of 5 offspring, with a range of between 1 and 7 individuals. (Redford and Eisenberg, 1992)

  • Breeding interval
    The reproductive cycle for C. talarum is bimodal, with two litters produced per year. An inactive period of 6 to 8 months separates these episodes.
  • Breeding season
    Although males are reproductively capable for nearly eight months of the year, the breeding season for females is much more restricted. The majority of mating episodes occur in the months of July and August.
  • Range number of offspring
    4.000 to 5.000
  • Average number of offspring
    4.55
  • Average number of offspring
    4
    AnAge
  • Average gestation period
    102 days
  • Average gestation period
    102 days
    AnAge
  • Average weaning age
    30 days
  • Average time to independence
    60 days
  • Range age at sexual or reproductive maturity (female)
    6 to 8 months
  • Range age at sexual or reproductive maturity (male)
    6 to 8 months

Apart from the mating episode, male and female Ctenomys talarum do not interact. Thus, females are responsible for all aspects of caring for offspring. Male C. talarum provide no prenatal or parental care. (Zenuto, et al., 2002)

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

Lifespan/Longevity

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; 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, et al., 2003)

Behavior

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, et al., 2003)

  • Range territory size
    7.9 to 15.6 m^2

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)

Communication and Perception

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, et al., 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)

Food Habits

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, et al., 2003; Justo, et al., 2003)

  • Plant Foods
  • leaves
  • roots and tubers

Predation

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, et al., 2003; Rossin, et al., 2004; Weir, 1971)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

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, et al., 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, et al., 2004)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

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

  • Negative Impacts
  • crop pest

Conservation Status

There are no known conservation efforts for Ctenomys talarum.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Nicholas Jurich (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), 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

acoustic

uses sound to communicate

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

cryptic

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.

diurnal
  1. active during the day, 2. lasting for one day.
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.

folivore

an animal that mainly eats leaves.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

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).

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.

polygynous

having more than one female as a mate at one time

scent marks

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

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

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.

savanna

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.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Busch, C., A. Malizia, O. Scaglia, O. Reig. 1989. Spatial Distribution and Attributes of a Population of Ctenomys talarum (Rodentia: Octodontidae). Journal of Mammalogy, 70 (1): 204-208.

Cutrera, A., C. Antinuchi. 2004. Fur changes in the subterranean rodent Ctenomys talarum: possible thermal compensatory mechanism. Revista Chilena de Historia Natural, 77 (2): 235-242.

Justo, E., L. De Santis, M. Kin. 2003. Ctenomys talarum. Mammalian Species, No. 730: pp. 1-5. Accessed February 01, 2006 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/default.html.

Lacey, E., S. Braude, J. Wieczorek. 1997. Burrow Sharing by Colonial Tuco-Tucos (Ctenomys sociabilis). Journal of Mammalogy, 78 (2): 556-562.

Redford, K., J. Eisenberg. 1992. Mammals of the Neotropics, Volume 2, The Southern Cone: Chile, Argentina, Uruguay, Paraguay. Chicago and London: The University of Chicago Press.

Rossin, A., A. Malizia, G. Denegri. 2004. The role of the subterranean rodent Ctenomys talarum (Rodentia: Octodontidae) in the life cycle of Taenia taeniaeformis (Cestoda: Taeniidae) in urban environments. Veterinary Parasitology, 122 (1): 27-33.

Schleich, C., C. Antinuchi. 2004. Testing Magnetic Orientation in a Solitary Subterranean Rodent Ctenomys talarum (Rodentia: Octodontidae). Ethology, 110: 485-495.

Weir, B. 1971. A Trapping Technique for Tuco-Tucos, Ctenomys talarum. Journal of Mammalogy, 52 (4): 836-839.

Zenuto, R., C. Antinuchi, C. Busch. 2002. Bioenergetics of Reproduction and Pup Development in a Subterranean Rodent (Ctenomys talarum). Physiological and Biochemical Zoology, 75 (5): 469-478.

Zenuto, R., M. Fanjul. 2002. Olfactory Discrimination of Individual Scents in the Subterranean Rodent Ctenomys talarum (Tuco-Tuco). Ethology, 108: 629-641.

Zenuto, R., M. Fanjul, C. Busch. 2004. Use of Chemical Communication by the Subterranean Rodent Ctenomys talarum (Tuco-Tuco) During the Breeding Season. Journal of Chemical Ecology, 30 (11): 2111-2126.

Zenuto, R., E. Lacey, C. Busch. 1999. DNA Fingerprinting Reveals Polygyny in the Subterranean Rodent Ctenomys talarum. Molecular Ecology, 8: 1529-1532.

Zenuto, R., A. Malizia, C. Busch. 1999. Sexual Size Dimorphism, Testes Size and Mating System in Two Populations of Ctenomys talarum (Rodentia: Octodontidae). Journal of Natural History, 33: 305-314.

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