Prairie Dog Colonies Research Articles

Trophic Transfer of Fipronil Residues to Black-footed Ferrets: Implications for Flea Control and Plague Mitigation

Abstract Sylvatic plague, caused by the flea-borne bacterium Yersinia pestis, is an invasive disease in North America that causes reductions of native fauna and transforms ecosystems. Fipronil baits have shown promise in reducing flea loads on prairie dogs Cynomys spp. for plague mitigation. Many species depend on prairie dogs and their ecological influences, including the black-footed ferret Mustela nigripes (ferret), an obligate predator of prairie dogs. To better understand how fipronil affects ferrets, we offered carcass portions from black-tailed prairie dogs C. ludovicianus that had consumed fipronil bait (0.005% fipronil by weight) to captive ferrets and monitored their health. We fed carcass portions of three prairie dogs to four adult ferrets for 1 week. No ill effects were observed in the ferrets. We collected scat from the ferrets before, during, and after their feeding on treated prairie dogs. We evaluated potential effects of ferret scat on larval fleas, which feed on organic matter. Fipronil residues were not detected in ferret scat samples collected before treatment. During and shortly after treatment, ferret scat contained 3.76 ng/g fipronil and 13.75 ng/g fipronil sulfone, on average, demonstrating trophic transfer of the residues from prey to predator. We presented 0.5 mg of ferret scat to each of 96 larval Oropsylla montana (Siphonaptera: Ceratophyllidae) and assessed survival rates over 24 h. When exposed to ferret scat lacking fipronil residues, 85% of larvae survived. Survival was reduced to 61% and 35% for larvae contacting or consuming scat with fipronil-residue, respectively. Fipronil residues in scat from a variety of species on prairie dog colonies, perhaps especially the prairie dogs, may assist in flea control and plague mitigation. Hosts eliminate fipronil residues, and fipronil residues in the environment degrade over time, reducing but not eliminating potential concerns with bioaccumulation.

Coyote use of prairie dog colonies is most frequent in areas used by American badgers.

The consequences of intraguild predation on vulnerable subordinate species are an important consideration in the recovery of endangered species. In prairie ecosystems, coyotes (Canis latrans) are the primary predator of endangered black-footed ferrets (Mustela nigripes; hereafter, ferrets) and presumably compete for prairie dog (Cynomys spp.) prey. Coyote predation of ferrets is thought to occur at night when ferrets are active aboveground; however, the apparent source of competition, diurnal prairie dogs, are belowground and inaccessible to coyotes at this time, presenting a perplexing temporal mismatch between actual and expected times that coyotes and ferrets come into conflict. Our study used remote wildlife cameras, occupancy models, and overlap of circadian activity patterns to investigate how landscape features, prairie dog colony attributes, and attraction to sympatric species, i.e., American badgers (Taxidea taxus; hereafter, badgers) and lagomorphs (cottontail rabbits and jackrabbits) influence Coyote use of prairie dog colonies and potential Coyote-ferret interactions. We first evaluated Coyote use (i.e., occupancy) between prairie dog colonies and surrounding available grasslands, finding that coyotes whose home ranges include prairie dog colonies used colonies nearly twice as much as surrounding grasslands. Next, we investigated biotic and abiotic factors that may influence Coyote use and frequency of use (i.e., detection probability) on prairie dog colonies. We found high Coyote use across all areas on prairie dog colonies; however, their frequency of use increased in areas that were also used by badgers. High overlap between Coyote and badger activity patterns (81%) further supports the spatial use patterns revealed by our occupancy analysis, and badgers and coyotes are known to form hunting associations. Interspecific competition and overlapping patterns of resource use between badgers and ferrets have been documented in previous studies; our study supports these findings and suggests that Coyote attraction to badger activity may influence Coyote-ferret interactions.

