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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln

Great Plains Wildlife Damage Control Workshop Wildlife Damage Management, Internet Center Proceedings for

December 1993

The Dog and Endangered

Daniel W. Mulhern U.S. Fish and Wildlife Service, Manhattan,

Kenneth L. Powell U.S. Fish and Wildlife Service, Manhattan, Kansas

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Mulhern, Daniel W. and Powell, Kenneth L., "The Ecosystems and " (1993). Wildlife Damage Control Workshop Proceedings. 349. https://digitalcommons.unl.edu/gpwdcwp/349

This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Great Plains Wildlife Damage Control Workshop Proceedings by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. The Prairie Dog Ecosystems and Endangered Species

Daniel W. Mulhern Kenneth L. Powell U.S. Fish and Wildlife Service Manhattan, Kansas

The prairie dog is no doubt one of the most In one of the only controlled experiments controversial in the western United conducted to document the competitive States. Public sentiment regarding this effects of prairie dogs on , there were runs the gamut from some livestock slight reductions in weight gains of steers producers who are satisfied only with grazed on black-tailed prairie dog towns complete eradication of all prairie dogs, versus similar steers grazed on pastures and some rights groups who would with no prairie dogs (OMeilia et al. 1982). like to see all prairie dogs given complete While these reductions were not protection from any form of harm. Between statistically significant, they did result in these two extremes lie the real truths market values approximately $14-24 per surrounding this sometimes destructive, steer lower for the animals associated with mostly biologically beneficial, creature. this prairie dog species. This study occurred on pasture with a very high cattle stocking rate; the effects may have been The primary controversy involving prairie less with moderate stocking rate. No dogs, as is often the case with wild species, correlation has been made with the less lies in its tendency to conflict with the dense colonies formed by white-tailed or financial interests of humans. It is widely Gunnison's prairie dogs. believed that prairie dogs compete with There are also studies which have reported domestic livestock for valuable forage. the beneficial effects of prairie dogs on There is, in fact, considerable overlap in range condition, including increases in the diets of cattle and prairie dogs (Smith plant species diversity and richness in areas 1958), both grazers preferring grass over colonized by prairie dogs (Bonham and forbs. A single prairie dog may consume Lerwick 1976, Gold 1976, Archer et al. approximately 3 kg of vegetation per 1987). Prairie dog grazing produces higher month during the summer, and prairie dogs nitrogen concentrations in the shoots of also continuously clip taller vegetation newly growing vegetation which results within their colonies to remove visual from stems repeatedly being clipped off obstructions, with vegetation at the edges (Whicker and Deding 1988). In response to of the town thinned at least partially (King higher forage quality represented by these 1955, Koford 1958). The result of this tender new shoots, native grazers such as often is that grasses eventually become bison and preferentially select replaced by a higher percentage of forbs, prairie dog colonies over uncolonized sites particularly in the center of a colony. (Krueger 1986).

