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Cynomys ludovicianusblack-tailed prairie dog

By Nancy Shefferly

Geographic Range

Cynomys ludovicianus occupies narrow bands of short to mid-grass prairies from central Texas in the south to just north of the Canadian-United States boundary. Historically, the range of black-tailed prairie dogs was greater. They were found from Nebraska in the east to Montana in the west. They ranged from Canada in the north to Mexico in the south. However, intensive efforts at eradication of these animals by ranchers have reduced the species to a few isolated populations associated mainly with protected lands. (Hoffman, 1999; Hoogland, 1995; Hoogland, 1996)

Habitat

Cynomys ludovicianus occupies a relatively restricted range of open, level, arid, short-grass plains. These prairie dogs are commonly found near river flats or in coulee bottomlands where sagebrush, greasewood, and prickly pear grow. They are never found in moist areas. (Hoffman, 1999; Hoogland, 1995; Nowak, 1999)

  • Range elevation
    1,300 to 2,000 m
    to ft

Physical Description

Cynomys ludovicianus varies in length between 352 and 415 mm. Sexual dimorphism is prevalent, with males measuring greater in total length than females (male range: 358 to 415 mm; female range: 352-375 mm). Males also tend to be between 10 and 15% heavier than females, weighing in between 850 and 1,675 g, compared to females which weigh between 705 and 1,050 g. Weight varies seasonally, with both males and females reaching their highest weights in the autumn, and lowest weights in winter. (Hoffman, 1999; Hoogland, 1996)

Black-tailed prairie dogs undergo two molts per year, with slightly different pelage coloration in each molt. The general coloration is brownish to brownish-red dorsally, with whitish fur on the ventrum. During the summer, individual hairs are mixed, with some being banded (black at the base, with a whitish band, then a cinnamon band, followed by a subterminal buff band, and a black tip), and some colored either solid black or half black. The latter type of hairs are longer than banded hairs and are interspersed in the coat. In winter, the banded hairs are different, with black at the base, followed by buff, then cinnamon, and possessing a white tip. Females have 8 grayish mammae that are visible only during pregnancy and lactation. (Hoogland, 1996)

Black-tailed prairie dogs are easily distinguished from Mexican prairie dogs because of non-overlapping geographic ranges. In addition, C. ludovicianus is easily distinguished from members of the subgenus Leucocrossuromys (including Gunnison's prairie dogs, white-tailed prairie dogs, and Utah prairie dogs). In addition to having mainly non-overlapping ranges, members of Leucocrossuromys all hibernate, have white- to gray-tipped tails, have smaller molars, and possess distinctly different territorial and antipredator vocalizations than do black-tailed prairie dogs.

  • Sexual Dimorphism
  • male larger
  • Range mass
    705 to 1,675 g
    24.85 to oz
  • Range length
    352 to 415 mm
    13.86 to 16.34 in
  • Average basal metabolic rate
    2.358 W
    AnAge

Reproduction

Mating is closely related to social structure in these animals. The typical mating pattern is polygynous, with a single male mating with multiple females in his home coterie. However, in some cases, more than one male may be resident in a single, large coterie. In these cases, females within the coterie may mate with both resident males. In such cases, the first male to copulate with the female sires more offspring than does the second. Additionally, there appears to be some communal nursing of young after the time they appear above ground, qualifying the species for status as a cooperative breeder. (Hoogland, 1995; Hoogland, 1996)

Reproduction occurs once per year, with the exact timing of mating varying with latitude. In Oklahoma, breeding takes place in January; in Colorado breeding takes place in February. Between late February and March,balck-tailed prairie dogs in South Dakota breed. Finally, those animals residing in the northern portions of the species range breed in late March and early April. Females of this species are typically sexually receptive only one day of the year. Females failing to conceive after this initial estrus sometimes enter estrus a second time about 13 days after their first estrus. (Hoogland, 1995)

