Prairie Dog Colonies Research Articles

Epizootic Plague in Prairie Dogs: Correlates and Control with Deltamethrin.

The plague bacterium, Yersinia pestis, is a generalist pathogen of flea (Siphonaptera) vectors and mammalian hosts. In colonies of prairie dogs (PDs, Cynomys spp.), Y. pestis causes occasional epizootics, killing ≥90% of PDs within weeks to several months. We evaluated the effectiveness of deltamethrin, a pyrethroid insecticide, as a tool for preventing plague epizootics among three PD species. Specifically, we studied PD population growth on paired plots treated with deltamethrin for flea control or left untreated as baselines. We also evaluated PD population growth relative to flea abundance and PD density. All epizootics occurred on nontreated plots. Epizootics occurred on plots with very low PD densities as well as high densities. Mean population change, assessed by comparing visual counts of PDs in years before and during epizootics, was +88% for treated plots and -97% for nontreated plots. For comparison, an experimental oral vaccine against plague had an average change in population index or estimate during epizootics of -69% on vaccine plots compared with -83% for associated nontreated (placebo) plots. In our study and on plots not treated with deltamethrin, PD population growth was negatively correlated with flea abundance in the year before the epizootic, lending support to the hypothesis that flea abundance plays a critical role in plague transmission under natural conditions. Generally speaking, deltamethrin is a highly effective tool for plague management on PD colonies. That said, continued study is needed to refine deltamethrin treatments and to develop a more integrated strategy for plague management.

Dialects in the alarm calls of black- tailed prairie dogs (Cynomys ludovicianus): A case of cultural diffusion?

Prairie dogs (Cynomys spp.) produce an alarm call when a predator appears. Gunnison’s prairie dogs (Cynomys gunnisoni) produce calls that vary in spectral structure according to predator type and specific characteristics unique to the individual predator, such as color and shape. These calls vary depending on geographic location and have been characterized as dialects. Black-tailed prairie dogs (Cynomys ludovicianus) also encode information about terrestrial predators in their alarm calls. However, nothing is known about whether there are dialects in these alarm calls, and if so, why these dialects might have arisen. We studied the alarm calls and habitat characteristics of eight different black-tailed prairie dog colonies within the Southwestern USA: Maxwell National Wildlife Refuge, NM, Vermejo Park Ranch, NM, Kiowa National Grasslands, NM, Rita Blanca National Grasslands, TX, and Comanche National Grasslands, CO. An analysis of time and frequency changes in alarm calls showed that colony sites that were located within 30 km each other did not have significant differences in alarm call structure, but sites that were more distant were significantly different from the other sites, consistent with the existence of dialects as well as with genetic models of isolation by distance. The acoustic structure of the alarm calls was not explained by differences in habitat characteristics at each site. A comparison of Squared Euclidian Distances (D2) of alarm calls versus linear distances between sites showed a significant positive correlation, implying that alarm call dialect differences increase the farther one site is from another. This relationship is consistent with a cultural diffusion model of dialects, and is similar to that observed in human dialects.

An invasive disease, sylvatic plague, increases fragmentation of black-tailed prairie dog (Cynomys ludovicianus) colonies.

A disease can be a source of disturbance, causing population declines or extirpations, altering species interactions, and affecting habitat structure. This is particularly relevant for diseases that affect keystone species or ecosystem engineers, leading to potentially cascading effects on ecosystems. We investigated the invasion of a non-native disease, plague, to a keystone species, prairie dogs, and documented the resulting extent of fragmentation and habitat loss in western grasslands. Specifically, we assessed how the arrival of plague in the Conata Basin, South Dakota, United States, affected the size, shape, and aggregation of prairie dog colonies, an animal species known to be highly susceptible to plague. Colonies in the prairie dog complex were mapped every 1 to 3 years from 1993 to 2015. Plague was first confirmed in 2008 and we compared prairie dog complex and colony characteristics before and after the arrival of plague. As expected the colony complex and the patches in colonies became smaller and more fragmented after the arrival of plague; the total area of each colony and the mean area per patch within a colony decreased, the number of patches per colony increased, and mean contiguity of each patch decreased, leading to habitat fragmentation. We demonstrate how an emerging infectious disease can act as a source of disturbance to natural systems and lead to potentially permanent alteration of habitat characteristics. While perhaps not traditionally thought of as a source of ecosystem disturbances, in recent years emerging infectious diseases have shown to be able to have large effects on ecosystems if they affect keystone species.

