Prairie Dog Burrows Research Articles

Abundance estimates of Gunnison's prairie dogs compared to the number of active burrows

AbstractReliable estimates of prairie dog (Cynomys spp.) population size and distribution are critical for assessing the status of prairie dogs and for selecting sites to reintroduce black‐footed ferrets (Mustela nigripes). The density of active prairie dog burrows has commonly been used as an index of prairie dog abundance. Indices derived from active burrow counts were developed for black‐tailed (C. ludovicianus) and white‐tailed (C. leucurus) prairie dogs, but their efficacy has not been evaluated for all prairie dog species and studies affirming their validity with robust abundance estimators are few. We indexed or estimated the abundance of Gunnison's prairie dogs (C. gunnisoni) in the Aubrey Valley, Arizona, USA, in 2006 at 2 different time periods using 4 different methods—maximum above ground counts (MAGC), minimum number known alive (MNKA), capture‐mark‐recapture (CMR), and mark‐resight—and compared these estimates to active burrow counts in 2005 and 2006. We found no positive relationship between active burrow counts and any abundance estimators. Mark‐resight estimates of abundance were greater than the MNKA and were positively correlated with both the MNKA (r2 = 0.30) and CMR estimates (r2 = 0.49). Both CMR estimates and MAGC were typically below the MNKA and therefore biased low. Our results indicated that more rigorous estimation methods may be necessary to accurately estimate prairie dog abundance and assess habitat quality for ferret conservation.

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.

LETHAL EFFECTS ON FLEA LARVAE OF FIPRONIL IN HOST FECES: POTENTIAL BENEFITS FOR PLAGUE MITIGATION.

Plague, caused by the bacterium Yersinia pestis, is a zoonotic disease of mammalian hosts and flea vectors. Fipronil baits have been used to suppress adult fleas for plague mitigation. The degree and duration of flea control may increase if fipronil also kills other stages in the flea life cycle. We fed grain treated with 0.005% fipronil by weight, or nontreated grain, to black-tailed prairie dogs (Cynomys ludovicianus), which excrete fipronil and metabolites in their feces after consuming fipronil in their diet. We presented prairie dog feces to 331 larval Oropsylla montana (Siphonaptera: Ceratophyllidae). When exposed to feces lacking fipronil or metabolites, 84% of larvae survived for 24 h. In contrast, survival declined to 42% for larvae contacting feces from fipronil-treated prairie dogs. Just 7% of larvae consuming feces from fipronil-treated prairie dogs survived. Fipronil and metabolites may persist in host feces for several months or longer in prairie dog burrows where flea larvae dwell and forage. The lethal effects of fipronil on adult and larval fleas (and perhaps other life stages) may help to explain why fipronil baits are capable of suppressing fleas on prairie dogs for ≥12 mo.

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.

A Prototype Insecticide Applicator and Quality Control Monitoring for Plague Management on Prairie Dog Colonies

ABSTRACTPlague causes declines in native wildlife populations including those of prairie dogs (Cynomys sp.) and endangered black‐footed ferrets (Mustela nigripes). The infusion of insecticides into prairie dog burrows is a vector control method regularly used to suppress or prevent plague transmission by fleas. Detailed methods on how insecticide application equipment (dusters) is calibrated or how the quality of application is monitored are not regularly reported. We describe a new prototype duster and compare its performance to commercially available equipment using quality‐control monitoring procedures. We infused 0.05% deltamethrin (dust) into burrows of Gunnison's and black‐tailed prairie dogs (C. gunnisoni, C. ludovicianus) in Colorado in 2014–2017. The prototype and commercial dusters distributed a similar amount of dust ( = 5.39 and 5.29 g/burrow, respectively; t(797) = −0.83, P = 0.4). However, the prototype dusters required less operation time to dispense dust than the commercial dusters ( = 1.0 sec vs. 7.69 sec/burrow; t(481) = 49.2, P ≤ 0.001). If we applied a standard operating time of 5 sec to all commercially available units, 60% (20 of 34) would fail to dispense ≥4 g of dust. The prototype dusters were more consistent in their dust output, with all units (12 of 12) dispensing ≥4 g of dust with an operation time of only 1 sec. Controlled and accurate application of insecticide is difficult to achieve if quality‐control monitoring and equipment calibration are not conducted. The efficacy of vector control is likely only as effective as the quality and precision of the application of the insecticide itself. When evaluating plague management outcomes, it is important to consider if some observed limitations of efficacy are caused by the failure of the management tool or the failure of managers to effectively use the tool. Future work to calibrate the prototype dusters to dispense larger target doses and performance testing with other insecticide formulations is needed. Additional modifications to adapt the prototype dusters for use on ATV‐mounted platforms may increase the utility of the equipment. © 2021 The Wildlife Society.