Overwintering Raptor Abundance and Community Composition in Relation to Prairie Dog Colonies in the Southern and Central Great Plains

Overwintering Raptor Abundance and Community Composition in Relation to Prairie Dog Colonies in the Southern and Central Great Plains

Toward broad-scale mapping and characterization of prairie dog colonies from airborne imagery using deep learning

Monitoring wildlife is fundamental to managing the health of rangelands but challenging due to the extensive and dynamic nature of these ecosystems. The black-tailed prairie dog (Cynomys ludovicianus) is considered both a keystone species of conservation concern and an agricultural pest. This animal is an example of a wildlife species for which detailed monitoring is both high priority and difficult to accomplish cost-effectively using ground-based methods. In this study, we conducted a robust evaluation of the potential to use deep learning to detect prairie dog burrows from remotely sensed imagery acquired from unoccupied aerial systems (UAS). We processed UAS imagery to create RGB, topographic position index (TPI) and normalized difference vegetation index (NDVI) products at varying spatial resolutions (2–30 cm). We then evaluated the minimum set of inputs and image resolution required to train a deep convolutional neural network (CNN) for burrow detection and scale this up to identify entire colonies. We validated results at the scale of individual burrows, sub-colony burrow density and range-wide colony area using ground and digitized observations. We found the 2 cm imagery proved computationally impractical for scaling, but performance did not decline between 2 and 5 cm imagery, and models performed well up to 10–15 cm. The top models always included TPI and the combination of RGB + TPI tended to perform best across spatial resolutions. Adding NDVI generally did not improve model performance. At 5 cm resolution, the top models achieved high precision and recall for detecting individual burrows (F-score 0.84–0.87) and burrow density was strongly correlated with validation data (r = 0.94–0.95). In pastures with active colonies, overlap between predicted and ground delineated colonies was high (60–94%). The CNN-based approach could not distinguish between currently active colonies and a colony that had recently become inactive due to a sylvatic plague (Yersinia pestis) epizootic. However, further analysis showed that CNN-derived burrow density was related to colony age and satellite-derived vegetation conditions in active colonies, and that the plague-affected colony deviated from expected vegetation trends. We conclude that a deep learning algorithm can accurately detect prairie dog burrows from UAS imagery acquired at 5–10 cm resolution, and that scaling from individual burrows to entire colonies is achievable but warrants further research. Combining CNN-derived burrow density maps with satellite-derived vegetation conditions may help identify recent colony abandonment, despite ongoing presence of burrows.

Fine-scale spatial variation shape fecal microbiome diversity and composition in black-tailed prairie dogs (Cynomys ludovicianus)

BackgroundHost associated gut microbiota are important in understanding the coevolution of host-microbe, and how they may help wildlife populations to adapt to rapid environmental changes. Mammalian gut microbiota composition and diversity may be affected by a variety of factors including geographic variation, seasonal variation in diet, habitat disturbance, environmental conditions, age, and sex. However, there have been few studies that examined how ecological and environmental factors influence gut microbiota composition in animals' natural environments. In this study, we explore how host habitat, geographical location and environmental factors affect the fecal microbiota of Cynomys ludovicianus at a small spatial scale. We collected fecal samples from five geographically distinct locations in the Texas Panhandle classified as urban and rural areas and analyzed them using high throughput 16S rRNA gene amplicon sequencing.ResultsThe results showed that microbiota of these fecal samples was largely dominated by the phylum Bacteroidetes. Fecal microbiome diversity and composition differed significantly across sampling sites and habitats. Prairie dogs inhabiting urban areas showed reduced fecal diversity due to more homogenous environment and, likely, anthropogenic disturbance. Urban prairie dog colonies displayed greater phylogenetic variation among replicates than those in rural habitats. Differentially abundant analysis revealed that bacterial species pathogenic to humans and animals were highly abundant in urban areas which indicates that host health and fitness might be negatively affected. Random forest models identified Alistipes shahii as the important species driving the changes in fecal microbiome composition. Despite the effects of habitat and geographic location of host, we found a strong correlation with environmental factors and that- average maximum temperature was the best predictor of prairie dog fecal microbial diversity.ConclusionsOur findings suggest that reduction in alpha diversity in conjunction with greater dispersion in beta diversity could be indicative of declining host health in urban areas; this information may, in turn, help determine future conservation efforts. Moreover, several bacterial species pathogenic to humans and other animals were enriched in prairie dog colonies near urban areas, which may in turn adversely affect host phenotype and fitness.