Relentless Predation on Gunnison's Prairie Dogs (Cynomys Gunnisoni) by a Single American Badger (Taxidea Taxus)

Predation affects the demography and population dynamics of prey species. Because predators commonly stalk prey from concealed routes, attack quickly, and frequently avoid areas with human observers, documenting predation under natural conditions is often difficult. An adult female American badger (Taxidea taxus) with offspring moved into a colony of Gunnison's prairie dogs (Cynomys gunnisoni) living under natural conditions at Valles Caldera National Preserve in New Mexico, United States, and provided an excellent opportunity to record predations over a period of 33 consecutive days in June–July 2018. Badgers are commonly nocturnal, but the badger at our study area captured a total of 100 Gunnison's prairie dogs during daylight hours. Sixty-two of the victims were adults (≥1 year old), 32 were juveniles (≤3 months since birth), and 6 were of unknown age. Most predations occurred in mid-morning and early afternoon. Our results, which do not account for nighttime predations and therefore underestimate numbers of successful attacks, suggest that a single predatory individual can have a sudden, devastating effect on a prey species.

Drought-mediated changes in black-tailed prairie dog colonies in the Northern Great Plains

Abstract Populations of many mammal species living in grassland ecosystems across North America have been reduced greatly over the past 200 years due to conversion of native prairie to human-related uses. Foremost among these species is the black-tailed prairie dog (Cynomys ludovicianus), populations of which have declined an estimated 98% during that time. In addition to anthropogenic factors including plague, black-tailed prairie dog populations can vary in size in response to grazing by native ungulates, fire, and precipitation. Colonies in the Northern Great Plains have expanded and contracted during dry and wet periods, respectively. Drought reduces vegetation height; tall vegetation is known to limit colony expansion, possibly due to increased predation risk. We used mixed-effects models to analyze data sets of colony areas of black-tailed prairie dogs spanning 16–22 years and 983 total colony counts, from 142 unique colonies at Badlands National Park and Wind Cave National Park, South Dakota, United States, and Scotts Bluff National Monument, Nebraska, United States, to relate areal dynamics of colonies over time to total annual precipitation, drought stress, and plague. We also analyzed the relationship between active-burrow densities and precipitation and drought stress using 7 years of data from 271 colony counts at Badlands National Park. Black-tailed prairie dog colonies expanded in response to drought conditions in all three national parks, with colonies in Wind Cave National Park exhibiting a time-delayed response. In addition, colony area was negatively related to total accumulated precipitation for the preceding 12 months for Scotts Bluff National Monument. Active-burrow density at Badlands National Park decreased in response to drought stress with a time lag of 24–36 months. Plague first was reported at Badlands National Park in 2008 and colony areas decreased dramatically and rapidly during plague epizootic events. Our results support observations that black-tailed prairie dog colonies in the Northern Great Plains expand and contract in response to drought stress and wet weather. Furthermore, our findings provide new insights into the role of climate on a keystone species of conservation importance and demonstrate the value of collecting long-term ecological data.

Black-Tailed Prairie Dog (Cynomys ludovicianus) Reintroduction Can Limit Woody Plant Proliferation in Grasslands

Tree and shrub proliferation has been widespread in grasslands worldwide, and has altered ecosystem function and wildlife habitat. Several causes have been proposed for the woody plant encroachment phenomenon. The widespread eradication of a native keystone herbivore in North American grasslands, the prairie dog (Cynomys spp.), is one potential contributing factor that has received relatively little attention. We hypothesized prairie dogs would have historically suppressed woody plants by creating “browse traps” through their systematic clipping of vegetation. We tested this hypothesis by conducting surveys and experimentally manipulating shrub accessibility via exclosures and artificial saplings on and around recently reestablished black-tailed prairie dog (C. ludovicianus) colonies in southeastern Arizona, USA. Shrubs were common on the nascent colonies (mean ± SE = 132 ± 32.7 plants ha-1), but at substantially reduced densities compared to off colonies (305 ± 94.9 plants ha-1). Among branches placed on colonies to simulate ‘saplings’, 89% were damaged within three days of ‘planting’, whereas those placed off colonies were virtually untouched. This was true for both a deciduous, N2-fixing shrub (velvet mesquite, Prosopis velutina) and an evergreen non-N2-fixing shrub (creosote bush, Larrea tridentata). Prairie dogs on newly established colonies did not extirpate woody plants over the time-frame of our study, but reduced their abundance and suppressed their growth, which would ostensibly prevent them from achieving dominance. Implications for extending the longevity of widely practiced ‘brush management’ grassland restoration treatments are discussed in the context of perceptions of prairie dogs as rangeland pests. Prairie dogs represent an enigma in keystone conservation. Whereas the reintroduction of large or charismatic keystone species (e.g. sea otters [Enhydra lutris]) are conducted to restore critical ecological function, reintroductions of other keystone species, such as gray wolves [Canis lupus] and in our case, prairie dogs, are highly controversial. Our findings suggest reintroductions of this negatively perceived small herbivore could function as a tool to locally suppress woody plant proliferation that is widely regarded as an impediment to livestock production. Accordingly, prairie dogs could promote restoration efforts to re-establish and maintain habitat for grassland endemics while promoting biological diversity and other ecosystem services.

