Tuco-Tucos: Ctenomyidae

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TUCO-TUCOS: Ctenomyidae

PEARSON'S TUCO-TUCO (Ctenomys pearsoni): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Tuco-tucos are small to medium-sized rodents with heavily built bodies, strong and large heads, and short, powerful legs. Their general appearance is that of the pocket gopher (Geomyidae), found in North America. The head and body length is 8.6 to 16.9 inches (22 to 53 centimeters) and they weigh from 3.5 ounces to 2.4 pounds (100 grams to 1.1 kilograms). Their skin is loose on their bodies, making it easier for them to turn around in their narrow burrows. They have tiny ears and short, stiff, hairless tails. The front paws of tuco-tucos are longer than the hind legs.

They have very distinct bright orange incisors, the two long, flat, sharp teeth at the front of the mouth, that are wide and powerful. Their fur is thick and long. It varies in color between species, including different shades of cream, red, brown, gray and black. The upper body fur is generally darker than the lower body fur.

GEOGRAPHIC RANGE

Central and southern South America, including Argentina, Bolivia, Brazil, Chile, Paraguay, Peru, and Uruguay.

HABITAT

Tuco-tucos range from the tropics to the sub-Antarctic regions at the tip of South America. They seem to prefer coastal areas, grassland, rainforest, deciduous forest, the large treeless semi-arid grassy plains called steppes, and meadows. They are found from sea level up to 13,120 feet (4,000 meters) in the Andes Mountains.

Most species live in a very small geographic area, including the Bolburn's tuco-tuco and the silky tuco-tuco that inhabit extreme southwestern Argentina. There are only several species that have a wider geographic range, such as the collared tuco-tuco, which lives in Argentina, Brazil, and Uruguay, and the highland tuco-tuco, found in Argentina, Bolivia, Chile, and Peru.

DIET

All species of tuco-tucos are believed to be herbivores, meaning they are plant-eaters. Their primary food sources are roots, grasses, herbs, and shrubs.

BEHAVIOR AND REPRODUCTION

Tuco-tucos are extremely solitary animals and are found in pairs only when mating. The one known exception is the social tuco-tuco, found in Argentina, which lives in colonies. They are diurnal, meaning they are most active during the day, and polyrhythmic, meaning they alternate between short periods of activity and resting throughout the day.

Tuco-tucos build burrows that are an intricate system of connecting tunnels and small caverns. The main tunnel is about 46.2 feet (14 meters) long, about 2 to 2.8 inches (5 to 7 centimeters) wide, and 12 inches (30 centimeters) below the surface. The burrow usually contains a grass-lined chamber for nesting, and several chambers for storing food. At least two species, the talas tuco-tuco and collared tuco-tuco, keep the temperature of their borrows at 68 to 71.6°F (20 to 22°C) by blocking and unblocking their burrow entrances based on sun and wind.

GOOD DIGGERS

Tuco-tucos are natural diggers. They prefer soil that is sandy or loamy, meaning it is a fertile mixture of clay, sand, silt, and other organic matter. They live in burrows that they dig. These burrows are very long and usually have several branching tunnels, along with many entrances and exits, usually concealed with plant material or plugged with rocks. Within these tunnels, they dig chambers for nesting and storing food. Tuco-tucos dig with their incisors, the two long, flat, sharp teeth at the front of their mouths, and kick the dirt out of the tunnel with their strong hind legs.

Tuco-tucos use sounds, smells, and touch to communicate with each other. The name "tuco-tuco" is an attempt by native South Americans to express in words the sound that several species of tuco-tuco make when they are giving a warning to animals that invade their territory. The actual sound is more like "tloc-tloc." Tuco-tucos have several other sounds including a deep rumbling noise made by the male when courting a female.

Tuco-tucos have one or two mating periods each year where the female produces a litter of babies. The gestation period, the time they carry their young in the womb, varies from species to species but generally is 100 to 120 days. Litter sizes vary from one to seven babies, called pups. Males and females reach are sexually mature, able to mate, at about eight months. The average lifespan of a tuco-tuco in the wild is about three years.