A low‐pressure compressed air insecticide applicator to manage plague on prairie dog colonies using all‐terrain vehicles

AbstractVector control is an important tool for plague management in native wildlife such as prairie dogs (Cynomys spp.) and black‐footed ferrets (Mustela nigripes). Given the success of previous prototype high‐pressure air (HPA) dusters, we developed a low‐pressure air (LPA) duster that can be mounted on and powered via all‐terrain vehicle (ATV). We describe the duster prototype and compare performance to commercially available dusters and previous high‐pressure air dusters. In 2021, we infused 0.05% deltamethrin (dust) into black‐tailed prairie dogs burrows (C. ludovicianus) in Larimer County, Colorado. We then captured prairie dogs and compared flea abundance and prevalence on a site dusted with prototype LPA dusters to a non‐dusted site. The mean amount of dust (g) dispensed per burrow was higher using the LPA duster ( = 6.37, 95% CI = 6.24–6.50) from ATVs when compared to HPA prototypes ( = 5.39, 95% CI = 5.27–5.52, P ≤ 0.01) and the commercial dusters used previously ( = 5.29, 95% CI = 5.05–5.50). Low‐pressure air and HPA dusters had shorter operating time than the commercial dusters (1 second per burrow versus = 7.69, 95% CI = 7.42–7.95, P ≤ 0.01). Mean flea abundance and prevalence of flea infestation in 2021 was lower on the site dusted with prototype LPA dusters ( = 0.13 fleas, 95% CI = 0.00–0.31, prevalence = 0.065) than on a non‐dusted site ( = 8.61 fleas, 95% CI = 6.05–11.17, P ≤ 0.01, prevalence = 1.0). The LPA dusters offer several advantages over previous duster designs, including continuously generated low‐pressure compressed air, a durable build, and efficient operation from ATVs. Future work should focus on calibration at higher doses of dust and assessment of larger air tanks and more durable fuse systems. Accurate and efficient equipment along with quality control monitoring are vital to the ongoing success of vector control as a plague management tool.

Disease and weather induce rapid shifts in a rangeland ecosystem mediated by a keystone species (Cynomys ludovicianus).

Habitat loss and changing climate have direct impacts on native species but can also interact with disease pathogens to influence wildlife communities. In the North American Great Plains, black-tailed prairie dogs (Cynomys ludovicianus) are a keystone species that create important grassland habitat for numerous species and serve as prey for predators, but lethal control driven by agricultural conflict has severely reduced their abundance. Novel disease dynamics caused by epizootic plague (Yersinia pestis) within prairie dog colonies have further reduced prairie dog abundances, in turn destabilizing associated wildlife communities. We capitalized on a natural experiment, collecting data on prairie dog distributions, vegetation structure, avian abundance, and mesocarnivore and ungulate occupancy before (2015-2017) and after (2018-2019) a plague event in northeastern Wyoming, USA. Plague decimated black-tailed prairie dog populations in what was then the largest extant colony complex, reducing colony cover in the focal area from more than 10,000 ha to less than 50 ha. We documented dramatic declines in mesocarnivore occupancy and raptor abundance post-plague, with probability of occupancy or abundance approaching zero in species that rely on prairie dogs for a high proportion of their diet (e.g., ferruginous hawk [Buteo regalis], American badger [Taxidea taxus], and swift fox [Vulpes velox]). Following the plague outbreak, abnormally high precipitation in 2018 hastened vegetation recovery from prairie dog disturbance on colonies in which constant herbivory had formerly maintained shortgrass structure necessary for certain colony-associates. As a result, we observed large shifts in avian communities on former prairie dog colonies, including near-disappearance of mountain plovers (Charadrius montanus) and increases in mid-grass associated songbirds (e.g., lark bunting [Calamospiza melanocorys]). Our research highlights how precipitation can interact with disease-induced loss of a keystone species to induce drastic and rapid shifts in wildlife communities. Although grassland taxa have co-evolved with high spatiotemporal variation, fragmentation of the remaining North American rangelands paired with higher-than-historical variability in climate and disease dynamics are likely to destabilize these systems in the future.