Managing plague on prairie dog colonies: insecticides as ectoparasiticides

Human health practitioners and wildlife biologists use insecticides to manage plague by suppressing fleas (Siphonaptera), but insecticides can also kill other ectoparasites. We investigated effects of deltamethrin and fipronil on ectoparasites from black-tailed prairie dogs (Cynomys ludovicianus, BTPDs). In late July, 2018, we treated three sites with 0.05% deltamethrin dust and 5 sites with host-fed 0.005% fipronil grain. Three non-treated sites functioned as experimental baselines. We collected ectoparasites before treatments (June-July, 2018) and after treatments (August-October, 2018, June-July, 2019). Both deltamethrin and fipronil suppressed fleas for at least 12 months. Deltamethrin had no detectable effect on mites (Arachnida). Fipronil suppressed mites for at least 12 months. Lice (Phthiraptera) were scarce on non-treated sites throughout the study, complicating interpretation. Concentrating on eight sites where all three ectoparasites where found in June-July, 2018 (before treatments), flea intensity was greatest on BTPDs carrying many lice and mites. These three ectoparasites co-occurred at high numbers, which might facilitate plague transmission in some cases. Lethal effects of insecticides on ectoparasite communities are potentially advantageous in the context of plague management.

A Comparison of Two Methods to Monitor Translocated Prairie Dogs

ABSTRACTThe effects of sylvatic plague and habitat fragmentation present species conservation challenges for prairie dogs (Cynomys spp.) and other wildlife species they support. Active reestablishment of extirpated prairie dog colonies may become increasingly necessary to achieve some conservation goals. We compared a passive‐integrated‐transponder (PIT) tag monitoring system and trail camera photographs to monitor short‐term survival of captive dye‐marked black‐tailed prairie dogs (Cynomys ludovicianus) translocated into artificial burrows. We deployed cameras and a PIT‐tag monitoring system in 2016 and 2017 (Nov–Sep) and collected 1.2 million PIT‐tag scans and >255,000 photographs at a Colorado Parks and Wildlife facility near Fort Collins, Colorado, USA. There was no difference in the daily mean number of prairie dogs detected between the 2 monitoring methods (photographs = 3.40, PIT tags = 4.06). However, PIT‐tag scans achieved a population census in 10 days (100% detected, 95% CI = 89–100%); whereas, photographs were able to detect only 67% of the prairie dogs during this same time (95% CI = 50–80%). Trail camera photographs of uniquely dye‐marked individuals may be ideal for short‐term monitoring (≤6 months), while PIT tags are likely to outperform cameras in studies requiring efficient longer term monitoring of permanently marked prairie dogs. Although both monitoring techniques performed well in a semicaptive setting, how these techniques would perform when scaled to larger or more complex settings requires further research. © 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Comparing stability in random forest models to map Northern Great Plains plant communities in pastures occupied by prairie dogs using Pleiades imagery