TUCO-TUCOS AND PEOPLE

Tuco-tucos are hunted for their meat by several native South American groups, including the Tehuelches and Onas. Farmers who consider them an agricultural pest because they eat crops often kill them. They can also cause problems for horseback riders when their burrows cave in under the weight of the horses, causing broken legs to the horses and often injury to the riders when they fall.

CONSERVATION STATUS

The Magellanic tuco-tuco is listed as Vulnerable, facing a high risk of extinction, by the IUCN due to declining habitat. In southern Patagonia, an area of Argentina between the Andes Mountains and the south Atlantic Ocean, extensive grazing by sheep on grasses and plants eaten by the highland tuco-tuco and other agricultural activities, have caused the animal to become rare and endangered. Three species are listed as Near Threatened, at risk of becoming threatened, by the IUCN: mottled tuco-tuco, Natterer's tuco-tuco, and social tuco-tuco. No other species are listed as threatened by the IUCN.

PEARSON'S TUCO-TUCO (Ctenomys pearsoni): SPECIES ACCOUNT

Physical characteristics: The head and body length for Pearson's tuco-tuco is 7.5 inches (19 centimeters) and they weigh about 7 ounces (200 grams). They have brown-red fur with a white band of fur under the neck and white patches on the sides of the neck.

Geographic range: Pearson's tuco-tucos live in Peru, Chile, south-west Uruguay, and Entre Rios province in Argentina.

Habitat: These tuco-tucos prefer coastal sand dunes and grassland.

Diet: Pearson's tuco-tuco are herbivores. Their diet consists primarily of grasses, herbs, shrubs, and roots.

Behavior and reproduction: The Pearson's tuco-tuco is solitary and individuals come together only to mate. The animal is territorial, meaning it is protective of an area it considers home and claims exclusively for itself. It will aggressively defend its territory and burrow from other tuco-tucos. It leaves its burrow only to find food and to mate. It has several vocalizations, including a sound to warn intruders away from its territory. It also has an excellent sense of hearing and can detect a human moving from about 165 feet (50 meters) away.

The mating season for Pearson's tuco-tuco in Peru is during the dry season and the babies are born in the wet season, when there is an abundance of plants. Female Pearson's tuco-tucos have one litter of babies per year. The number of babies ranges from two to four. They are believed to be polygamous, meaning they take more than one mate during the breeding season.

Pearson's tuco-tuco and people: They are rarely hunted and because they are so solitary, they have no known significance to humans.

Conservation status: Pearson's tuco-tuco is not listed as threatened by the IUCN. ∎

FOR MORE INFORMATION

Books:

Macdonald, David. The New Encyclopedia of Mammals. Oxford, U.K.: Oxford University Press, 2001.

Nowak, Ronald M. Walker's Mammals of the World, 6th ed. Baltimore: Johns Hopkins University Press, 1999.

Redford, Kent H., and John F. Eisenberg. Mammals of the Neotropics: The Southern Cone, Chile, Argentina, Uruguay, Paraguay. Chicago: University of Chicago Press, 1992.

Wilson, Don E., and DeeAnn M. Reeder. Mammal Species of the World— A Taxonomic and Geographic Reference, 2nd ed. Washington, DC: Smithsonian Institution Press, 1993.

Periodicals:

"Social Tuco-tucos Develop More Variety." Science News (August 26, 2000): 143.

El Jundi, Tarik A. R. J., and Thales R. O. De Freitas. "Genetic and Demographic Structure in a Population of Ctenomys lami (Rodentia-Ctenomyidae)." Hereditas (February 2004): 18–23.

Lacey, Eileen A., and John R. Wieczorek. "Ecology of Sociality in Rodents: A Ctenomyid Perspective." Journal of Mammalogy (November 2003): 1198–1211.

Lessa, Enrique P., and Joseph A. Cook. "The Molecular Phylogenetics of Tuco-Tucos (Genus Ctenomys, Rodentia: Octodontidae) Suggests an Early Burst of Speciation." Molecular Phylogenetics and Evolution (February 1998): 88–99.

Schwartz, Lisa E., and Eileen A. Lacey. "Olfactory Discrimination of Gender by Colonial Tuco-Tucos (Ctenomys sociabilis.)" Mammalian Biology (January 2003): 53–60.