Grasshopper Species Composition Differs Between Prairie Dog Colonies and Undisturbed Sites in a Sagebrush Grassland

Grasshoppers are major consumers of plant biomass in grassland and shrubland ecosystems. While often considered generalists, grasshopper species have differing habitat preferences and interactions with other consumers in grasslands. There are conflicting accounts of how prairie dog colonies and differences in vegetation impact grasshopper abundance and composition. We conducted a landscape-scale survey of grasshopper communities, plant communities, and prairie dogs in a grassland/shrubland ecosystem in eastern Wyoming. Over the study landscape, spurthroat grasshoppers (Melanoplinae) were associated with lower sagebrush cover and lower cover of C3 perennial graminoids, bandwing grasshoppers (Oedipodinae) were associated with low-lying areas with a high cover of C4 grasses and a low cover of cheatgrass, and slantface grasshoppers (Gomphocerinae) were associated with low vegetation height. Prairie dogs, presumably because of their effects on vegetation, had different impacts on different groups of grasshoppers. Melanoplinae grasshoppers, the Wyoming toothpick grasshopper (Paropomala wyomingensis Thomas), and grasshoppers with early-season phenology were associated with prairie dog colonies. However, because some species of grasshoppers were positively and others negatively associated with prairie dogs, the net effect of prairie dogs on total grasshopper biomass was neutral. Thus, to determine the role of grasshoppers in prairie ecosystems, it will be important to determine whether there is functional equivalence of grasshopper species in consuming plant biomass and as food for vertebrates.

Evaluating Prairie Dog–Cattle Competition from the Perspective of a Ranching Enterprise in the Western Great Plains: Economic Analysis of Potential Effects on Long-Term Profitability

Prairie dogs and livestock have long been viewed as competitors for forage resources, causing widespread exterminations of prairie dogs, resulting in the decline of other threatened and endangered wildlife species. In this study we model the impacts that prairie dogs exhibit on the long-term profitability and cow herd dynamics of a ranch over a 40-yr production period on a representative cow-calf ranch operation in the Thunder Basin Ecoregion of Wyoming. More specifically, we evaluate the effects of prairie dogs on a cow-calf operation through two forage/livestock use assumptions; the first is simply loss of forage due to prairie dog consumption, and the second scenario assumes there is no available forage for livestock on prairie dog colonies. We also include three different potential prairie dog population dynamic scenarios: unmanaged prairie dogs, unmanaged prairie dogs with increased colony expansion during drought, and prairie dogs managed for a target colony size. As expected, our results indicate that prairie dogs decrease forage availability for grazing, thus reducing the average cow herd size on a ranch, the annual returns from livestock sales, and the maximized net present value of annual returns. Further, the magnitude of these impacts and the financial feasibility of managing prairie dogs largely depends on the effects prairie dogs exhibit on forage resources and how cattle use these forage resources.

Potential Effects of Environmental Conditions on Prairie Dog Flea Development and Implications for Sylvatic Plague Epizootics.

Fleas are common ectoparasites of vertebrates worldwide and vectors of many pathogens causing disease, such as sylvatic plague in prairie dog colonies. Development of fleas is regulated by environmental conditions, especially temperature and relative humidity. Development rates are typically slower at low temperatures and faster at high temperatures, which are bounded by lower and upper thresholds where development is reduced. Prairie dogs and their associated fleas (mostly Oropsylla spp) live in burrows that moderate outside environmental conditions, remaining cooler in summer and warmer in winter. We found burrow microclimates were characterized by stable daily temperatures and high relative humidity, with temperatures increasing from spring through summer. We previously showed temperature increases corresponded with increasing off-host flea abundance. To evaluate how changes in temperature could affect future prairie dog flea development and abundance, we used development rates of O. montana (a species related to prairie dog fleas), determined how prairie dog burrow microclimates are affected by ambient weather, and combined these results to develop a predictive model. Our model predicts burrow temperatures and flea development rates will increase during the twenty-first century, potentially leading to higher flea abundance and an increased probability of plague epizootics if Y. pestis is present.