Abstract. Black-tailed prairie dogs (Cynomys ludovicianus) have been described as a keystone species and are important for grassland conservation, yet many concerns exist over the impact of prairie dogs on plant biomass production and consequently livestock production. The ability to map plant communities in pastures colonized by prairie dogs can provide land managers with an opportunity to optimize rangeland production while balancing conservation goals. The aim of this study was to test the ability of random forest (RF) models to classify five plant communities located on and off prairie dog towns in mixed-grass prairie landscapes of north central South Dakota, assess the stability of RF models among different years, and determine the utility of utilizing remote sensing techniques to identify prairie dog colony extent. During 2015 and 2016, Pleiades satellites were tasked to image the study site for a total of five monthly collections each summer (June–October). Training polygons were mapped in 2016 for the five plant communities and used to train RF models. Both the 2015 and 2016 RF models had low (1 %) out-of-bag error rates. However, comparisons between the predicted plant community maps using the 2015 imagery and one created with the 2016 imagery indicate over 32.9 % of pixels changed plant community class between 2015 and 2016. The results show that while RF models may predict with a high degree of accuracy, overlap of plant communities and interannual differences in rainfall may cause instability in fitted models. A final RF model combining both 2015 and 2016 data yielded the lowest error rates and was also highly accurate in determining prairie dog colony boundaries.

Mountain Plover habitat selection and nest survival in relation to weather variability and spatial attributes of black-tailed prairie dog disturbance

Abstract Habitat loss and altered disturbance regimes have led to declines in many species of grassland and sagebrush birds, including the imperiled Mountain Plover (Charadrius montanus). In certain parts of their range Mountain Plovers rely almost exclusively on black-tailed prairie dog (Cynomys ludovicianus) colonies as nesting habitat. Previous studies have examined Mountain Plover nest and brood survival on prairie dog colonies, but little is known about how colony size and shape influence these vital rates or patterns of habitat selection. We examined how (1) adult habitat utilization, (2) nest-site selection, and (3) nest success responded to a suite of local- and site-level variables on large prairie dog colony complexes in northeastern Wyoming. Abundance of adult Mountain Plovers was highest on points within older, “medium”-sized (100–500 ha) colonies with high cover of annual forbs and bare ground (5.8 birds km−2), but lower on extremely large (>2,000 ha) colonies (2.1 birds km−2). Nest sites were characterized by high proportions of annual forbs and bare ground and low cactus cover and vegetation height. Nest survival was higher for older nests, and nests with lower cactus cover, and decreased with increasing temperatures. Uncertainty was high for models of daily nest survival, potentially because of 2 competing sources of nest failure: nest depredation and nest abandonment or inviability of eggs. Drivers of these 2 sources of nest failure differed, with inclement weather and higher temperatures associated with nest abandonment or egg inviability. We highlight how prairie dogs alter vegetation structure and bare ground heterogeneously across the landscape, and how this in turn influences bird abundance and nest distribution at different temporal and spatial scales. Furthermore, our work reveals how partitioning the causes of nest failure during nest survival analyses enhances understanding of survival rate covariates.

Modeling control methods to manage the sylvatic plague in black‐tailed prairie dog towns

AbstractBlack‐tailed prairie dogs (Cynomys ludovicianus) are a keystone species of shortgrass and midgrass prairies, and they are essential for successful reintroduction efforts of endangered black‐footed ferrets (Mustela nigripes). Sylvatic plague extirpates black‐tailed prairie dog colonies. We present a model to determine optimal control methods to sustain a black‐tailed prairie dog colony against the plague, including a recently developed vaccine. Our host submodel is a susceptible, exposed, infectious, vaccinated model, and our vector submodel is a susceptible, exposed, early‐stage and late‐stage infectious model with questing and on‐host vectors. Both submodels are hybrid ordinary differential and difference equation models to reflect the phenology of black‐tailed prairie dogs. Our model suggests vaccination efforts can substantially outperform previous control methods (e.g. reactive insecticidal dusting). Our model suggests that a vaccine that provides 18 months of immunity, administered annually, starting one year before an outbreak, can efficiently sustain a black‐tailed prairie dog colony against the plague.Recommendations for resource managers The current sylvatic plague vaccine, administered annually, is insufficient to protect a black‐tailed prairie dog colony against the sylvatic plague. Developing a vaccine with an immunity period of 18 months is critical for the persistence of a colony against the plague. While insecticidal dusting appears unable to assist in helping a black‐tailed prairie dog colony recover from a plague outbreak, insecticidal dusting is still a critical prevention tool as plague transmission from the prairie dog flea is capable of causing a plague outbreak by itself. Black‐tailed prairie dog colony recovery efforts appear sensitive to regularly administered culling. We recommend that colonies that are designated as part of the black‐footed ferret recovery program be protected from population losses from recreational hunting and poisoning.