Possible Litter of Seven Wild Black-Footed Ferret Kits

Endangered black-footed ferrets (BFFs, Mustela nigripes) specialize on prairie dogs (Cynomys spp.) for prey and use prairie dog burrows for shelter. In the wild, female BFFs produce 2–3 kits on average. Litters of 6 have been observed. At the Conata Basin, South Dakota, we observed an adult female BFF, named F05–183, with 7 kits. Data on space use by neighboring female BFFs suggest that F05–183 produced all 7 kits; alternative explanations are discussed. To our knowledge, this is the largest recorded litter count for wild-born BFFs.

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.

RESISTANCE TO DELTAMETHRIN IN PRAIRIE DOG ( CYNOMYS LUDOVICIANUS) FLEAS IN THE FIELD AND IN THE LABORATORY.

Sylvatic plague poses a substantial risk to black-tailed prairie dogs ( Cynomys ludovicianus) and their obligate predator, the black-footed ferret ( Mustela nigripes). The effects of plague on prairie dogs and ferrets are mitigated using a deltamethrin pulicide dust that reduces the spread of plague by killing fleas, the vector for the plague bacterium. In portions of Conata Basin, Buffalo Gap National Grassland, and Badlands National Park, South Dakota, US, 0.05% deltamethrin has been infused into prairie dog burrows on an annual basis since 2005. We aimed to determine if fleas ( Oropsylla hirsuta) in portions of the Conata Basin and Badlands National Park have evolved resistance to deltamethrin. We assessed flea prevalence, obtained by combing prairie dogs for fleas, as an indirect measure of resistance. Dusting was ineffective in two colonies treated with deltamethrin for >8 yr; flea prevalence rebounded within 1 mo of dusting. We used a bioassay that exposed fleas to deltamethrin to directly evaluate resistance. Fleas from colonies with >8 yr of exposure to deltamethrin exhibited survival rates that were 15% to 83% higher than fleas from sites that had never been dusted. All fleas were paralyzed or dead after 55 min. After removal from deltamethrin, 30% of fleas from the dusted colonies recovered, compared with 1% of fleas from the not-dusted sites. Thus, deltamethrin paralyzed fleas from colonies with long-term exposure to deltamethrin, but a substantial number of those fleas was resistant and recovered. Flea collections from live-trapped prairie dogs in Thunder Basin National Grassland, Wyoming, US, suggest that, in some cases, fleas might begin to develop a moderate level of resistance to deltamethrin after 5-6 yr of annual treatments. Restoration of black-footed ferrets and prairie dogs will rely on an adaptive, integrative approach to plague management, for instance involving the use of vaccines and rotating applications of insecticidal products with different active ingredients.

Plague in a Colony of Gunnison's Prairie Dogs ( Cynomys gunnisoni) Despite Three Years of Infusions of Burrows with 0.05% Deltamethrin to Kill Fleas.

At Valles Caldera National Preserve in New Mexico, US, infusing Gunnison's prairie dog ( Cynomys gunnisoni) burrows with an insecticide dust containing 0.05% deltamethrin killed fleas which transmit bubonic plague. The reduction in the number of fleas per prairie dog was significant and dramatic immediately after infusions, with a suggestion that the reduction persisted for as long as 12 mo. Despite the lower flea counts, however, a plague epizootic killed >95% of prairie dogs after 3 yr of infusions (once per year). More research is necessary for a better understanding of the efficacy of insecticide dusts at lowering flea counts and protecting prairie dogs from plague.

