Picture from: http://www.dnr.state.co.us./wildlife/T&E/btprairiedog.htm
BLACK-TAILED PRAIRIE DOGS
IDENTIFICATION
The scientific name for the black-tailed prairie dog "ludovicianus", is the Latin form of Ludwig or Louis, relating back to the Lewis and Clark expedition of 1804-1806, when prairie dogs were first collected for science. The prairie dog is a burrowing member of the order Rodentia, the largest group of mammals in world. The adult black-tailed prairie dog (Cynomys ludovicianus) is between 12 and 17 inches long and generally weighs between 1.5 and 3.0 pounds. Its tail is covered with hair and is about one-fourth of the animal’s total length. Its body is yellowish tan to pale brown in color, its belly is slightly lighter in color, almost a buffy white, and its tail is tipped with black. Their head is broad and rounded and their eyes are somewhat large for their body size. They have short ears, a short tail, and short legs, but their feet are large and have well-developed claws, especially on the forefeet.
BREEDING AND REPRODUCTION
A prairie dog reaches sexual maturity after its first winter and has one litter per year. Breeding takes place in March and early April, and a litter of usually four to six young is born 30 to 35 days later. Young prairie dogs are born hairless, helpless, and with their eyes closed. They remain underground for about six weeks and first emerge from the den in May or June. They are weaned at this time and begin feeding on green vegetation. They reach adult size by fall and usually live 3 to 5 years. One female prairie dog can produce from 3 to 20 young in her lifetime.
FEEDING
Grasses are the preferred food of the prairie dog, and generally makes up about three-quarters of its diet. In the fall, broadleaf forbs become moreimportant as green grass is less available. In winter, any available green vegetation is consumed. In the spring and summer, each prairie dog consumes up to two pounds of vegetation per week.
In addition to the vegetation it eats, the prairie dog also clips, but does not eat, much vegetation within its colony. This is probably done to keep the vegetation clipped short to provide an unobstructed view of approaching predators. Over a period of time, clipping, oraging and digging activities can alter the composition of the vegetation in a prairie dog town. Short native grasses like buffalograss and the grama grasses are favored when an area is used by prairie dogs for a long period of time.
HABITAT AND HOME
Areas of short and mid-grass rangeland overgrazed by livestock are the prairie dog's preferred habitat. Prairie dog colonies are most recognizableby the mounds and holes at their burrow entrances. A colony will typically have 30 to 50 burrow entrances per acre. The animal's burrow system can be quite complex and extensive. Mounds of excavated soil around the burrow entrance are generally cone-shaped and vary from one to three feet in height and from 3 to 10 feet in diameter. These mounds serve as lookout points and serve to prevent water from entering the burrow system. Tunnels are generally three to six feet below the surface and about 15 feet long, although burrows have been reported to reach depths of 15 feet. Burrow systems typically include several chambers, including one near the entrance where the prairie dog can sit and listen for activity above ground, and one or more nest chambers where they sleep and care for their young.
HABITS
Five species of prairie dogs in North America (Utah, Gunnison, White- tailed, Mexican, and Black-tailed) live in colonies. However, the black-tailed prairie dogs live in contiguous, territorial family groups called coteries.
The fact that the black-tailed prairie dogs live in colonies indicates they are highly social animals. The largest social unit is the colony or town. Towns are often divided into "wards" by topographical barriers such as roads, ridges or trees, and are generally five to 10 acres in size. Although prairie dogs in one ward may be able to see and hear animals of an adjacent ward, movement among wards is unusual. Wards are divided into several smaller prairie dog social units, called "coteries." Each coterie generally consists of one adult male, one to four adult females, and any offspring less than two years old. Members of one coterie defend their territory from invasion by members of other coteries.
Prairie dogs are active during the day; usually from about sunrise to sunset, and during the summer they spend about one-third to one-half of the daylight hours feeding. Another third is involved in social interactions with other colony members as well as working on burrows and mounds and responding to alarm calls. The remainder of daylight is spent underground, especially during mid-day when temperatures above ground are high.
The black-tailed prairie dog is active all year. In winter, it remains underground for several days when weather is severe, but comes out on sunny afternoons to look for food and bask in the sun.
Black-tailed prairie dogs exhibit an elaborate communication system. At least 11 separate calls have been identified, and a variety of postures and displays are utilized. Calls range from signals of alarm to "all-clear." Physical contact is another method of prairie dog communication. Mouth-to-mouth contact is used to identify coterie members from strangers, and grooming among coterie members is common.