Tree Cover in the Surrounding Landscape Reduces Burrowing Owl (Athene cunicularia) Occupancy of Black-Tailed Prairie Dog Colonies in South Dakota

Burrowing Owl (Athene cunicularia) population declines have led to the owl's designation as a species of conservation concern in South Dakota. Burrowing Owls nest primarily in black-tailed prairie dog (Cynomys ludovicianus) colonies, but a significant proportion of colonies in South Dakota are not occupied by owls. We studied the influence of landscape-level habitat variables on colony selection by Burrowing Owls. We used call-playback surveys to document presence or absence of Burrowing Owls at 613 prairie dog colonies throughout western and central South Dakota. We used a geographic information system to calculate the percent cover of prairie dog colonies, grassland, cropland, and tree canopy in the surrounding landscape at four buffer sizes. We modeled Burrowing Owl occupancy of prairie dog colonies using logistic regression, and ranked models using Akaike's Information Criterion. All competitive models contained a tree-canopy-cover variable. Increasing tree canopy cover within 800 m and 1200 m of colony centers was associated with decreasing likelihood of occupancy by Burrowing Owls. Grassland, cropland, and prairie dog colony cover variables did not influence occupancy by Burrowing Owls, and these variables did not improve model fit or discrimination. In landscapes where the presence of nesting burrows is not a limiting factor, as in central and western South Dakota, Burrowing Owls occupied colonies based on the absence of trees. Trees provide habitat for avian and mammalian predators and reduce the available foraging area for Burrowing Owls around prairie dog colonies. Management for Burrowing Owls should include conserving prairie dog colonies in landscapes with few trees and preventing the establishment of trees near occupied colonies.

Sylvatic plague management and prairie dogs - a meta-analysis.

Yersinia pestis, a bacterial pathogen that causes sylvatic plague, is present in the prairie dogs (Cynomys spp.) of North America. Epizootics of sylvatic plague through transmission in vectors (fleas) commonly completely extirpate colonies of prairie dogs. Wildlife managers employ a wide variety of insecticidal treatments to suppress plague and conserve prairie dog colonies. I compiled and statistically compared the available literature describing methods of plague control and their relative effectiveness in managing plague outbreaks by using meta-analyses. Natural log response ratios were used to calculate insecticide-induced vector mortality and vaccine-conferred survival increases in prairie dogs in 37 publications. Further, subgroupings were used to explore the most effective of the available vector suppression insecticides and plague suppression vaccines. After accounting for the type of treatment used and the method by which it was applied, I observed plague reduction through use of both insecticides and vaccines. Insecticides resulted in a significant reduction of the abundance of vectors by 91.34% compared to non-treated hosts (p<0.0001). Vaccines improved survival of prairie dog hosts by 4.00% (p<0.0001) compared to control populations. The use of insecticides such as deltamethrin and carbaryl is recommended to stop actively spreading epizootics, and dual antigen oral vaccines to initially suppress outbreaks.

Plague management of prairie dog colonies: degree and duration of deltamethrin flea control

Plague is a flea-borne disease of mammalian hosts. On the grasslands of western North America, plague stifles populations of Cynomys spp. prairie dogs (PDs). To manage plague, PD burrows are treated with 0.05% deltamethrin dust that can suppress flea numbers and plague transmission. Here, we evaluate the degree and duration of deltamethrin flea control with three PD species at six sites across four U.S. states. Data were simultaneously collected at paired plots. Burrows from one randomly assigned member of each pair were treated with deltamethrin; non-treated plots served as experimental baselines. Flea control was strong ≤two months after treatment, remained moderate one year later, and was statistically detectable for up to two years at some sites. Flea abundance was lower in plots with higher rates of deltamethrin application. After burrow treatments, flea abundance increased over time, reaching >one per PD within 255 to 352 days. Nevertheless, annual treatments of burrows with deltamethrin provided PDs with substantial protection against plague. Even so, deltamethrin should be further evaluated and combined with other tools under an integrated approach to plague management. Integrated plague management should help to conserve PDs and species that associate with them, including the endangered black-footed ferret (Mustela nigripes).

Wildlife Refuges Support High Bee Diversity on the Southern Great Plains.