Factors Influencing Burrowing Owl Abundance in Prairie Dog Colonies on the Southern High Plains of Texas

Large numbers of Western Burrowing Owls (Athene cunicularia hypugaea) nest in black-tailed prairie dog (Cynomys ludovicianus) colonies in the southern high plains of Texas. Because the Western Burrowing Owl is a species of concern with an uncertain future due to widespread extirpation of prairie dogs, we examined the roles of prairie dog colony size, burrow density, proxies of prey availability, and vegetative composition and structure on owl abundance and reproductive rate. The number of nesting Burrowing Owl pairs was positively correlated to colony area (r2 = 0.550, P = 0.006) and to number of prairie dog burrows in a colony (r2 = 0.733, P = 0.0230). Burrowing Owl numbers and reproductive rate (maximum number of young seen per successful pair) were not related to our measures of vegetative composition and structure in prairie dog colonies, nor to indices of prey availability.

Detections of Yersinia pestis East of the Known Distribution of Active Plague in the United States.

We examined fleas collected from black-tailed prairie dog (Cynomys ludovicianus) burrows from 2009 through 2011 in five national park units east of the known distribution of active plague across the northern Great Plains for the presence of Yersinia pestis. Across all national park units, Oropsylla tuberculata and Oropsylla hirsuta were the most common fleas collected from prairie dog burrows, 42.4% and 56.9%, respectively, of the 3964 fleas collected from burrow swabbing. Using a nested PCR assay, we detected 200 Y. pestis-positive fleas from 3117 assays. In total, 6.4% of assayed fleas were Y. pestis positive and 13.9% of prairie dog burrows swabbed contained Y. pestis-positive fleas. Evidence of the presence of Y. pestis was observed at all national park units except Devils Tower National Monument in Wyoming. We detected the presence of Y. pestis without large die-offs, i.e., enzootic sylvatic plague, east of the known distribution of active plague and near the eastern edge of the present distribution of black-tailed prairie dogs. This study, in combination with previous work suggests that sylvatic plague likely occurs across the range of black-tailed prairie dogs and should now be treated as endemic across this range.

Plague bacterium as a transformer species in prairie dogs and the grasslands of western North America.

Invasive transformer species change the character, condition, form, or nature of ecosystems and deserve considerable attention from conservation scientists. We applied the transformer species concept to the plague bacterium Yersinia pestis in western North America, where the pathogen was introduced around 1900. Y. pestis transforms grassland ecosystems by severely depleting the abundance of prairie dogs (Cynomys spp.) and thereby causing declines in native species abundance and diversity, including threatened and endangered species; altering food web connections; altering the import and export of nutrients; causing a loss of ecosystem resilience to encroaching invasive plants; and modifying prairie dog burrows. Y. pestis poses an important challenge to conservation biologists because it causes trophic-level perturbations that affect the stability of ecosystems. Unfortunately, understanding of the effects of Y. pestis on ecosystems is rudimentary, highlighting an acute need for continued research.

Investigation of Factors Affecting Black-Footed Ferret Litter Size

AbstractUnderstanding factors that influence recruitment can improve wildlife conservation. Endangered black-footed ferrets (Mustela nigripes) rely on prairie dogs (Cynomys spp.) for food and on prairie dog burrows for shelter. We hypothesized that younger female ferrets with greater densities of prairie dogs in their core use area and fewer adult ferrets in their respective prairie dog colony, would produce more kits due to age-dependent productivity, increased food resources, and decreased competition. We used generalized linear mixed-effects regression and Akaike's information criterion adjusted for sample size (AICc) to rank models relating adult female black-footed ferret litter size (range 1–7 kits, n = 24 litters) to female age, core area density of prairie dogs, and adult ferret densities from 3 sites in the USA, 2005–2008. We included year and site as random effects in all models. We observed great model uncertainty; the null model was most supported and received 44% of model weight (w). The next...