Boom and bust cycles of black-tailed prairie dog populations in the Thunder Basin grassland ecosystem

AbstractBlack-tailed prairie dogs (Cynomys ludovicianus) exhibit boom and bust cycles in landscapes where they are affected by outbreaks of plague caused by the introduced bacterium Yersinia pestis. We examined spatiotemporal dynamics of black-tailed prairie dog colonies in the Thunder Basin National Grassland, Wyoming over a period of 21 years. The colony complex experienced three plague epizootics during that time, and consequently three boom and bust cycles. The entire prairie dog colony complex collapsed over a 1-year period during the first and third epizootics, and over a 3-year period during the second epizootic. The boom and bust cycles were characterized by relatively rapid contractions in total area occupied by prairie dogs during a plague outbreak (e.g., >99% decline from 10,604 ha to 47 ha over 1 year [2017–2018]) followed by much slower recovery times (e.g., an increase from 410 ha to 10,604 ha over 11 years [2006–2017]). Prairie dogs occupied a total of 10,604 ha during at least one survey within the study period, but much of the area was not continuously occupied over time. We found that each of the three plague outbreaks occurred in years with highly connected prairie dog colonies and slightly above-average temperatures and summer precipitation, which were preceded by a dry year. Although plague outbreaks were associated with climatic conditions, we were unable to detect a role of climate in driving colony expansion. Our results illustrate the cyclic and extreme nature of fluctuations in black-tailed prairie dog colony size and distribution in a landscape where plague occurs and illuminate some of the drivers of these cycles. Further, our work shows how introduced diseases can dramatically influence populations of a keystone species, with important consequences for the broader ecological system.

Prairie dogs, cattle subsidies and alternative prey: seasonal and spatial variation in coyote diet in a temperate grassland

As the dominant predator on North America's grasslands, coyotes Canis latrans have a large influence on biodiversity, both on working ranches and in protected parks. Ground squirrel (sciurid) species and livestock carrion are often abundant on grasslands worldwide and have the potential to influence a predator's consumption of alternative prey. We collected 1321 scats in four seasons over two years in and adjacent to Grasslands National Park, Saskatchewan, to test the hypothesis that seasonal and spatial variation in consumption of sciurid prey and cattle Bos taurus carrion influenced coyote consumption of alternative prey. Sciurid (black‐tailed prairie dog Cynomys ludovicianus and Richardson's ground squirrel Urocitellus richardsonii) remains were common from spring to fall and had a strong inverse relationship with deer (mule deer Odocoileus hemionus and white‐tailed deer O. virginianus), which were most common in winter scats. Cattle remains were most common during spring, fall and winter, and occurred in 10.6% of scats annually. Biomass estimates suggest that cattle was the highest ranked food on cattle grazing land year‐round, and the 2nd ranked food, after deer, during winter on the portion of the park from which cattle were excluded. Closer proximity of scats to a prairie dog colony increased the likelihood of prairie dog remains throughout the year and reduced the likelihood of cattle remains in scats from spring to fall, but not during winter. Individual differences in foraging and ranging behavior may explain the spatial distribution of prairie dog versus cattle in scats. Further work is needed to determine whether sciurid prey, deer, or livestock carrion support large predator populations on grassland habitats to a level that may negatively affect coexisting prey species, including species at risk.

Unique utilisation pattern responses of five sympatric ungulates to local phenological gradients

Context Ungulate life-history strategies and behaviour are driven by two dominant factors, namely, acquisition of nutrients and avoidance of predation. Although many studies have investigated single species resource/habitat selection, there are still gaps in our understanding of multi-species systems and resource partitioning. Aim We explored the habitat selection of five sympatric resident ungulates in relation to seasonal phenological gradients in a temperate grassland (Northern Great Plains) system. We identified and compared habitat-utilisation strategies across the vegetation-growing season and related to established forage acquisition hypotheses. Methods We collected ungulate detection data during two field seasons (July–October 2018, May–September 2019) across 202 sites and deployed 1202 cameras (29 284 camera-nights). We modelled ungulate detections in relation to normalised difference vegetation index (NDVI) and NDVI slope (rate and direction of change) to learn about ungulate resource selection in four habitat types (grass, prairie dog colonies, forest and riparian). Results We found unique foraging strategies for each of the focal species throughout the growing season (spring, summer, early autumn), which resulted in seasonal partitioning of resources among sympatric ungulate species. Conclusions The temporal and spatial patterns observed emphasise that multiple species can experience the same vegetation phenology and respond differently in their movements and foraging behaviour. At local scales, some ungulates selected for higher forage quantity (selection of higher NDVI) and some for higher forage quality (selection of positive NDVI slope or greening up). Implications The unique foraging strategies presented here indicated that generalisations are problematic when managing wildlife resources and emphasise the need to conduct multi-species studies to understand resource utilisation at local scales. Furthermore, understanding variation in foraging strategies of resident sympatric species can direct management planning where decreased connectivity or loss of migration pathways alters traditional behaviours.

