Geographic Range
Conover's tuco-tucos are endemic to the Chaco in both Bolivia and Paraguay, occurring
at an altitude of 250 m. They are found from 20 degrees S to 23 degrees S and 60
degrees to 63 degrees. This species has one of the smallest ranges of the thirty-eight
currently recognized species in the genus
Ctenomys
. As a genus, tuco-tucos are considered to exhibit considerable ecologic plasticity.
The fossil record dates back to the Pliocene in this range. Currently, it is thought
that a vicariant event cannot explain present distributions.
- Biogeographic Regions
- neotropical
Habitat
Ctenomys concoveri
is a primarily fossorial species. Conover's tuco-tucos are found in areas of sandy
or loamy soils. In the Paraguayan Chaco, the landscape is primarily savannah grassland
and shrub forest. The shrub forest is characterized by thorny bushes, shrubs, and
cacti, with scattered trees up to 13 m high. The dominant species in the forest include
Prosopis ruscifolia
, a thorny legume, and
Opuntia
sp. Much of the grassland is under severe agricultural pressure.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- scrub forest
- Other Habitat Features
- agricultural
Physical Description
Conover's tuco-tucos are large for this genus, and can reach weights in excess of 1 kg. This species strongly resembles North American pocket gophers ( Geomyidae ). As a fossorial species, they have a robust and cylindrical body, large head, short and sparsely haired tail, and short, muscular neck and forelimbs. The eyes are medium-sized and positioned to enable these animals to look out of the burrow without exposing the whole body. The external ears are very small, another adapation to fossorial living. The forelimbs are slightly shorter than the hindlimbs, and all digits have claws. The claws on the forefeet are the longest, and are used for loosening packed earth.
The skin seems loosely applied to the body, possibly making it easier for these animals
to turn around in narrow burrows. The soles of the hind feet are equipped with comb-like
bristles, composed of hair fringes, and are used to groom dirt from the fur.
Conover's tuco-tucos have a tan dorsum with a faint mid-dorsal line. The top of the
head is a gray-brown, lightening to flecking on the back of the head. The cheeks
are a brownish-yellow, and touches of white surround the mouth and chin. The ventrum
is also a light yellow. Generally, the fur is thick and long.
Like other
Ctenomys
, Conover's tuco-tucos have a broad, flattened skull. They lack a sagittal crest
but have prominent ridges along the parietals. The zygomatic arches are strongly
bowed outward, and the jugal bone does not contact the lacrimal bone. They are equipped
with large auditory bullae and large paroccipital processes. The dental formula is
1/1, 0/0, 1/1, 3/3 = 20.
Ctenomys concoveri
is noted for prominent broad and heavy proodont incisors; each of the anterior surfaces
has an inner and outer wide lateral groove and three shallow, narrow median grooves.
These incisors, covered by a bright orange enamel, are used to gnaw roots when digging.
This species also has kidney-shaped hypsodont molars for chewing vegetation, with
the last molar being reduced.
Although males are reported to be larger than females, the following measurements
apply to both sexes. Total length of these animals ranges from 338 to 442 mm (average
= 403.3 mm); head and body length varies from 245 to 328 mm (average = 293.3 mm);
tail length ranges between 93 and 137 mm (average = 110.0 mm); hindfoot length is
between 52 and 62 mm (average = 58.0 mm); and ear length (notch to tip) is between
10 and 16 mm (average = 13.4 mm). The average adult weighs about 900 grams.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Sexual size dimorphism and enlarged testes are observed in this and other
Ctenomys
species, suggesting polygynyis the primary mating system.
- Mating System
- polygynous
Female
C. conoveri
are monoestrus, bearing one litter per year. They construct lined nest chambers,
typically below the level of the main tunnel.
Gestation length is not available for this species, but other species in the genus
Ctenomys
range from about 102 to 120 days. Litters range in size from 1 to 7 young. Young
of this genus may be born at varying levels of altriciality. Some young are precocious,
coming out fully furred and looking like miniature adults. Others are only slightly
furry at birth, and may have their eyes closed. The condition of
C. concoveri
at birth has not been reported.
Young of
Ctenomys talarum
are reportedly able to fend for themselves by about 10 days of age, even though they
are not the most precocious members of their genus at birth. Nursing is said to continue
for 5 weeks, and sexual maturity is reached sometime around 8 months of age, for both
males and females. It is likely that
C. concoveri
is similar.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- viviparous
Ctenomys conoveri
has altricial young. The females are generally responsible for care and feeding
of the young. Male parental care has not been reported.
- Parental Investment
- no parental involvement
- altricial
-
pre-fertilization
-
protecting
- female
-
protecting
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
protecting
- female
-
protecting
Lifespan/Longevity
The mean lifespan in the wild for Conover's tuco-tucos is probably less than three
years, as they are an important prey species in the Chaco.
Behavior
Conover's tuco tucos are noted for building complex, branching tunnel systems, which
include nesting chambers and other specialized chambers for food storage. At times
the actual burrow openings are plugged, perhaps to deter predators. Most tunnels
average 14 m long, 5 to 7 cm wide, and 30 cm below the surface. As a fossorial species,
C. conoveri
uses its strong incisors and hind limbs to excavate burrows. They most often dig
during daylight hours, especially early morning and late afternoon. When threatened,
they may back rapidly into the burrow, using their almost hairless tail as a sensory
apparatus.