Space use, Resource Selection and Territoriality of Black‐Footed Ferrets: Implications for Reserve Design

Insight into the spatial ecology of predators might help biologists to design wildlife reserves that maximize conservation success. We investigated the spatial ecology of endangered black‐footed ferrets Mustela nigripes during the post‐breeding seasons (June–October) of 2007 and 2008 on a 452‐ha colony of black‐tailed prairie dogs Cynomys ludovicianus in South Dakota, USA. Ferrets of both sexes frequently used areas with an abundance of active openings to prairie dog burrows, suggesting a positive response to refuge and prey. Densities of active burrow openings were similar in areas of same‐sex overlap and areas of exclusive space use, which might suggest limited defense of resources by ferrets. However, this result could be expected in our study because much of the study colony contained high densities of active burrow openings. Same‐sex home ranges overlapped in area, but the intensity of space use overlap was low. For male ferrets with overlapping home ranges, both males tended to spend low amounts of time in areas of overlap. In contrast, for pairs of overlapping female home ranges, one female frequently used areas of overlap while the second apparently avoided them, suggesting a dominance hierarchy of some sort. Core areas were essentially exclusive. Our data are consistent with the hypothesis of intrasexual territoriality by ferrets in habitats of high quality, which would limit the number of ferrets a habitat supports. Where wildlife managers aim to maximize densities of free‐ranging ferrets, it might be beneficial to create reserves that 1) provide each ferret with sufficient prey and refuge, 2) reduce social conflict and competition for space, and 3) facilitate dispersal.

Western Burrowing Owls (Athene cunicularia hypugaea) Eavesdrop on Alarm Calls of Black‐Tailed Prairie Dogs (Cynomys ludovicianus)

AbstractAnimals sharing a common habitat can indirectly receive information about their environment by observing information exchanges between other animals, a process known as eavesdropping. Animals that use an auditory alarm calling system are an important indirect information source for eavesdropping individuals in their environments. We investigated whether Western burrowing owls (Athene cunicularia hypugaea) nesting on black‐tailed prairie dog (Cynomys ludovicianus) colonies responded to broadcasts of prairie dog alarm calls. Western burrowing owls are closely associated with black‐tailed prairie dogs in Colorado and neighboring states on the Great Plains of the United States. Prairie dog burrows in active colonies can serve as nesting sites for Western burrowing owls, and prairie dogs may act as an alternative prey source for predators, potentially decreasing the burrowing owls' risk of predation through the dilution effect. Burrowing owls nesting on prairie dog colonies may also eavesdrop on prairie dog alarm calls, enhancing their survival and nesting success on prairie dog colonies. We performed broadcast experiments with three different sounds: a prairie dog alarm call, a biological control (cattle mooing), and a non‐biological control (an airplane engine), and characterized burrowing owl responses as either alert or relaxed. For each sound stimulus, we recorded the time to first alert response to broadcast sounds (latency) and also how frequently the target burrowing owl exhibited an alert response within the first ten seconds of the broadcast (intensity). Burrowing owls reacted more quickly to the prairie dog alarm than to the biological control. They significantly increased the intensity of alert behaviors in response to broadcasts of the alarm, but did not show an increased reaction to either the biological or the non‐biological control. Our results suggest that burrowing owls nesting on prairie dog colonies eavesdrop on, and increase their alert behaviors in response to, prairie dog alarm calls.

Black-Footed Ferret Digging Activity in Summer

Black-footed ferrets (Mustela nigripes) excavate soil from prairie dog (Cynomys spp.) burrows, thereby creating characteristic soil deposits at burrow openings. These soil deposits have been observed only rarely in summer. We monitored adult ferrets during June–October of the years 2007 and 2008 on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We located and identified ferret excavations during nighttime spotlight surveys for ferrets and daytime sampling of prairie dog burrow openings around locations where ferrets were located via spotlight. We accumulated 48 observations of in-process or recently completed ferret excavations during spotlight surveys (21 in 2007, 27 in 2008) and located 51 diggings during daytime burrow sampling (25 in 2007, 26 in 2008). We located diggings during 5.5% of spotlight observations, most frequently in July–August. These results collectively suggest ferrets may frequently excavate soil in summer, because prairie dogs frequently use soil to plug burrow openings and tunnels in defense against ferrets. Prairie dogs might frequently destroy soil deposits left by ferrets during summer, thereby reducing detection of diggings by biologists.