Approximately 98% of matings in C. ludovicianus occur underground. This probably helps to reduce intermale competition for females. Several behaviors are associated with mating both underground and above ground. These include frequent entrance of a breeding male and estrus female into the same burrow; very high frequency of interaction between the male and female; self licking of genitals in both male and female; gathering of nesting materials by males, and transport of those materials into a burrow; and a later than normal nighttime entrance into the burrow by estrus females. In additon, male black-tailed prairie dogs have a unique vocalization that is associated only with mating behaviors. (Hoogland, 1995; Hoogland, 1996)

Gestation ranges in length from 33 to 38 days, with a mean of 34.6 days. Litter sizes ate birth range from 1 to 8 young, with a mean litter size at emergence from the burrow of 3 young. Young are altricial, being born blind, naked, and mostly helpless. Neonates measure approximately 70 mm in length, and weigh an average of 15 g. Fur is evident by the age of 3 weeks, and eyes are open by approximately 5 weeks of age. The age at weaning varies with litter size, as larger litters nurse longer than smaller litters. Lactation lasts from 37 to 51 days, with a mean of 41.3 days. The termination of lactation occurs shortly after emergence from the natal burrow, and after emergence but prior to the end of lactation, pups may nurse from females other than their own mother. (Hoogland, 1995; Hoogland, 1996)

Sexual dimorphism in size is already established by the time juveniles emerge from tehir natal burrows. Males weigh an average of 147 g at emergence and females weigh an average of 141 g. By October, males have acheived an average weight of 556 g, and females an average of 532 g. (Hoogland, 1995; Hoogland, 1996)

Females remain in their natal coterie for life, but males disperse as yearlings. This results in minimization of inbreeding. Also, adult males rarely remain within the same coterie for more than two breeding seasons, thus reducing the possibility that they will mate with their female offspring. (Hoogland, 1995; Hoogland, 1996)

The age of sexual maturity varies. Although most black-tailed prairie dogs copulate for the first time as two-year-olds, some reach maturity earlier or later. Among females, 35% breed as yearlings, 60% breed as two-year-olds, and 5% delay reproduction until they are 3 years old. Males show sexual asymmetry, being less likely than females to breed as yearlings, and more likely than females to dely reproduction until their third year. Among males, 6% breed as yearling, 70% as two-year-olds, and 24% breed in their third year. (Hoogland, 1995; Hoogland, 1996)

Female C. ludovicianus who mate do not always produce litters. Successful reproduction is positively related to female age. Only 54% of yearling females who copulate subsequently give birth, compared to 89% of females over the age of 2 years who copulated. Failure to give birth results from both failure of conception, resorption of embryos, and miscarriage of pregnancies. (Hoogland, 1995; Hoogland, 1996)

  • Breeding interval
    Females of this species are able to breed once per year.
  • Breeding season
    Breeding occurs between January and April, depending upon latitude.
  • Range number of offspring
    1 to 6
  • Average number of offspring
    3
  • Average number of offspring
    4
    AnAge
  • Range gestation period
    33 to 38 days
  • Average gestation period
    34.6 days
  • Range weaning age
    27 to 51 days
  • Average weaning age
    41.3 days
  • Range time to independence
    1 to 2 years
  • Average time to independence
    1 years
  • Range age at sexual or reproductive maturity (female)
    1 to 3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 3 years

Cynomys lodovicianus pups are altricial. They require a large investment by parents in order to ensure their survival. Males are not directly involved in caring for young, but help to protect pups within their coteries by defending the coterie against strange males. The bulk of parental care is provided by females, who nurse, groom, and protect their offspring. Because of the prevalance of infanticide in this species, young are very vulnerable prior to emergence from their natal burrows. After emergence from the burrow, however, young are less vulnerable. They eat solid foods primarily, although they continue to nurse for about one week. Interestingly, females in the coterie frequently nurse emergent pups other than their own offspring. (Hoogland, 1995; Hoogland, 1996)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • protecting
      • male
      • female
  • post-independence association with parents
  • inherits maternal/paternal territory

Lifespan/Longevity

As is true for most mammals, most black-tailed prairie dogs die young. Only 54% of females and 47% of males who emerge from their natal burrows survive their first year of life. Females can live to be up to eight years old, whereas males don't tend to live longer than 5 years under natural conditions. (Hoogland, 1995; Hoogland, 1996)