187 There are five recognized species of prairie , the black-footed ferret I, dog in , with four of these Mustela nigripes and the occurring in the U.S. (Figure 1). These Haliaeetus leucocephalus include the black-tailed prairie dog ( n m s ludovicianus), white-tailed prairie dog (.Q. The black-footed ferret has long been leucurus), Gunnison's prairie dog (_Q. i ni known to be closely associated with prairie , the federallylisted threatened prairie dogs, sheltering in their and dog feeding on prairie dogs and other small parvidens), and the federally-listed within a colony. Radiotelemetry endangered studies of black-footed ferrets show that mexicanus). Accurate reports of prairie dog they generally leave prairie dog colonies numbers or densities during presettlement only to travel to adjacent colonies, with do not exist, but it is estimated that in 1919 one individual ferret even avoiding an area there were approximately 40 million populated with ground (Biggins et hectares (99 million acres) of occupied al. 1985). Among the several factors prairie dog colonies in the U.S. (Nelson contributing to its decline, the reduction in 1919). Early naturalist Ernest Thompson prairie dog is cited as the principle Seton estimated that approximately 5 reason for the near extinction of the billion black-tailed prairie dogs occurred in black-footed ferret (U.S. Fish and Wildlife North America in the early 1900s (Foster Service 1988). Conversely, loss of prairie and Hygnstrom 1990). Control programs dog habitat is not cited as a factor in the and conversion of prairie to other land uses decline of the bald eagle, a species which is were estimated in 1978 to have reduced this typically associated with aquatic most widespread of prairie dog species to and feeds primarily on fish and waterfowl. less than two percent of its population However, observations by Fish acrd numbers of just a few decades before Wildlife Service personnel of wintering (Summers and Linder 1978). bald eagles in Colorado, and one nesting pair in Kansas, indicate that prairie dog The ecological significance of the prairie colonies can provide a significant source of dog is exemplified by the fact that various prey. Impacts to prairie dog colonies in surveys have reported from 64 to 107 particular areas may therefore potentially vertebrate species and subspecies identified affect local bald eagle populations. on prairie dog towns (Tyler 1968, Campbell and Clark 1981, Clark et al. 1982). What In addition to federally-listed species, a effect has the war on prairie dogs had on number of species which use prairie dog the natural ecosystem of which they are an colonies have declined suffciently for the integral part? How have other species Fish and Wildlife Service to have included which share this ecosystem fared during them in a list of federal candidate species this period? In addition to the two listed (Table 1). Category 1 candidate species are prairie dog species, there are at least two those species for which the Service has on species listed as endangered by the U.S. file substantial information on biological Fish and Wildlife Service which are known vulnerability and threats to support to utilize the prairie dog proposals to list them as

188 00 CD

1 = black-tailed prairie dog 2 3 = Gunnison's prairie dog 4 = white-tailed prairie dog =

Figure 1. Distribution of prairie dog species in the United States. endangered or . underground, the prairie dog burrows may Development and publication of proposed provide shelter for an individual or a rules to list category 1 species as family as well. So while swift foxes are threatened or endangered are anticipated at not completely dependent on prairie dogs some point in the future. Category 2 for sustenance, they are able to meet many candidates are species for which of their basic needs within a prairie dog information now in the possession of the colony. Service indicates that proposing to list as The eastern or plains spotted skunk is an endangered or threatened is possibly animal primarily associated with some appropriate, but for which conclusive data form of structure, such as brush or rock on biological vulnerability and threat are piles, and even abandoned buildings or not currenuy available to support proposed equipment. However, it is adapted to listing rules (U.S. Fish and Wildlife hunting on the open plains as well, Service 1991). searching for small and and The Utah prairie dog was nearly lost other invertebrates. It probably preys more because of prairie dog control programs, frequently on the smaller residents of a resulting in its listing as an endangered prairie dog colony, rather than the prairie species in June 1973. But under intense dogs themselves, but these skunks are management, it recovered to the point opportunistic and may eat young prairie where it could be downlisted to threatened dogs, or scavenge on carcasses of larger status in May 1984. With continued animals. management and protection, it may be possible to realize full recovery within five years (Robert Benton, U.S. Fish and There are four candidate mouse subspecies Wildlife Service, personal which occur in open in communication). Similar population losses Arizona, all of which may utilize the currently face the Arizona black-tailed prairie dog ecosystem to some extent. prairie dog, a category 2 subspecies. This Similarly, the kangaroo rat and the subspecies has been all but lost from Palo Duro mouse, in Texas, are believed to Arizona, primarily due to prairie dog occur at least occasionally in prairie dog control efforts in the state. colonies. Being primarily seed-eaters, they may each be susceptible to the placement The is one of the smallest canine of poison grain baits within a prairie dog predators in North America, occurring in colony. the short and mixed-grass of the The ferruginous is the largest of the Great Plains. This small fox feeds primarily buteos, or soaring , in North on small rodents, such as ground squirrels America, and the one most at home on the and prairie dogs, with other small wide open spaces of the Great Plains. It is vertebrates and invertebrates making up the the only buteo which has become adapted bulk of its diet Prairie dog towns offer a to successfully preying on prairie dogs for ready supply of food, both prairie dogs a significant portion of its diet. In certain themselves as well as the other small locations, pairs of ferruginous hawks may animals which find shelter in their be completely dependent on local prairie colonies. And since this fox dens dog populations for their food supply.

