Cynomys ludovicianus (Arizona black-tailed prairie dog, Black-tailed Prairie Dog)

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Arizona Black-Tailed Prairie Dog habitats

This taxon can be found in the Colorado Plateau shrublands, as one of its North American ecoregions of occurrence. The Plateau is an elevated, northward-tilted saucer landform, characterized by its high elevation and arid to semi-arid climate. Known for the Grand Canyon, it exhibits dramatic topographic relief through the erosive action of high-gradient, swift-flowing rivers that have downcut and incised the plateau. Approximately 90 percent of the plateau is drained by the Colorado River and its tributaries, notably the lower catchment of the Green River.

A pinyon-juniper zone is extensive, dominated by a pygmy forest of Pinyon pine (Pinus edulis) and several species of juniper (Juniperus spp). Between the trees the ground is sparsely covered by grama, other grasses, herbs, and various shrubs, such as Big sagebrush (Artemisia tridentata) and Alder-leaf cercocarpus (Cercocarpus montanus).

A montane zone extends over large areas on the high plateaus and mountains, but is much smaller than the pinyon-juniper zone. The montane vegetation varies considerably, from Ponderosa pine in the south to Lodgepole pine and Aspen further north. Northern Arizona contains four distinct Douglas-fir habitat types. The lowest zone has arid grasslands but with many bare areas, as well as xeric shrubs and sagebrush. Several species of cacti and yucca are common at low elevations in the south.

Numerous mammalian species are found within the Colorado Plateau shrublands ecoregion, including the Black-tailed prairie dog (Cynomys ludovicianus); Long-eared chipmunk (Tamias quadrimaculatus); Utah prairie dog (Cynomys parvidens EN); Yellow-bellied marmot (Marmota flaviventris); and the Uinta chipmunk (Tamias umbrinus), a burrowing omnivore.

A large number of birds are seen in the ecoregion, with representative taxa: Chestnut-collared longspur (Calcarius ornatus NT); Greater sage grouse (Centrocercus urophasianus NT); Northern pygmy owl (Glaucidium gnoma); Cactus wren (Campylorhynchus brunneicapillus).

There are various snakes occurring within the Colorado Plateau, including: Black-necked garter snake (Thamnophis cyrtopsis), usually found in riparian zones; Plains Blackhead snake (Tantilla nigriceps); Black-tailed rattlesnake (Crotalus molossus), who seeks inactivity refuge in rock crevices, animal burrows and even woodrat houses. Other reptiles found here include the Common checkered whiptail (Cnemidophorus tesselatus).

There are only a limited number of anuran taxa on the Colorado Plateau; in fact, the comprehensive occcurrence list for the ecoregion is: Red-spotted toad (Anaxyrus punctatus); Canyon treefrog (Hyla arenicolor); Woodhouse's toad (Anaxyrus woodhousii); Couch's spadefoot toad (Scaphiopus couchii); Northern leopard frog (Lithobates pipiens); Plains spadefoot toad (Spea bombifrons); and Southwestern toad (Anaxyrus microscaphus). The Tiger salamander (Ambystoma tigrinum) is the sole salamander found on the Colorado Plateau shrublands.

The Colorado River fish fauna display distinctive adaptive radiations. The Humpback chub (Gila cypha), for example, is a highly specialized minnow that lives in the upper Colorado. It adapted to the water’s fast current and its extremes of temperature and flow rate. Dams and water diversion, however, have created a series of placid, stillwater lakes and side streams, and the Humpback chub may not be able to adapt to these altered conditions. The species, along with other native Colorado River fishes including the Bonytail (Gila elegans), Squawfish (Ptychocheilus lucius), and the Flannelmouth sucker (Catostomus latipinnis), may not survive much further in time.

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.

Range elevation: 1,300 to 2,000 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland

Comments: Habitat consists of dry, flat or gently sloping, open grasslands with low, relatively sparse vegetation, including areas overgrazed by cattle. The species occurs in open vacant lots at town edges in some areas. Young are born in underground burrows.