Behavior

Prairie dogs are the most social of the ground- dwelling sciurids. Prairie dog colonies, or towns, may contain hundreds of individuals living within a very restricted area. (The largest colony ever recorded occured in Texas. It covered an area of 65,000 km^2 and contained and estimated 400 million of animals.) Within the town there are certain neighborhoods, or coteries. Females typically remain in their natal coterie, whereas males disperse to a nearby coterie. Each coterie is populated by a group of closely related females (sister, mothers, aunts) and one or two territorial males. When multiple males are found in a single coterie, they are often brothers. Territories are defended aggressively from neighbors. (Hoffman, 1999; Hoogland, 1995)

Within the coterie, all things are shared most of the time. Burrow systems and food supplies are communal property. The only exception to this is during rearing of young, when females are aggressive toward one another and defend their burrows and nests from other prairie dogs. Territorial defense is usually shared by all members of the coterie. Male prairie dogs respond strongly to intrusions of other male prairie dogs, but seem oblivious to invading females. Female prairie dogs, by contrast, show the most aggression toward invading females. (Hoogland, 1995)

Praire dogs have long been noted for their highly social behavior. There is often playing, muzzling, mutal grooming, and a great deal of vocal communication. For instance, when a prairie dog spots a predator, such as a hawk, badger or black-footed ferret, it raises an alarm call, alerting its neighbors. All of the prairie dogs hearing this cry quickly scuttle into their burrows for protection.` (Hoogland, 1995; Hoogland, 1996)

The only time there is strife with a coterie is during the breeding season. Females display dominance relationships only when they are pregnant and lactating. During this time, females fight, and when they have the opportunity, they raid the burrows of other females and kill the pups they find there. It is not surprising that during this time, females aggressivley defend their natal burrow against other females. (Hoogland, 1995; Hoogland, 1996)

Once the young come above ground, however, harmony returns to the coterie. Indeed, young have been observed following the "wrong" mother into a burrow at night. The female nurses the youngster as if it were her own. It is not certain whether mothers can distinguish their young from the young of other mothers once the young have come above ground. (Hoogland, 1995; Hoogland, 1996)

Cynomys ludovicianus is diurnal and active throughout the year. Unlike many other species of prairie dogs, these animals do not hibernate. While they are active obove ground, observers might see them engaging in a variety of behavior, including moving dirt around to enhance burrow entrances, collecting nesting material, and scratching at fleas. (Hoogland, 1995)

As might be expected from the devotion of these animals to enhancing their burrows, the system of tunnels, nesting chambers, and mounds within a cology can be quite complex. They are used for protection from the elements, as well as from predators. Entrances are usually from 10 to 30 cm in diameter, although tunnels narrow a bit underground. Burrows measure an average of 5 to 10 m in length and 2 to 3 m in depth. However, burrows may be as long as 33 m amd as deep as 5 m. A coterie may have as many as 70 burrow entrances andcover 1/3 of a hectare. (Hoogland, 1995; Hoogland, 1996)

There are three types of entrances to a C. ludovicianus burrow. The most conspicuous type resembles a minature volcano, and has a high mound of dirt molded into a rim crater. Rim craters range in size from 1 to 1.5 m in diameter and can be as tall as 1 m. Rounded, unstructured mounds called dome craters may also be present. These are from 2 to 3 m in diameter, but are usually not taller than 0.3 m. The mounds of both types of craters allow individuals to see the surrounding territory to scan for predators. They also help prevent flooding in the burrow, and increase ventilation of the burrow. The burrows associated with both types af craters are apparently used for avoiding predators, spending the night, and rearing offspring. The final type of burrow entrance has no noticable mound at all. Such entrances to burrows are often found near the edge of the coterie territory. These burrows are apparently used only to escape predators and the heat of the day. They are not used at night or for rearing offspring. (Hoogland, 1995)

  • Average territory size
    333 m^2

Home Range

A coterie may cover 1/3 of a hectare. (Hoogland, 1995)

