/ Prairie dogs (Cynomys spp.) have been labeled as keystone species because of their influence on biological diversity and ecosystem function. However, the validity of several assumptions used to support keystone status is questionable. We review the strength of the evidence and the magnitude of the prairie dog's effects on ecosystem structure and function. We use this review to reevaluate the keystone role for prairie dogs. Our goal is to encourage sound management of the prairie dog ecosystem by improving the ecological foundation of their keystone status. Our review confirms that prairie dogs affect a number of ecosystem-level functions but that their influence on prairie vertebrates may be less than previously suggested. Species richness and abundance patterns were variable among plants, mammals, and birds and were not consistently higher on prairie dog colonies compared to uncolonized areas. In addition, only nine of the 208 species listed in the literature as observed on or near prairie dogs colonies had quantitative evidence of dependence on prairie dogs. Abundance data indicated opportunistic use of colonies for an additional 20 species. A total of 117 species may have some relationship with prairie dogs, but we lacked sufficient data to evaluate the strength of this relationship. The remaining 62 species may be accidental or alien to the system. Despite our conclusion that some prairie dog functions may be smaller than previously assumed, collectively these functions are quite large compared to other herbivores in the system. We suggest that prairie dogs also provide some unique functions not duplicated by any other species and that continued decline of prairie dogs may lead to a substantial erosion of biological diversity and landscape heterogeneity across prairie and shrub-steppe landscapes. Thus, we concur that keystone status for prairie dogs is appropriate and may aid conservation efforts that help protect species dependent on prairie dogs and support other important ecosystem functions.KEY WORDS: Prairie dogs; Cynomys spp.; Keystone species; Ecosystem functions; Biological diversityhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n2p177.html

There exists considerable uncertainty whether differences between bison () and cattle (Bos taurus) should be exploited in natural area stewardship. Because foraging ecology may prescribe the fundamental relevance of either herbivore, we describe the foraging of bison and cattle on a northern mixed prairie natural area and discuss management implications. As generalist foragers, bison and cattle exhibited seasonal differences in selection for or against C"3 graminoids, C"4 grasses, forbs, and browse. Forty-eight hour in vitro dry matter digestibilities of C"3 graminoids and C"4 grasses were greater by bison than cattle, but equal digestive efficiencies were exhibited for forbs and browse. Dietary in vitro dry matter digestibility and crude protein differed little between herbivores. Cattle allocated more time to grazing than bison did during summer. Our study suggests that the relationship between feeding-time investment and forage patchiness is important in determining differences in diet choice between bison and cattle. In contrast to cattle, it appears that bison balance nutrient and time demands during the rut by consuming almost exclusively graminoids. Apparently, bison and cattle may achieve similar dietary quality through different foraging behavior. We suggest that specific scale-dependent programmatic conditions exist where either herbivore may be the most appropriate for natural area management.

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The sagebrush-grass rrnge in southcentral Wyoming presently summer and winter grazing seasons of 198 I. supports large numbers of feral homes and domestic livestock. Diets of feral horses and cattle during summer and winter grazing Study Area were evaluated using fecal analydr under 2 stocking levels in small pastures. Horses and cattle consumed primarily grasses during the Study sites were located in the Red Desert, northeast of Rock summer and winter. However, shrubs and forbs were also impor-Springs, Wyo., in Sweetwater County(Fig. I). A semiarid climatic tant dietary components. Needleandthread, Sandberg bluegrass, thickspike wheatgrass, Indian ricegrass, gray horsebrush, and winterfat were the maJor foods of horses and cattle during the summer anti wfnter. Dietary overlap between horses and cattle during the summer averaged 72% and Increased to 84% during the winter. Horses and cattle selected foods in a simllrr order. Large increases in feral horse (Equus cubaflus) numbers have occurred in the western United States since passage of the Wild Free-Roaming Horse and Burro Act of 1971 (Artz 1977, Wolfe 1980). These increases have become a major concern to public land managers, livestock producers, and animal welfare groups. Cook (1975) reported a 20-30% annual increase in feral horse populations in the western United States yearly from 1973 through 1975. This increase in population has forced public land administration agencies to reduce domestic livestock grazing in localized areas to accommodate the grazing pressure feral horses have added on Fig. 1. Locations ofsummer and winrer sites in the Wyoming Red Lksert. western ranges (Artz 1977). In 1974 the feral horse population in pattern prevails over both areas. Yearly precipitation averages 21.5 Wyoming was estimated at 4,434 animals; however a recently cm with approximately 40% falling from April to June. Snowfall completed census estimates the population at 10,448 animals usually occurs from October to May (BLM 1978 a,b). (USDI-BLM and USDA-FS 1980). Three distinct vegetation types cover most of the summer study An important factor in determining proper animal stocking area. The sagebrush-grass type on sandy and loamy range sites is levels for a given range is the botanical composition of diets of characterized by a shrub layer of big sagebrush (Artemisia tridenmajor herbivores and the relationship of diets to available forages. tata subsp. tridentata, vaseyanu, Wyomingensis), Douglas rabbit-Animal Science, University of Wyoming, assistant professor, Division of Range greasewood (Sarcobatus vermiculatus), rubber rabbitbrush (Chrymanagement, an! associate profeso~, Division of Animal Science, University of sothamnus nauseosus), fourwing saltbush (Atriplex canescens), Wypming, Laranue 8207 I. Mr. Krysl IS currently a graduate assistant! Department of ;;&?I and Range Scwnces. Box 3-1. New Mexxo State Universl(y, Las Cruces spiny hopsage (Grayia spinosa), Sandberg bluegrass, Indian ricegrass, needleandthread, lambsquarter (Chenopodium alba), west-This study was ...

During the first half of the twentieth century, widespread regulatory efforts to control cattle brucellosis due to Brucella abortus in the Union of Soviet Socialist Republics were essentially non-existent, and control was limited to selective test and slaughter of serologic agglutination reactors. By the 1950s, 2-3 million cattle were being vaccinated annually with the strain 19 vaccine, but because this vaccine induced strong, long-term titers on agglutination tests that interfered with identification of cattle infected with field strains of B. abortus, its use in cattle was discontinued in 1970. Soviet scientists then began a comprehensive program of research to identify vaccines with high immunogenicity, weak responses on agglutination tests and low pathogenicity in humans, as a foundation for widespread control of cattle brucellosis. While several new vaccines that induced weak or no responses on serologic agglutination tests were identified by experiments in guinea pigs and cattle, a large body of experimental and field studies suggested that the smooth-rough strain SR82 vaccine combined the desired weak agglutination test responses with comparatively higher efficacy against brucellosis. In 1974, prior to widespread use of strain SR82 vaccine, over 5300 cattle farms across the Russian Federation were known to be infected with B. abortus. By January 2008, only 68 cattle farms in 18 regions were known to be infected with B. abortus, and strain SR82 continues to be the most widely and successfully used vaccine in many regions of the Russian Federation.

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