190 Larger birds of prey, such as bald and strychnine doses still lethal to birds two golden eagles, have been known to make a months following control measures for living by stealing prairie dogs and Richardson's ground squirrels. jackrabbits from ferruginous hawks, which The loggerhead shrike is a bird which are more adept at capturing the agile utilizes a variety of and shrubby rodents. habitats in the Great Plains. It usually requires at least some woody vegetation The , while technically a for nesting and shelter. However, it may shorebird, is actually a bird of shortgrass forage far into the open prairies in search prairies. Whether because of the shorter of insects and small rodents for food, and vegetation maintained by prairie dogs, or has been known to hunt in prairie dog because of the abundance of insects found colonies. in a prairie dog colony, these habitats are The Columbian sharp-tailed grouse is preferred by mountain plovers for nesting probably a casual visitor to prairie dogs areas. It is believed that, during the nesting when it does occur, as it utilizes a variety season, the mountain plover comes closer of short and mixed-grass habitats. It feeds than most other species to being a true on both insects and vegetation seeds, so prairie dog obligate; that is, it is dependent certain prairie dog control techniques on the prairie dogs and their ecosystem to could pose a risk to this species if it is support adequate nesting pairs. The decline present during or following control of the prairie dog in the Great Plains, measures. coupled with the tremendous development The Texas horned lizard is a small pressures on its southern wintering areas, of open grasslands, especially those with have contributed to the precipitous declines sandy soils. The Texas garter occurs of the mountain plover. in a variety of habitats, and has been The Baird's sparrow is also a bird of the recorded from within prairie dog colonies. Great Plains grasslands. It is not dependent They, too, do not necessarily seek out on prairie dog colonies as such, but prefers prairie dog colonies, but are no doubt short to mixed-grass prairies. Again, both attracted somewhat by the higher during migration and the nesting season, populations of invertebrates upon which the abundance of insects attracted to a they feed. prairie dog colony no doubt also attracts many individuals of several bird ' species, The regal fritillary butterfly is a showy including this grassland resident. Since this of various prairie habitat types, species also feeds at least in part on seeds, tending more toward mixed and tallgrass it may also be affected by poison grain prairie ecosystems. However, it is known baits. Apa et al. (1991 ), found adverse to occur within the range of the blacktailed impacts to another seed-eating bird, the prairie dog. It prefers prairies with a horned lark, from strychnine treated grain diversity of wildflowers, so changes in the used in blacktailed prairie dog colonies. vegetation of a prairie dog colony as a Further, Hegdal and Gatz (1977) reported result of control methods may at times have an effect on this species.