RANGE
Black-tailed prairie dogs are found east of the Rocky Mountains in the states of Montana, Wyoming, South Dakota, North Dakota, Oklahoma, Texas, New Mexico, Colorado, Kansas, and Nebraska. They are also found in the southern part of Canada and the northern part of Mexico. Small colonies of black-tailed prairie dogs are still intermittently distributed throughout most of this range. But presently, there are only seven relatively large black-tailed prairie dog complexes remaining in North America (each more than 10,000 acres). Collectively these seven colonies comprise an estimated 36% of all occupied black-tailed prairie dog habitats in North America. Three of these large colonies live on tribal lands in South Dakota managed by the Cheynne Rive Sioux, the Rosebud Sioux, and the Ogala Sioux Pine Ridge Indian Reservation. The other four are on Buffalo Gap National Grasslands in South Dakota and Thunder Basin in Wyoming, both managed by the Forest Service/USDA, Fort Belknap Indian Reservation in Montana and on private land in Mexico.
Most of the other 64% of the habitat in North America, occupied by black-tailed prairie dogs are made up of isolated towns of less than 100 acres in size. The isolation of colonies makes it very difficult for the species to repopulate areas affected by disease or natural catastrophes. Small, isolated colonies may be more vulnerable to threats and less likely to survive over the long- term. Also, mature individual prairie dogs may disperse from the home colony and move about 2-1/2 miles usually into an already establishedcolony rather than attempting to start a new colony. Therefore, prairie dog towns isolated from other towns by great distances will not mix. This lack of interchange may affect long-term survival of the species. When movement between colonies is limited, there is an increased likelihood of genetic inbreeding and a decreased likelihood of repopulation following declines.
PUBLIC PERCEPTION AND ATTITUDES
BENEFITS
Prairie dogs are an integral part of the prairie grassland ecosystem and their presence increases both animal and plant diversity. The black-tailed prairie dog provides important habitat for and is prey for many species. The endangered black-footed ferret, mountain plover, burrowing owl, swift fox, badger, and ferruginous hawk are often found using black-tailed prairie dog habitat. Burrowing and grazing activities of prairie dogs affect many ecosystem functions and processes, including vegetation structure, plant composition, nutrients available in soil for plants, soil turnover, soil chemistry, energy flows, nutrient quality of plants, and plant succulence.
Prairie dog grazing maintains plants in an early vegetative state, and thus more nutritious state, by preventing the roughness and decline in nutrition, which normally develops as plants age. The rapid plant growth and recycling of energy that comes with constant clipping also encourages the amount and diversity of vegetation. In addition to the numerous small prey species that are attracted to prairie dog towns because of the diverse vegetation, grazers such as bison, pronghorn, deer, and elk all benefit from the especially nutritious perennial grasses and forbs.
Studies have found that prairie dog towns host more species than do adjoining grasslands without prairie dogs. Many species thrive on the abundant food supply found in the towns. Deer mice and rabbits thrive on the nutritious plants. Toads, salamanders and lizards all prey on one or more of the insects, worms, and spiders living on prairie dog towns. Rattlesnakes and bullsnakes feed on mice, rabbits and even prairie dogs themselves. Black-footed ferrets, coyotes, swift foxes, badgers, ferruginous hawks and golden eagles all feed on prairie dogs. Meadowlarks, grasshopper sparrows, and other birds are found in prairie dog towns because they are attracted to the open spaces, where seed and insects are more accessible. Also, cottontail rabbits, several species of small rodents, burrowing owls, and snakes use vacant burrows as their homes.
PUBLIC PERCEPTION AND THE TRUTH
Perception:
Prairie dogs are everywhere.
The Truth:
Black-tailed prairie dogs historically covered between 10 and 20 percent of the Great Plains. Today, they occupy less than one percent of their historic area. Even on our public grasslands, prairie dogs occupy only 2 percent of the landscape. For example, they occupy only 2 percent of the Badlands National Park, 1.3 percent of the Buffalo Gap National Grassland, and 0.4 percent of the Pawnee National Grassland here in Colorado.
Perception:
Prairie dogs destroy grasslands and cause erosion.