The native prairie of the southern Great Plains has been especially modified by two related forces: conversion of native prairie to agricultural forms of land use and removal of black-tailed prairie dogs (Rodentia: Sciuridae, Cynomys ludovicianus (Ord, 1815)) that act as ecosystem engineers via their burrowing and grazing activities. It is unknown how these changes have affected the native bee community. We surveyed the bee communities in relatively intact native prairie at two National Wildlife Refuges in Texas, quantifying bee community structure as a function of the presence/absence of grazing by prairie dogs. Over a 5-mo sampling period in spring-summer 2013, we found high overall bee diversity (180 species, mostly solitary ground-nesters), with differences detected in diversity between Muleshoe and Buffalo Lake National Wildlife Refuges as well as on and off prairie dog colonies. Although the same three species dominated the bee community at both refuges, most species were represented by relatively few individuals, leading to overall differences in diversity (richness, evenness, and effective number of species) by refuge. Bee diversity differed between sites on and off prairie dog colonies, but in trends that differed by refuge and by index, suggesting that location was more important than prairie dog presence. These results represent a reference fauna against which other regional bee communities in other land-cover types can be compared, but the high spatial heterogeneity we found indicates that detecting effects of landscape change on native bees will be challenging.

Presence of both Active and Inactive Colonies of Prairie Dogs Contributes to Higher Vegetation Heterogeneity at the Landscape Scale

Black-tailed prairie dogs are herbivorous rodents known to have large effects on grassland landscapes in North America. They have considerable impacts on prairie plant communities as the result of repeated clipping of vegetation that can reduce preferred forage species and may indirectly result in increased abundance of disturbance-tolerant species. We investigated plant communities within three different habitat types: Active and inactive prairie dog colonies, and adjacent suitable, but unoccupied, control areas in the Northern Great Plains of Montana, U.S.A. Plant species richness did not vary markedly between the three habitat types. However, plant composition measured as cover of plant life forms (forbs, shrubs, and graminoids), which was further divided into native status (native or introduced), and plant species indicators (plant species associated with a specific habitat) did vary distinctly between the three habitat types. Differences in plant composition between the habitat types suggests black-tailed prairie dog activities result in greater diversity of plant microhabitats at a landscape scale, and prairie dogs are an important component of the overall ecosystem in the Northern Great Plains of North America.

Plague-Positive Mouse Fleas on Mice Before Plague Induced Die-Offs in Black-Tailed and White-Tailed Prairie Dogs.

Plague is a lethal zoonotic disease associated with rodents worldwide. In the western United States, plague outbreaks can decimate prairie dog (Cynomys spp.) colonies. However, it is unclear where the causative agent, Yersinia pestis, of this flea-borne disease is maintained between outbreaks, and what triggers plague-induced prairie dog die-offs. Less susceptible rodent hosts, such as mice, could serve to maintain the bacterium, transport infectious fleas across a colony, or introduce the pathogen to other colonies, possibly facilitating an outbreak. Here, we assess the potential role of two short-lived rodent species, North American deer mice (Peromyscus maniculatus) and Northern grasshopper mice (Onychomys leucogaster) in plague dynamics on prairie dog colonies. We live-trapped short-lived rodents and collected their fleas on black-tailed (Cynomys ludovicianus, Montana and South Dakota), white-tailed (Cynomys leucurus, Utah and Wyoming), and Utah prairie dog colonies (Cynomys parvidens, Utah) annually, from 2013 to 2016. Plague outbreaks occurred on colonies of all three species. In all study areas, deer mouse abundance was high the year before plague-induced prairie dog die-offs, but mouse abundance per colony was not predictive of plague die-offs in prairie dogs. We did not detect Y. pestis DNA in mouse fleas during prairie dog die-offs, but in three cases we found it beforehand. On one white-tailed prairie dog colony, we detected Y. pestis positive fleas on one grasshopper mouse and several prairie dogs live-trapped 10 days later, months before visible declines and plague-confirmed mortality of prairie dogs. On one black-tailed prairie dog colony, we detected Y. pestis positive fleas on two deer mice 3 months before evidence of plague was detected in prairie dogs or their fleas and also well before a plague-induced die-off. These observations of plague positive fleas on mice could represent early spillover events of Y. pestis from prairie dogs or an unknown reservoir, or possible movement of infectious fleas by mice.