191 While not a candidate species, the golden more casual visitors to prairie dog eagle is a species of high public interest colonies may suffer less direct impacts, which also utilizes prairie dog colonies. although the specific control technique Unlike its more aquatic relative, the bald utilized in a given area may produce eagle, golden eagles are raptors of the significant effects as well. For example, Great Plains and mountains. They feed Baird's sparrows eat both insects and primarily on small mammals, including seeds, and may be susceptible to certain jackrabbits and prairie dogs. They both grain baits. capture their prey live, as well as feed on road-kills and other carrion. In areas where What the populations of many of these they are readily available, prairie dogs may species indicate is that there is a serious comprise a significant portion of a golden problem with the habitat which supports eagle's diet. them. For some, the prairie dog ecosystem is an integral, even critical, component of One other species of concern is the this habitat. Because of concern regarding . While it has not been the declines already noted, there has been included on the list of candidate species, it informal discussion among some Fish and has been identified through various survey Wildlife Service biologists about the results as a species in decline. It is also one possibility of designating one or more of of the most closely associated with prairie the unlisted remaining prairie dog species dog colonies of any bird species, as federal candidate species. As much as occupying prairie dog burrows for shelter 95 percent or more reductions in some and feeding on invertebrates within the prairie dog species no doubt qualifies them colonies. In many areas, populations of for such designation, if this were to be burrowing owls fluctuate depending on pursued. Such action would refocus whatever happens to the prairie dogs of the conservation attention to the core animal area. which itself creates habitat favorable to so many others. While this would in all At least three of the candidate species likelihood be a very controversial move, it discussed above, the swift fox, ferruginous may be biologically warranted, particularly hawk, and mountain plover, have received if trends do not change. serious consideration in recent years for potential inclusion on the list of threatened Because of land use changes, prairie dogs and endangered species. Of these, the today exist generally on poorer quality mountain plover appears to be most in range; they therefore are often blamed for need of some form of additional the condition of the prairie, when, in fact, protection, and may very well be included this is all that remains intact for them. In on the official list before too many years. the eastern part of prairie dog range, it is All three of these species, as well as the estimated that an overgrazed condition is and burrowing owl, are very more conducive for these rodents to closely tied to prairie dogs, and could be become established (Smith 1958). Even affected by changes in overall prairie dog where lethal control measures are applied acreages as well as adverse effects from to eliminate prairie dogs, it is possible for certain toxic control efforts. The other, them to rebuild to pre-treatment levels in as little as three years following

92 application, if other land use changes are Literature cited not enacted (Crosby and Graham 1986). In Apa, D.A., D.W. Uresk, and RL. Linder. fact, it is estimated that the maintenance 1991. Impacts of black-tailed prairie dog costs of typical control methods, poison rodenticides on nontarget passerines. Great grain baits and fumigants, may be greater Basin Nat. 51:301-309. than the annual value of the forage gained Archer, S., M.G. Garrett, and J.K. Detling. by these measures (Collins et al. 1984). 1987. Rates of vegetation change Therefore, it may be in the best interests of associated with prairie dog grazing in the livestock industry to take a second look North American mixed-grass prairie. at this basic program. Vegetatio 72:159-166. What is required is a change in attitude; a Biggins, D.E., M.H. Schroeder, S.C. change in the fundamental way land Forrest, and L. Richardson. 1985. managers, producers, and regulatory Movements and habitat relationships of agencies view prairie dogs and the radio-tagged black-footed ferrets. Pages ecosystem them sustain. While there are no 11.1-11.17 is Proc. Black-footed Ferret doubt situations where prairie dogs indeed Workshop, Sept. 18-19, 1984(S.H. warrant control to prevent undue range Anderson and D.B. Inkley, eds.). destruction, there needs to be a change Wyoming Game and Fish Dept., from the idea that control equates with Cheyenne, WY. 228 pp. eradication. It may be possible in some Bonham, C.D., and A. Lerwick. 1976. circumstances to reduce prairie dog Vegetation changes induced by prairie numbers and densities while maintaining or dogs on shortgrass range. J. Range even increasing overall acreages of prairie Manage. 29:221-225. dog colonies. If some measure of legal protection for the prairie dog ecosystem is Campbell, T.M., and T.W. Clark. 1981. to be rendered unnecessary, prairie dogs Colony characteristics and vertebrate need to be managed rather than eliminated. associates of white-tailed and black-tailed The public and private sector need to prairie dogs in Wyoming. Amer. Midl. Nat. demonstrate that they can cooperatively 105:269-276. manage a controversial species to serve the best interests of private landowners as well Clark, T.W., T.M. Campbell, D.G. Socha, as wildlife concerns. If this is not and D.E. Casey. 1982. Prairie dog colony accomplished, the number of federallylisted attributes and associated vertebrate species, with all the associated regulations species. Great Basin Nat. 42:572-582. and legal burdens, will only increase in the Great Plains. More importantly, if things do not change, this country will continue to see avoidable losses in its natural diversity.