The Truth:
Prairie dogs actually maintain open grasslands in some regions by preventing shrubs, such as sagebrush and mesquite, from growing in these areas. Prairie dogs also can decrease erosion. Through burrowing and digging on the surface for roots, prairie dogs loosen the soil and allow rainwater to percolate more efficiently. Comparisons of prairie dog towns without livestock grazing and prairie dog towns with livestock grazing show that the prairie dog towns without livestock grazing sustain healthy soil conditions, while the towns with livestock grazing exhibit more erosion and bare surface area, and less plant productivity.
Perception:
Prairie dogs hurt livestock operations by eating all available grass.
The Truth:
Prairie dogs do reduce the height and amount of vegetation on their towns, but the mere appearance of the grass does not tell the whole story. The vegetation on prairie dog towns often has greater nutritional value than vegetation in other areas. Prairie dogs are constantly clipping vegetation, which causes dead matter to be removed. The clipped vegetation also remains in a state of regrowth for a longer season than surrounding unclipped vegetation. Some studies have found that cattle grazed in pastures occupied by black-tailed prairie dogs had no significant differences in weight gain compared to cattle grazed in pastures without prairie dogs. On the other hand, drought and overgrazing may heighten competition for forage (whether consumed or clipped) between the species; these factors also encourage expansion of prairie dog colonies into new areas. Conversely, lush vegetation in wet years may mask competition between the species and restrict prairie dog expansion where dense vegetation acts as a barrier. These relationships are complex and not fully understood. Interpreting the economic impact that prairie dogs have on livestock production depends on many things, including the specific site, weather patterns, time of year and various other factors.
PLAGUE, BLACK-TAILED PRAIRIE DOGS, AND HUMANS
Plague is an infectious disease caused by the bacterium, Yersinia pestis. All forms of plague in wild animals are generally referred to as sylvatic plague. Plague was inadvertently introduced from Asia into the North American prairie ecosystem around 1900. It is now found in 76 species of mammals, but it is primarily a disease of wild rodents other than black-tailed prairie dogs.
Plague has had a direct negative effect on the black-tailed prairie dog. This disease may be the most important factor in the recent reduction of black-tailed prairie dog populations across their range. In black-tailed prairie dogs, the plague was first documented in a colony near Lubbock, Texas, in 1946. Plague has been active in black-tailed prairie dog populations in the northern Great Plains only within the last decade although it was present 40-50 years ago. The disease appears to be spreading to encompass the entire range of the species. Plague is not widespread throughout the west because of the prairie dog. The disease is maintained in other wildlife species and periodically devastates black-tailed prairie dog populations; recent population losses due to plague have been observed in Montana, Wyoming, Colorado, Kansas, Nebraska, North Dakota, Texas, Arizona, and Oklahoma.
At present, sylvatic plague is widespread throughout the western United States, except in South Dakota. It is likely no coincidence that 4 of the largest 7 remaining black-tailed prairie dog complexes are in South Dakota or that approximately 32 percent of all remaining individuals of the species are located in this state. Black-tailed prairie dog populations are extinct in Arizona and are much reduced in the southwestern states (New Mexico, Colorado, and Utah) near the epicenter for more recent sylvatic plague outbreaks.
A plague outbreak in a black-tailed prairie dog colony results in near 100 percent mortality. Black-tailed prairie dogs show neither effective antibodies nor immunity. If there are any survivors, they do not exhibit resistance to plague; surviving animals appear to have avoided death only by the remote chance of avoiding exposure. Although the populations often grow in size after an outbreak, current information suggests they do not reach former levels.
In cases where people have contracted plague, it is usually referred to as bubonic plague. When people contract the disease, it is usually from coming in contact with an infected rodent or their fleas. But, plague can also be transmitted between humans or animals by direct contact (coughing, sneezing, etc.) Dogs are mostly immune to the plague. Cats are extremely susceptible to plague, although the occurrence of plague in cats is very rare. Although extremely rare, cats can pass the disease directly to people. Awareness of the disease and avoidance of close contact with wild rodents and other potential carriers or their fleas is the key to protection.
Though most prairie dogs have fleas, few fleas are infected, and most public health officials believe the chance of humans contracting plague from prairie dog fleas is very low. Apparently, prairie dog fleas do not like human hosts, preferring instead to bite other animal species. Health officials say the biggest risk is in people allowing their pets to run free in the area of prairie dog colonies or other wild rodents. If the fleas are brought into homes, there is an increased risk of the disease spreading to humans. Health officials offer the following tips to avoid plague:
Keep pets on a leash or leave them at home.
Wash pets with shampoo and treat with a flea powder.
Avoid areas where there are rodents.
Use insect repellent on exposed skin.