Fine-Scale Spatial Structure of Soil Microbial Communities in Burrows of a Keystone Rodent Following Mass Mortality

Soil microbial communities both reflect and influence biotic and abiotic processes occurring at or near the soil surface. Ecosystem engineers that physically alter the soil surface, such as burrowing ground squirrels, are expected to influence the distribution of soil microbial communities. Black-tailed prairie dogs (Cynomys ludovicianus) construct complex burrows in which activities such as nesting, defecating, and dying are partitioned spatially into different chambers. Prairie dogs also experience large-scale die-offs due to sylvatic plague, caused by the bacterium Yersinia pestis, which lead to mass mortality events with potential repercussions on microbial communities. We used 16S sequencing to examine microbial communities in soil that was excavated by prairie dogs from different burrow locations, and surface soil that was used in the construction of burrow entrances, in populations that experienced plague die-offs. Following the QIIME2 pipeline, we assessed microbial diversity at several taxonomic levels among burrow regions. To do so, we computed community similarity metrics (Bray–Curtis, Jaccard, and weighted and unweighted UniFrac) among samples and community diversity indexes (Shannon and Faith phylogenetic diversity indexes) within each sample. Microbial communities differed across burrow regions, and several taxa exhibited spatial variation in relative abundance. Microbial ecological diversity (Shannon index) was highest in soil recently excavated from within burrows and soils associated with dead animals, and was lowest in soils associated with scat. Phylogenetic diversity varied only marginally within burrows, but the trends paralleled those for Shannon diversity. Yersinia was detected in four samples from one colony, marking the first time the genus has been sampled from soil on prairie dog colonies. The presence of Yersinia was a significant predictor of five bacterial families and eight microbial genera, most of which were rare taxa found in higher abundance in the presence of Yersinia, and one of which, Dictyostelium, has been proposed as an enzootic reservoir of Y. pestis. This study demonstrates that mammalian modifications to soil structure by physical alterations and by mass mortality can influence the distribution and diversity of microbial communities.

Comparison of Flea Sampling Methods and Yersinia pestis Detection on Prairie Dog Colonies.

Scientists collect fleas (Siphonaptera) to survey for Yersinia pestis, the bacterial agent of plague. When studying fleas parasitizing prairie dogs (Cynomys spp.), two primary methods are used: (1) combing fleas from live-trapped prairie dogs and (2) swabbing fleas from burrows with cloth swabs attached to metal cables. Ideally, burrow swabbing, the cheaper and easier method, would explain flea burdens on prairie dogs and provide reliable information on plague prevalence. In a linear regression analysis of data from 1-month intervals (June-August 2010-2011) on 13 colonies of black-tailed prairie dogs (Cynomys ludovicianus, BTPDs) in New Mexico, flea abundance on swabs explained 0-26% of variation in BTPD flea burdens. In an analysis of data (May-August 2016) from six colonies of BTPDs in Montana, flea abundance on swabs explained 2% of variation in BTPD flea burdens. In an analysis of data from a short-term interval (July 23-27, 2019) on four colonies of BTPDs in Montana, flea abundance on swabs explained 0.1% of variation in BTPD flea burdens. In an analysis of data from 1-week intervals (August-October 2000) on four colonies of white-tailed prairie dogs (Cynomys leucurus, WTPD) in Utah, swabbing data explained 0.1% of variation in WTPD flea burdens. Pools of fleas from two WTPD colonies were tested for Y. pestis by mouse inoculation and isolation; 65% from WTPDs tested positive, whereas 4% from burrows tested positive. Data herein also show that results from burrow swabbing can misrepresent flea species composition and phenology on prairie dogs. Burrow swabbing is useful for some purposes, but limitations should be acknowledged, and accumulated data should be interpreted with caution.