Habitat includes all major grassland types--short (Bonham and Lerwick 1976), mixed (Coppock et al. 1983), and tall (Osborn 1942); most abundant and an important community member in the Mixed Grass Prairie and Short Grass Plains associations (Carpenter 1940, in Osborn 1942). Tallgrass prairie habitat is mainly areas where wild or domestic ungulates or other disturbance has reduced the stature of the tallgrass; prairie dogs maintain the vegetation in a low stature (Osborn 1942, Koford 1958, Hubbard 1992).

Fine to medium textured soils are preferred (Merriam 1902, Thorp 1949, Koford 1958), presumably because burrows and other structures tend to retain their shape and strength better than in coarse, loose soils. However, sandy soils often support larger, coarser graminoids with lower forage quality; prairie dogs may avoid these forages and thus associated sandy areas (Wedin 1992). Colonies commonly are found on silty clay loams, sandy clay loams, and loams (Thorp 1949, Bonham and Lerwick 1976, Klatt and Hein 1978, Agnew et al. 1986). Encroachment into sands (e.g., loamy fine sand) occurs if the habitat is needed for colony expansion (Osborn 1942).

Shallow slopes of less than 10% are preferred (Koford 1958, Hillman et al. 1979, Dalsted et al. 1981), presumably in part because such areas drain well and are only slightly prone to flooding.

By colonizing areas with low vegetative stature, prairie dogs often select areas with past human (as well as animal) disturbance. In North Dakota and Montana, colonies tended to be associated with areas heavily used by cattle, such as water tanks and long-term supplemental feeding sites (Licht and Sanchez 1993).

See Clippinger (1989) for a habitat suitability index model.

More info for the terms: density, forbs, litter

Subterranean burrows created by black-tailed prairie dogs serve as refuges from the external environment and are one of the most important features of black-tailed prairie dog colonies. They are used for breeding, rearing young, and hiding from predators. Burrows are maintained from generation to generation and serve as stabilizers on the physical and social aspects of the colony [75]. Black-tailed prairie dog nests are located underground in burrows and are composed of fine, dried grass. Nest material is collected throughout the year by both sexes and all age classes [69,75]. Tunnel depth of black-tailed prairie dogs in central Oklahoma was typically 4 to 5 feet (50-60 inches) deep [144]. Most black-tailed prairie dog colonies contain 20 to 57 burrows/acre [20,75,81].

There are 3 types of burrow entrances- dome mounds, rimmed crater mounds, and entrances without structures around them. Entrance features may prevent flooding and/or aid in ventilation [69,75,81]. Dome mounds consist of loosely packed subterranean soil spread widely around the entrance of the burrow and tend to be vegetated by prostrate forbs. Rimmed crater mounds are cone-shaped mounds constructed of humus, litter, uprooted vegetation, and mineral soil. Black-tailed prairie dogs compact the soil of these mounds with their noses, creating poor sites for seedling establishment [23]. Rimmed crater mounds may be used as wallowing sites for American bison. Burrow entrances without structures around them are usually located on slopes >10% [75]. The density of black-tailed prairie dog burrow openings depends on both substrate and duration of occupation of an area [81].

Vegetation heights between 3 and 5 inches (7-13 cm) and a slope of 2% to 5% are optimal for detecting predators and facilitating communication amon black-tailed prairie dogs [25,27,37,75,81]. Grazing cattle keep vegetation short in the vicinity of black-tailed prairie dog colonies, reducing susceptibility to black-tailed prairie dog predators and potentially expanding colony size [59,75,81,89]. Black-tailed prairie dogs were rarely seen feeding >16 feet (5 m) from colony edges in Wind Cave National Park [50].