Threshold responses of grassland and sagebrush birds to patterns of disturbance created by an ecosystem engineer

Burrowing mammals play a role in rangeland disturbance worldwide, enhancing habitat for certain species while negatively affecting others. However, little is known concerning effects of disturbance spatial pattern on co-occuring fauna. In the North American Great Plains, colonial black-tailed prairie dogs (Cynomys ludovicianus) may enhance habitat for one suite of birds while degrading habitat for others. We examined the influence of prairie dogs on birds in a mosaic grassland–shrubland landscape. We evaluated how birds associated with shortgrass, midgrass, and sagebrush (Artemisia spp.) plant communities respond to spatial pattern of prairie dog disturbance and identified thresholds where abundance changes. We surveyed bird abundance on prairie dog colonies of varying sizes and shapes, across colony edges into undisturbed habitat, and within undisturbed sagebrush in northeastern Wyoming. We modeled species responses to colony presence, distance to colony edge, and total area and edge density of colonies at four spatial scales (100 m, 225 m, 500 m, 1000 m). Sagebrush specialists like Brewer’s sparrow (Spizella breweri) and sage thrasher (Oreoscoptes montanus) were 4.5 times more abundant in undisturbed shrublands. Conversely, the shortgrass-specialist mountain plover (Charadrius montanus) was abundant on colonies but showed a non-linear response to colony edge, increasing in abundance up to 600 m from edges then declining further towards colony cores. While some species may be broadly intolerant to disturbance, disturbance-dependent birds can display a “goldilocks syndrome” relative to disturbance size. As such, management for multiple species of conservation concern can be optimized relative to other goals by identifying thresholds associated with the effect of disturbance.

Trophic Ecology Warrants Multispecies Management in a Grassland Setting: Proposed Species Interactions on Black-tailed Prairie Dog Colonies

On the Ground • Trophic cascades occur when flora and fauna directly and/or indirectly influence co-occurring species populations at different levels of the food chain, and North American temperate grasslands provide an interesting case study to research these relationships. • We briefly define trophic cascades in terrestrial systems and explore the potential for a cascading trophic interaction among grassland-associated swift fox (Vulpes velox), western burrowing owl (Athene cunicularia hypugaea), and mountain plover (Charadrius montanus), three rangeland species of conservation concern, on black-tailed prairie dog (Cynomys ludovicianus) colonies using two US Forest Service data sets. • Historic patterns of occurrence and co-occurrence suggest top-down control governs the spatiotemporal distribution patterns of the three species and may be influenced by habitat fragmentation and management actions. • Managing for interactive, multitrophic communities requires the identification of species interactions and the mechanisms that drive them. • Long-term multispecies occupancy research, combined with hypothesized driving mechanisms and the co-occurrence of associated grassland species, is recommended for addressing these complex interactions moving forward.

Evaluation of Five Pulicides to Suppress Fleas on Black-Tailed Prairie Dogs: Encouraging Long-Term Results with Systemic 0.005% Fipronil.

Plague, a flea-borne disease, hampers efforts to restore populations of black-footed ferrets (Mustela nigripes), which occupy colonies of prairie dogs (Cynomys spp.) in North America. Plague is managed by infusing prairie dog burrows with DeltaDust® 0.05% deltamethrin, a pulicide that kills fleas. Experiments are needed to identify pulicides that can be used in rotation with DeltaDust for integrated plague management. In South Dakota, USA, we tested the efficacy of four pulicide dusts when applied at a rate of 8 g per burrow on colonies of black-tailed prairie dogs (Cynomys ludovicianus): Sevin® 5% carbaryl; Dusta-cide® 6% malathion; Alpine® 0.25% dinotefuran with 95% diatomaceous earth; and Tri-Die® 1% pyrethrum with 40% amorphous silica and 10% piperonyl butoxide. We also tested systemic 0.005% fipronil, which was distributed as ½ cup of laced grain per burrow. We sampled prairie dogs on 3294 occasions and detected 10,041 fleas. Sevin and Dusta-cide suppressed fleas but only for 1 month. Neither Alpine nor Tri-Die had any noticeable, consistent effect on fleas. Fipronil suppressed fleas by 97-100% for 3 months. The residual effect of fipronil persisted for ∼12 months. Efficacy of fipronil seems comparable with DeltaDust, which exhibited a residual effect for ∼10 months in prior studies. Continued research is needed to optimize fipronil treatments for plague management on prairie dog colonies.