Home Range
The size of the home range of this species has not been reported.
Communication and Perception
Conover's tuco-tucos, like all other tuco-tucos, earned their common name in part
for the alarm call emitted by males due to territoriality or fear. The calls last
10 to 20 seconds, beginning at a slow rate and increasing throughout. In reality,
the sound is more of a "tloc tloc tloc" than a "tuco tuco."
Although details are not available, it is also likely that these animals communicate with one another through visual signaling. They also are likely to have tactile communication, especially between mates, parents and offspring, and rivals.
Food Habits
Ctenomys conoveri
is entirely vegetarian, feeding on roots, stems, and grasses of the Chacoan region.
Its preference for plant material makes it a pest because of damage to cultivated
crops--much like the North American pocket gophers (Geomyidae). It builds separate
food burrows for food storing.
- Plant Foods
- leaves
- roots and tubers
- Foraging Behavior
- stores or caches food
Predation
As rodents in the Chacoan ecosystem,
C. conoveri
serve as an important food item for many predators, including owls, diurnal raptors,
carnivorous mammals such as the maned wolf and the pampas fox, and feral cats. The
males are aposematic, meaning that they elicit alarm calls as an antipredatory adaptation;
additionally, the placement of the eyes allows these animals to look out of their
burrows without exposing the rest of the body.
- Anti-predator Adaptations
- aposematic
Ecosystem Roles
The strong foraging habits of Conover's tuco-tucos have been crucial to maintaining
habitat openings and providing regrowth forage for wild and domestic ungulates; They
also aerate the soil through their burrowing behaviors. They present vital habitat
via burrows to many species of mammals, lizards, toads, invertebrates, and, at times,
birds. They are also a prey species for a viariety of raptors and carnivorous mammals.
- Ecosystem Impact
- creates habitat
- soil aeration
Economic Importance for Humans: Positive
Although often unrecognized, Conover's tuco-tucos do provide positive services for
humans. Through their burrowing habits, they maintain wildlife habitat, which assists
resource managers and ecotourists. Their excrement also provides a fertilizer for
the soil and crops. Similarly, their burrowing habits may aid agriculturists in aerating
and maintaining the soil. Their foraging habits oftentimes stimulate faster plant
growth rather than halting it. More research is being conducted on them as interest
in the Chacoan ecosystem and
Ctenomys
species continues to grow. They are also becoming more commonly listed on many pet
trade web pages.
- Positive Impacts
- pet trade
Economic Importance for Humans: Negative
Similar to the prairie dog controversy in the American west, Conover's tuco-tucos
create burrows that damage agricultural and graze areas. Additionally, as herbivores,
they have done a lot of agricultural damage through their preference for roots, stems,
and grasses. Many people believe their burrows result in injury and death for livestock,
while others feel their foraging habits outcompete domestic livestock.
- Negative Impacts
- crop pest
Conservation Status
Conservation efforts for this taxa are frought with taxanomic dispute and disregard
for them by ranchers. Differentiation of the genus
Ctenomys
was historically based on pelage and morphological differences; it is now shifting
to DNA and molecular sequencing, due to their substantial chromosomal variation.
This species is highly understudied and misunderstood by local inhabitants. They
are often persecuted by people, and desire and funding to study this species is often
low. Conover's tuco tucos are not listed by CITES or IUCN.
Other Comments
Old classification of this species placed it in the genus
Chacomys
.
Additional Links
Contributors
Nancy Shefferly (editor), Animal Diversity Web.
Katie Brashear (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- 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.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- agricultural
-
living in landscapes dominated by human agriculture.
- polygynous
-
having more than one female as a mate at one time
- 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).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
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.
- fossorial
-
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- 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
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- aposematic
-
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
- soil aeration
-
digs and breaks up soil so air and water can get in
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- 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.
- 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.
References
Barlow, J. 1969. Observations on the Biology of Rodents in Uruguay:Science Contribution Number 75 . Royal Ontario Museum of Life Science.
Brooks, D. 2002. "Chaco (NT0210)" (On-line ). World Wildlife Fund. Accessed 12/09/02 at http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0210_full.html .
Cook, J., T. Yates. 1994. Systematic relationships of the Bolivian tuco-tucos, genus *Ctenomys*. Journal of Mammalogy , 75: 583-599.
Eisenberg, J., K. Redford. 1992. Mammals of the Neotropics: Volume 2 . Chicago: Univeristy of Chicago Press.
Myers, P. 1999. "Ctenomyidae" (On-line ). Animal Diversity Web. Accessed 10/16/02 at http://animaldiversity.ummz.umich.edu/chordata/mammalia/rodentia/ctenomyidae.html .
Nowak, R. 1991. Walker's Mammals of the World, Fifth Edition . Baltimore: Johns Hopkins University Press.
Wilson, D., D. Reeder, C. Woods. 1993. Mammal Species of the World: a Taxanomic and Geographic Reference; Second Edition . Washington, DC: Smithsonain Institution Press.