More info for the terms: cover, density, forbs, graminoid, litter, natural, shrubs, succession

Habitat preferences for the black-tailed prairie dog are influenced by vegetative cover type, slope, soil type, and amount of rainfall [111]. Black-tailed prairie dog foraging and burrowing activities influence environmental heterogeneity, hydrology, nutrient cycling, biodiversity, landscape architecture, and plant succession in grassland habitat [12,22,29,30,48,50,75,81,139,141,146].

Landscape-scale habitat characteristics: Black-tailed prairie dogs inhabit grasslands including short- and mixed-grass prairie, sagebrush steppe, and desert grasslands (see Plant Communities). Shortgrass prairies dominated by buffalo grass (Buchloe dactyloides), blue grama (Bouteloua gracilis), and western wheatgrass (Pascopyron smithii) [25,37,59,75,81], and mixed-grass prairies [12,23,25,28,36,45,50,71,99] that have been grazed by native and nonnative herbivores are preferred habitat [79,81]. Slopes of 2% to 5% and vegetation heights between 3 and 5 inches (7-13 cm) are optimal for detecting predators and facilitating communication [25,27,37,75,81].

In the Great Plains region, black-tailed prairie dog colonies commonly occur near rivers and creeks [81]. Of 86 black-tailed prairie dog colonies located in Mellette County, South Dakota, 30 were located on benches or terraces adjacent to a creek or floodplain, 30 occurred in rolling hills with a slope >5%, 20 were in flat areas, and 6 were in badland areas [64]. The slopes of playa lakes in the Texas panhandle and surrounding regions are used as habitat for the black-tailed prairie dog [108,109,110]. Black-tailed prairie dog colonies in Phillips County, Montana, were often associated with reservoirs, cattle salting grounds, and other areas affected by humans [111].

Black-tailed prairie dogs tolerate "high degrees" of disturbance over long periods of time [27,52]. New colonies are rarely created on rangeland that is in "good" to "excellent" condition; however, land that is continually heavily grazed for decades reduces habitat quality due to soil erosion [115]. Black-tailed prairie dogs may colonize heavily grazed sites but do not necessarily specialize in colonizing overgrazed areas. Overgrazing may occur subsequent to black-tailed prairie dog colonization [127]. Black-tailed prairie dogs were associated with areas intensively grazed by livestock and/or areas where topsoil had been disturbed by human activities in sagebrush-grassland habitat on the Charles M. Russell National Wildlife Refuge and Fort Belknap Indian Reservation in northeastern Montana. Roads and cattle trails were found in 150 of 154 black-tailed prairie dog colonies, and colonies were located significantly (P<0.001) closer to livestock water developments and homestead sites than randomly located points [79].

Site-scale habitat characteristics:
Vegetation: Plant community structure and species composition are impacted by black-tailed prairie dog colonization, and are related to the age of the colony and the level of expansion taking place [29,30,128]. Vegetation on black-tailed prairie dog colonies is typically of lower stature [50,75,81,146], and characterized by a higher percentage of bare ground, a higher cover of forbs and/or dwarf shrubs, and lower cover of grasses and larger woody plants than surrounding grassland [7,81,139]. As the black-tailed prairie dog colony ages, forbs and dwarf shrubs may dominate; younger colonies are dominated by grasses [29,141]. Black-tailed prairie dog colonies in Wind Cave National Park consisted of 3 vegetational zones. The interior zone was dominated by forbs, the edge zone was dominated by shortgrasses such as blue grama and buffalo grass, and the outer zone consisted of undisturbed mixed-grass prairie dominated by western wheatgrass, grama (Bouteloua spp.), and needlegrass (Stipa spp.) [50].