Long‐Term Effects of Black‐Tailed Prairie Dogs on Livestock Grazing Distribution and Mass Gain

ABSTRACTThe conservation and management of black‐tailed prairie dogs (Cynomys ludovicianus) have been contentious issues in grasslands of central North America for much of the past century, primarily because of the perception that they compete with livestock for forage. Studies quantifying the magnitude of competition between prairie dogs and cattle are difficult to conduct because of the large spatial and long temporal scales needed to quantify how competition varies in response to interannual variation in precipitation and prairie dog abundance. We examined variation in mass gains of yearling steers in shortgrass steppe of northeastern Colorado, USA, with and without prairie dogs from 2008–2019, a period that encompassed a full cycle in prairie dog abundance from a nadir following plague‐induced population collapse, to peak abundance following population recovery, to plague‐induced population lows again. Analyses of cattle grazing distribution with global positioning system (GPS)‐collars revealed preferential grazing on colonies following a period of unusually high vegetation production, and preferential grazing off colonies following a period of rapid vegetation senescence, but these patterns were not clearly related to cattle mass gains. Across all 12 years of the study, average daily mass gain (ADG) during the growing season was 0.97 kg/steer/day in pastures where prairie dogs were controlled annually, and 0.95 kg/steer/day in pastures where they were not. Average daily mass gain was a quadradic function of precipitation and a linear function of prairie dog occupancy within a pasture, with a generalized linear mixed model predicting an 8.0% decrease in ADG as prairie dog occupancy increased from 0 to 60% of a pasture with average growing‐season precipitation. We did not detect a significant interaction between precipitation and prairie dog occupancy, but one limitation of our study is that the only drought year (2012) occurred when prairie dogs occupied low percentages (10–25%) of the study pastures. Prairie dogs had a small but detectable negative effect on cattle mass gains during the growing season in shortgrass steppe. The magnitude of this effect can be used by managers in combination with market conditions and the spatial extent of prairie dog colonies to estimate economic effects of prairie dogs on livestock operations. © 2021 The Wildlife Society. This article is a U.S. Government work and is in the public domain in the USA.

Soil carbon and plant richness relationships differ among grassland types, disturbance history and plant functional groups

Understanding the relationship of soil carbon storage and species diversity in grasslands can provide insights into managing these ecosystems. We studied relationships among soil C and plant species richness within ~ 9700 ha of grasslands in Colorado, US. Using 141 grassland transects, we tested how soil C was related to plant species richness, grassland type, soil texture, and prairie dog presence. Soil C was significantly, positively related to plant species richness, while native perennial graminoid species richness exhibited an even stronger positive relationship. However, the relationship of soil C and plant richness was not found in all three grassland types studied, but instead was unique to the most common grassland type, mixed grass prairie, and absent from both xeric tallgrass and mesic tallgrass prairie. The presence of a single indicator species, Andropogon gerardii, showed a significant, positive relationship with soil carbon. Our best possible model explained 45% of the variance in soil C using species richness, grassland type, and their interaction. Surprisingly, soil C was negatively related to soil clay, suggesting that surface clays amplify evaporation and water runoff rather than protecting soil organic matter from decomposition. Soil C was negatively related to prairie dog presence, suggesting that prairie dogs do not enhance soil carbon sequestration; in fact, prairie dog occupied sites had significantly lower soil C, likely related to loss of topsoil from prairie dog colonies. Our results suggest that management for species richness provides the co-benefit of soil C storage, and high clay and prairie dog disturbance compromises both.

Do black‐tailed prairie dog (Cynomys ludovicianus) colonies attract foraging bats?