Collins, A.R, J.P. Workman, and D.W. Uresek. 1984. An economic analysis of black-tailed prairie dog control. J. Range Manage. 37:358-361.

193 Crosby, L.A., and R Graham. 1986. O'Meilia, M.E., F.L. Knopf, and 1.C. Population dynamics and expansion rates Lewis. 1982. Some consequences of of black-tailed prairie dogs. Pages 112115 competition between prairie dogs and beef L Proc. 12th Vertebrate Conference, cattle. J. Range Manage. 35:580-585. Davis, CA. Smith, RE. 1958. Natural history of the Foster, N.S., and S.E. Hygnstrom. 1990. prairie dog in Kansas. Univ. Kansas Mus. Prairie dogs and their ecosystem. Univ. Nat. Hist., Misc. Publ. No. 49. 39 pp. Nebraska-Lincoln, Department of Summers, C.A., and RL. Linder. 1978. Forestry, Fisheries and Wildlife. 8 pp. Food habits of the black-tailed prairie dog Gold, I.K. 1976. Effects of black-tailed in western . J. Range prairie dog mounds on shortgrass Manage. 31:134-136. vegetation. M.S. Thesis, Colorado State Tyler, I.D. 1968. Distribution and Univ., Fort Collins, Co. 39 pp. vertebrate associates of the black-tailed Hegdal, P.L., and T.A. Gatz. 1977. Hazards prairie dog in . Ph.D. Thesis, to seed-eating birds and other wildlife Univ. Oklahoma, Norman, OK. 92 pp. associated with surface strychnine baiting U.S. Fish and Wildlife Service. 1988. for Richardson's ground squirrels. EPA Black-footed ferret recovery plan. U.S. Final Report, Interagency Agreement No. Fish and Wildlife Service, Denver, C0. 154 EPA-IAG-D4-0449. pp.

1991. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered King, J.A. 1955. Social behavior, social or threatened species, proposed rule. organization, and population dynamics in a Federal Register. 56(225):58804-58836. black-tailed prairie dog town in the Black Hills of South Dakota. Univ. Michigan Whicker, A.D., and J.K. Detling. 1988. Contrib. Lab. Vert. Biol. 67:1123. Ecological consequences of prairie dog disturbances. BioScience 38:778-785.

Koford, C.B. 1958. Prairie dogs, white faces, and blue grama. Wildl. Monogr. No. 3. 78 pp. Krueger, K. 1986. Feeding relationships among bison, pronghorn, and prairie dogs: an experimental analysis. 67:760-770.

Nelson, E.W. 1919. Annual report of chief, Bureau of Biological Survey. Pages 275 -298 in Annual Reports of the Department of Agriculture for the Year Ended June 30, 1919.

194 Table 1. Species designated as candidates for federal listing as endangered or threatened which utilize prairie dog ecosystems. Arizona black-tailed prairie dog n m ludovicianus arizonensis) Swift fox (Y u velox) Plains spotted skunk ( il Putorius interrupt Coconino Arizona pocket mouse I Perognathus amplus ammodytes Wupatki Arizona pocket mouse I perognathus ma P usl in Silky pocket mouse erognathus flavus good) Chiricahua western harvest mouse (Reithrodontomvs meealotis arizonensis) Texas kangaroo rat (Dipodomys elator) Palo Duro mouse (perom sy cus comanche Buteo LUAU) Mountain plover (Charge montanus) Baird's sparrow (Ammodramus bairdii Loggerhead shrike , anius ludovicianus) Columbian sharp-tailed grouse Tympanuchus phasianellus columbianus Texas horned lizard phrynosoma cornutum Texas Thamnophis sirtalis annectens Regal fritillary butterfly (speyeria id idalia

195