Shifts in vegetational structure and composition seem to occur about 10 or more years following initial colonization [23,29]. In a mixed-grass prairie in Badlands National Park, South Dakota, a  buffalo grass-dominated community remained relatively unchanged 4 to 7 years after a colony was established. When cover of shortgrass (primarily buffalo grass) fell below 75%, about 11 to 13 years after colonization, abrupt vegetational changes occurred. Forbs, armed and/or sprawling grasses, aromatic dicots, and bare ground dominated the area [23]. In Wind Cave National Park, changes in relative cover of graminoids, forbs, and dwarf shrubs occurred sometime between 8 and 26 years following black-tailed prairie dog colonization, while a decrease in litter and an increase in bare ground were detectable 1 to 2 years after colonization, as shown in following table [29]:

Ground cover (%) composition before (0 years) and during 26 years of black-tailed prairie dog colonization [29]

Age (years)

0

1 to 2

3 to 8

>26

graminoids 26 26 25 1
forbs and dwarf shrubs 10 7 11 29
total vegetation 36 33 36 30
litter 48 37 39 11
bare ground 16 30 25 59

Plant species diversity was greater on 2 large, rapidly expanding black-tailed prairie dog colonies compared to 2 small colonies with no room for expansion in mixed-grass prairie habitat in Billings County, North Dakota. The most common life form of plants on the 4 colonies was forbs; perennials outnumbered annuals and biennials combined. Graminoid diversity was greater on the large, rapidly expanding black-tailed prairie dog colonies. For a list of the 104 plant species identified, see Stockrahm and others [128].

According to Cid and others [22], the rate of vegetation change after the removal of grazing animals such as black-tailed prairie dogs is influenced by many factors, including grassland type, plant species composition, weather conditions, and prior intensity and duration of grazing [22]. Removal of black-tailed prairie dogs from a landscape by natural or anthropogenic factors could either release suppressed populations of woody plants or provide new habitat for woody plant colonization [4]. The removal of prairie dogs from northern mixed-grass prairies in Badlands National Park, South Dakota, did not result in rapid reestablishment of native vegetation. When seed banks were collected from black-tailed prairie dog colonies, few dominant species typical of mixed-grass prairie germinated in the laboratory compared to seed banks collected off of black-tailed prairie dog colonies. The authors suggested that unless the seed bank is restored, rapid reestablishment of representative mixed-grass prairie would be difficult [45]. In northeastern Colorado, vegetation changes following eradication of black-tailed prairie dogs were relatively minor and did not significantly (P-value not given) improve shortgrass prairie for use by cattle within 5 years. The following Table shows vegetation composition on 1 active and 3 abandoned black-tailed prairie dog colonies in a shortgrass prairie. Plant species in the table were listed only if they had >0.5% cover [77]:

Vegetation cover (%) on active and inactive black-tailed prairie dog colonies [77]

Vegetation Active colony 1 year abandoned 2 years abandoned 5 years abandoned
western wheatgrass 2.3 5.1 6.9 6.7
ring muhly (Muhlenbergia torreyi) 5.5 0.2 9.0 0.7
Indian ricegrass (Achnatherum hymenoides) ---- ---- ---- 0.6
purple threeawn 2.8 0.4 0.2 0.3
blue grama 20.7 22.8 9.8 22.2
buffalo grass 37.2 32.4 31.9 25.0
perennial grasses (subtotal) 68.5 60.8 57.7 55.2
annual grasses (2 species) ---- 0.1 ---- 0.5
forbs (14 species) 0.1 2.2 0.6 0.4
shrubs/half-shrubs (6 species) 2.1 2.7 1.9 2.0

Total vegetation cover (27 species)

70.7 65.5 60.3 58.3

Other habitat characteristics: Black-tailed prairie dog distribution is not limited by soil type, but by indirect effects of soil texture on moisture and vegetation. Black-tailed prairie dog colonies occur in many types of soil including deep, alluvial soils with medium to fine textures, and occasionally gravel. Soil that is not prone to collapsing or flooding is preferred [81]. Black-tailed prairie dogs do not select specific types of soil to dig burrows [75], but silty loam clay soils are best for tunnel construction [81]. Surface soil textures in black-tailed prairie dog colonies near Fort Collins, Colorado, varied from sandy loam to sandy clay loam in the top 6 inches (15 cm), with a sandy clay loam subsoil [11]. In northern latitudes, black-tailed prairie dog colonies commonly occur on south aspects due to the dominance of grasses over shrubs and increased solar radiation during winter. Burrows usually occur on slopes <10% [81].