Communication and Perception

Communication within C. ludovicianus as been well studied. As might be expected from such a highly social species, means of communication are varied. Black-tailed prairie dogs have 12 distinct calls, including antipredator calls, and the conspicuous "jump-yip", in which an individual stretches to its full height on hind legs, then throws the forefeet into the air as it calls. The jump-yip call of one individual seems to excite other members of the coterie, as well as individuals in adjacent coteries, into producing their own "jump-yip" calls. (Hoogland, 1995; Hoogland, 1996)

In addition to vocal communication, C. ludovicianus employs physical contact (grooming, nuzzeling, playing, fighting), as well as visual signals for communication. Sniffing of other individuals occurs, and implies some chemical communication, especially in the context of mating. (Hoogland, 1995)

Food Habits

Black-tailed prairie dogs eat primarily leaves, stems, and roots of grasses, weeds, and forbs. Although vegetable matter comprises over 98% of the diet, animal matter may somteimes be ingested. The animals typically eaten by prairie dogs are grasshoppers, cutworms, bugs, and beetles. Black-tailed prairie dogs do not need to drink water in order to get the moisture they need to survive. They obtain all the moisture they need from their moist, leafy foods. Most prairie dogs forage close to their burrows when possible, moving into distant foraging areas only when forced to do so by local shortages of green shoots. (Hoogland, 1995; Hoogland, 1996)

Cynomys ludovicianus forages selectively from the plants available in its habitat. Diet also varies seasonally. In the summer, black-tailed prairie dogs prefer to feed upon wheatgrass (g. Agopyron), buffalo grass (g. Bromus), grama (g. Bouteloua), rabbitbush (g. Chrusothamnus), and scarlet globmallow. In the winter, they eat prickly pear cactus (g. Opuntia), thistles (g. Cirsium), and various roots. (Hoogland, 1995)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts
  • flowers

Predation

Black-tailed prairie dogs fall victim to a variety of predatory species. Terrestrial predators include coyotes, badgers, lynx, black-footed ferrets, rattlesnakes, and bullsnakes. Avian predators include prairie falcons, golden eagles, and a variety of hawks (Accipiter and Buteo). (Hoogland, 1995)

The greatest defense that C. ludovicianus has against predators is exactly the same thing which makes the species so vulnerable to predators; namely, the number of animals living together in a colony. Because there are so many prairie dogs in a single colony, colonies attract the notice of predators. But, because there are so many prairie dogs present, all scanning their environment periodically, predators are readily detected by these rodents. When a predator is noticed, individual prairie dogs give alarm calls, warning their relatives that danger is near. The prairie dogs can then take shelter immediately in one of the many burrows nearby. (Hoogland, 1995; Hoogland, 1996)

Ecosystem Roles

Black-tailed prairie dogs play a number of vital roles in their ecosystem. They modify the vegetational community, aerate the soil, provide food and shelter for a number of predators, and provide homes for a number of parasites. Each of these roles has extensive impact on the ecosystem. (Hoogland, 1995; Hoogland, 1996)

Prairie dogs modify the vegetational community in their habitat in two distinct ways. First, and most conspicuous, the vegetation found within prairie dog colonies is dramatically shorter than the vegetation in surrounding areas. Although C. ludovicianus appears to colonize areas where the vegetation is already short, they still actively modify the landscape after colonizing an area. The short vegetation results from a combination of foraging behavior and active trimming by these rodents. Shorter vegetation seems to benefit the prairie dogs by increasing visibility, and presumably, assisting in detection of predators. Second, through some mechanism as yet unknown, the prairie dogs facilitate the growth of certain plants within their communities. Some of these plants are only rarely found on the prairie outside of prairie dog towns. (Hoogland, 1995)

As a prey species, black-tailed prairie dogs provide food for other animals, including mammals, snakes, and birds of prey. Since they are primary consumers, they provide a vital link in food webs. (Hoogland, 1995; Hoogland, 1996; Nowak, 1999)