AbstractBlack‐tailed prairie dog (BTPD) colonies are known to be hotbeds of biodiversity. Manipulation of landscape by BTPDs increases plant and animal diversity in grasslands, and thus BTPDs are considered ecosystem engineers. If BTPD colonies induce increases in insect diversity in the eastern foothills of Colorado, as shown for other areas, it stands to reason that insectivorous bats may respond by increasing their activity in those areas. I tested this hypothesis in the north‐eastern foothills habitat of Colorado, USA, by surveying for echolocation calls within four BTPD colonies and adjacent reference sites lacking BTPD burrows. Results show that bats were significantly more active in BTPD colonies than at adjacent reference sites. In addition, of the nine resident bat species, small‐footed myotis (Myotis ciliolabrum) showed the most consistent relationship with BTPD colonies. Other species that were more active in BTPD colonies included little brown myotis (M. lucifugus), fringed myotis (M. thysanodes), big brown bats (Eptesicus fuscus), and hoary bats (Lasiurus cinereus). The typically forest‐edge adapted species, M. ciliolabrum, and M. thysanodes a forest‐adapted specialist, were active more than expected in treeless BTPD colonies indicating the BTPD colonies are providing a resource not present outside colony perimeters. This study provides the first evidence of a relationship between BTPD colonies and bats in western North America.

Determinants of social structure in a northern population of black-tailed prairie dogs, Cynomys ludovicianus

Animal sociality can vary in response to both biotic and abiotic factors, and variation in the rate and types of interactions that occur between individuals of a group can result in greatly differentiated social structure and ultimately social evolution. However, social structures are often generalized to the species or population level and do not consider potential shifts in structure over time. We used social network analysis to investigate the social structure of black-tailed prairie dogs (hereafter ‘prairie dogs’) and determine the demographic features that may underpin the observed social structures in a population that experiences increased seasonal shifts of environmental conditions compared to populations in the centre of the geographical range. Prairie dogs live in highly social colonies, display an elaborate range of social behaviours and experience very dynamic changes in body condition due to variable environmental conditions. We used exponential random graph models (ERGMs) to examine the effects of body condition, age, sex and spatial arrangement on static and temporal social networks. We expected that spatial arrangement would most strongly influence social structure given the delineated burrow systems of a prairie dog colony. We hypothesized that body condition influences social structure over time, where those in better body condition maintain the social structure. Prairie dogs associated preferentially with individuals near themselves and of the same age. Furthermore, we also determined that body condition correlated positively with maintaining social structure over time, where those in poorer body condition experienced an increase in the loss and gain of relationships compared to those in better body condition that maintained connections. Our study confirms previous conclusions of association based on age and also highlights the importance of considering dynamic individual traits such as body condition in the importance of long-term social structure. These results also show the promise of both static and temporal ERGMs in a biological system and demonstrate the potential for increased temporally driven hypothesis testing using this technique. • Social structure of black-tailed prairie dogs is more variable than previously thought. • Body condition contributed to maintenance of social connectivity over time. • Age and sex influenced the targets of affiliative and agonistic behaviours. • Individuals tended to associate with nearby coterie members of the same age.

No evidence for enzootic plague within black-tailed prairie dog (Cynomys ludovicianus) populations.

Yersinia pestis, causative agent of plague, occurs throughout the western United States in rodent populations and periodically causes epizootics in susceptible species, including black‐tailed prairie dogs (Cynomys ludovicianus). How Y. pestis persists long‐term in the environment between these epizootics is poorly understood but multiple mechanisms have been proposed, including, among others, a separate enzootic transmission cycle that maintains Y. pestis without involvement of epizootic hosts and persistence of Y. pestis within epizootic host populations without causing high mortality within those populations. We live‐trapped and collected fleas from black‐tailed prairie dogs and other mammal species from sites with and without black‐tailed prairie dogs in 2004 and 2005 and tested all fleas for presence of Y. pestis. Y. pestis was not detected in 2126 fleas collected in 2004 but was detected in 294 fleas collected from multiple sites in 2005, before and during a widespread epizootic that drastically reduced black‐tailed prairie dog populations in the affected colonies. Temporal and spatial patterns of Y. pestis occurrence in fleas and genotyping of Y. pestis present in some infected fleas suggest Y. pestis was introduced multiple times from sources outside the study area and once introduced, was dispersed between several sites. We conclude Y. pestis likely was not present in these black‐tailed prairie dog colonies prior to epizootic activity in these colonies. Although we did not identify likely enzootic hosts, we found evidence that deer mice (Peromyscus maniculatus) may serve as bridging hosts for Y. pestis between unknown enzootic hosts and black‐tailed prairie dogs.