Black-tailed prairie dogs mix the soil horizons by raising soil from deeper layers to the surface. This may significantly affect the texture and composition of soil at different layers. Feces, urine, and carcasses of black-tailed prairie dogs also affect soil characteristics [81].

Home range and population density: The home range and territorial boundaries of black-tailed prairie dogs are determined by the area occupied by an individual coterie. Coteries typically occupy about 1.0 acre (0.4 ha) [81].

Population density and growth are influenced by habitat quality [75,111] and are restricted by topographic barriers, soil structure, tall vegetation, and social conditions [75,81]. Urbanization and other types of human development may restrict colony size and spatial distribution [70]. Most plains habitats support at least 13 black-tailed prairie dogs/ha [81]. In a mixed-grass prairie at Wind Cave National Park, black-tailed prairie dog population densities were as follows [75]:

Black-tailed prairie dog density from 1948 to 1950 [75]
Sample date Area of black-tailed prairie dog ward (acres (ha)) Population
(no. of individuals)
Density
(no. of individuals per acre)
July 1948 5.2 (2.1) 44 8.5
July 1949 5.2 28 5.4
March 1950 5.2 21 4.0
May 1950 5.2 78 15.0
July 1950 7.3 (3.0) 82 11.2

Average

5.6 (2.3) 50 8.8

Mortality and emigration are major causes of population declines in black-tailed prairie dog colonies. The number of females >2 years old determines the total number of offspring each year [75]. Black-tailed prairie dogs have higher reproductive rates when the number of adults and yearlings in a population is low. A black-tailed prairie dog colony in Wind Cave National Park fluctuated from 92 to 216 individuals (mean (SD) =132.5 ± 29.3) on 16 acres (6.6 ha) over 14 years. The size of the physical area remained exactly the same over the time period [67].

Arizona Black-Tailed Prairie Dog size

Length: 42 cm

Weight: 1360 grams

Sexual Dimorphism: Males are larger than females.

Length:
Average: 387.8 mm males; 371.2 mm females
Range: 358-429 mm males; 340-400 mm females

Weight:
Average: 907g males; 863 g females
Range: 575-1,490 g males; 765-1,030 g females

Arizona Black-Tailed Prairie Dog distributions

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.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Arizona Black-Tailed Prairie Dog 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.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N2 - Imperiled

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Relatively large range in the plains region of central North America; many occurrences and large population size (millions), but extent of occupied habitat and abundance have been reduced from historical levels by about 98 percent; overall, threats are rated as moderate and not as serious as previsouly believed; long-term trend outlook is one of slow decline. The species appears to be secure but at a greatly reduced level.

Intrinsic Vulnerability: Moderately vulnerable

Comments: Reproduce slowly (for a rodent) and survivorship is low (see Ecology Comments), despite popular belief (Hoogland 2001).

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other Considerations: The Great Plains ecosystem evolved with bison, prairie dogs, and fire as major forces/processes; bison and fire are effectively gone, and the prairie dog is vastly reduced. The black-tailed prairie dog is a keystone species upon which many other prairie species depend, but now "may be as functionally extinct as the bison" (M. Gilpin, pers. comm. in Miller and Cully 2001). Black-footed ferret (MUSTELA NIGRIPES, G1) is almost completely dependent on prairie dogs for food. Mountain plover (CHARADRIUS MONTANUS, G2), burrowing owl (SPEOTYTO CUNICULARIA, G4), ferruginous hawk (BUTEO REGALIS, G4), and swift fox (VULPES VELOX, G3) are among those animals that are found in greatest numbers on prairie dog towns. The highly fragmented nature of the Great Plains makes dispersal and gene flow between populations problematic.

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