Use of Multi-Opening Burrow Systems by Black-Footed Ferrets

Multi-opening burrow systems constructed by prairie dogs (Cynomys) ostensibly provide escape routes when prairie dogs are pursued by predators capable of entering the burrows, such as black-footed ferrets (Mustela nigripes), or by predators that can rapidly dig into the tunnels, such as American badgers (Taxidea taxus). Because badgers also prey on ferrets, ferrets might similarly benefit from multi-opening burrow systems. Using an air blower, white-tailed prairie dog (Cynomys leucurus) burrow openings were tested for connectivity on plots occupied by black-footed ferrets and on randomly selected plots in Wyoming. Significantly more connected openings were found on ferret-occupied plots than on random plots. Connected openings might be due to modifications by ferrets in response to plugging by prairie dogs, due to selection by ferrets for complex systems with multiple openings that are already unobstructed, or simply due to ferrets lingering at kill sites that were multi-opening systems selected by their prairie dog prey.

Importance of Lunar and Temporal Conditions for Spotlight Surveys of Adult Black-Footed Ferrets

Black-footed ferrets (Mustela nigripes) spend most daylight hours underground in prairie dog (Cynomys) burrows and exhibit aboveground movements primarily at night. Moonlight can influence the activity patterns of ferrets and, consequently, might influence the efficiency of spotlight surveys used by biologists to monitor ferret populations. We related detection of adult ferrets during postbreeding spotlight surveys to lunar and temporal conditions. We most frequently located ferrets during surveys in which the moon breached the horizon. The data suggested intersexual differences in response to moonlight. We located male ferrets most frequently during nights with greater moon illumination, but we did not detect a correlation between moon illumination and spotlight detection of female ferrets. In general, moonlight could facilitate aboveground navigation by ferrets. However, it seems activity under bright moonlight could be costly for female ferrets while they raise young. Detection of ferrets also varied among months. We detected female ferrets most frequently in August–September, when mothers increase hunting efforts to acquire prey for growing offspring (kits). Detection of adult female ferrets declined in October, when kits were likely independent of their mother. We located male ferrets most frequently in September–October, when males might increase activity to monitor female ferrets and male competitors. Consideration of lunar and temporal influences and standardization of postbreeding surveys could enhance site-specific assessment of reintroduction success and across-site assessment of species recoveiy progress. We suggest that postbreeding surveys for ferrets should be enhanced by concentrating efforts in August–September during moonlit nights when the moon is above the horizon.

Resource Selection Models are Useful in Predicting Fine-Scale Distributions of Black-Footed Ferrets in Prairie Dog Colonies

Wildlife-habitat relationships are often conceptualized as resource selection functions (RSFs)—models increasingly used to estimate species distributions and prioritize habitat conservation. We evaluated the predictive capabilities of 2 black-footed ferret (Mustela nigripes) RSFs developed on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We used the RSFs to project the relative probability of occurrence of ferrets throughout an adjacent 227-ha colony. We evaluated performance of the RSFs using ferret space use data collected via postbreeding spotlight surveys June–October 2005–2006. In home ranges and core areas, ferrets selected the predicted “very high” and “high” occurrence categories of both RSFs. Count metrics also suggested selection of these categories; for each model in each year, approximately 81% of ferret locations occurred in areas of very high or high predicted occurrence. These results suggest usefulness of the RSFs in estimating the distribution of ferrets throughout a black-tailed prairie dog colony. The RSFs provide a fine-scale habitat assessment for ferrets that can be used to prioritize releases of ferrets and habitat restoration for prairie dogs and ferrets. A method to quickly inventory the distribution of prairie dog burrow openings would greatly facilitate application of the RSFs.

Black-Footed Ferrets and Recreational Shooting Influence the Attributes of Black-Tailed Prairie Dog Burrows

ABSTRACT. Black-tailed prairie dogs (Cynomys ludovicianus) plug burrows occupied by black-footed ferrets (Mustela nigripes), and they also plug burrows to entomb dead prairie dogs. We further evaluated these phenomena by sampling connectivity and plugging of burrow openings on prairie dog colonies occupied by ferrets, colonies where recreational shooting was allowed, and colonies with neither shooting nor ferrets. We counted burrow openings on line surveys and within plots, classified surface plugging, and used an air blower to examine subsurface connectivity. Colonies with ferrets had lower densities of openings, fewer connected openings (suggesting increased subsurface plugging), and more surface plugs compared to colonies with no known ferrets. Colonies with recreational shooting had the lowest densities of burrow openings, and line-survey data suggested colonies with shooting had intermediate rates of surface plugging. The extent of surface and subsurface plugging could have consequences for the prair...