Of special note is the relationship between black-footed ferrets and C. ludovicianus. Black-footed ferrets are highly endangered mammals, the near extinction of which was intimately tied to their reliance on prairie dog colonies for food and shelter. Because of the large scale eradication of C. ludovicianus from rangelands, black-footed ferrets were unable to sustain an effective wild population. Although captive breeding of these ferrets has helped to restore the population, their continued survival depends on the availability of prairie dog colonies in which they can live. Some authors have suggested that predation by ferrets has set black-tailed prairie dogs apart from other species in the genus Cynomys, and may account for the higher levels of coloniality and sociality seen in this species. (Hoogland, 1995; Hoogland, 1995; Hoogland, 1995; Nowak, 1999)

One of the costs of coloniality that C. ludovicianus faces is a heightened level of parisitism. Black-tailed prairie dogs harbor numerous fleas, lice, and ticks. In addition to the discomfort that these parasites inflict, they infect the prairie dogs with diseases. For example, fleas transmit bubonic plague causing bacteria (Pasturella pestis). Plague, in addition to threatening the prairie dogs, can be transmitted to humans. (Hoogland, 1995; Nowak, 1999; Hoogland, 1995; Nowak, 1999; Hoogland, 1995; Nowak, 1999)

Economic Importance for Humans: Positive

Black-tailed prairie dogs are beneficial to humans in a variety of ways. They may help the vegetation in ways which benefit domestic cattle and horses. Because of their excavation of the soil and clipping of vegetation, as well as their fecal material and urine, many plants receive fertilization and optimal growing conditions. Bison, pronghorn antelope, and domestic livestock prefer for forage at the sites of prairie dog colonies when such are available. Beyond their utility in modifying the vegetation to the liking of livestock, black-tailed prairie dogs have been used in the laboratory for studies of gallstones. Prairie dog towns are popular among sightseers in the American west. In addition, prarie dogs are said to make excellent pets if captured young. Historically, these animals have provided food for native americans. (Hoffman, 1999; Hoogland, 1995; Hoogland, 1996)

Economic Importance for Humans: Negative

As is the case for their positive economic impact on humans, the negative impact of these animals on humans is varied. Cynomys ludovicianus has historically been considered a pest species, although most of the grounds for viewing it as such have been mistaken. Prairie dogs have been known to destroy crops of corn, wheat, alfalfa, hay, sorghum, potatoes and cantaloupes, causing some concern for agriculture. Although they are reported to compete with cattle and sheep for forage, there is actually little dietary overlap with these species. Cynomys ludovicianus burrow systems are alleged to present hazards to cattle and horses, making broken legs a threat. However, there are actually very few leg fractures in domestic livestock attributable to prairie dog burrows. Also, as discussed under "Economic Importance for Humans: Positive", the benefits of C. ludovicianus to the vegetational community may far outweigh the possible threat this species poses to agriculture. Prairie dogs may serve as a reservoir for spotted fever and bubonic plague. (Hoffman, 1999; Hoogland, 1995; Hoogland, 1996; Nowak, 1999)

  • Negative Impacts
  • injures humans
  • crop pest

Conservation Status

Historically, prairie dogs were villified by ranchers, and efforts were made to erradicate entire populations. Although not as common as they once were, many prairie dog colonies persist in protected areas. (Hoffman, 1999; Hoogland, 1996; Nowak, 1999)

Contributors

Nancy Shefferly (author, editor), Animal Diversity Web.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

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.

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.

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

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cooperative breeder

helpers provide assistance in raising young that are not their own

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

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

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).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

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.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polygynous

having more than one female as a mate at one time

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

social

associates with others of its species; forms social groups.

soil aeration

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

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

Hoffman, R. 1999. Black-tailed prairie dog (Cynomys ludovicianus). Pp. 445-447 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington, DC and London: The Smithsonian Institution Press.

Hoogland, J. 1995. The black-tailed prairie dog: Social life of a burrowing mammal. Chicago: Chicago University Press.

Hoogland, J. 1996. Cynomys ludovicianus. Mammalian Species, 535: 1-10.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

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