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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. [ABSTRACT FROM AUTHOR]

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 night-time predations and therefore underestimate numbers of successful attacks, suggest that a single predatory individual can have a sudden, devastating effect on a prey species. [ABSTRACT FROM AUTHOR]

Dispersal in mammals is typically male-biased and occurs primarily in sexually immature individuals. These dispersal characteristics are especially true for ground-dwelling sciurids, such as black-tailed prairie dogs (Cynomys ludovicianus), that have polygynous breeding systems, with dispersing males and philopatric females. Prairie dogs are small, colonial rodents found in patches throughout the Great Plains of North America. Previous literature reports that females exist in philopatric units called coteries, typically with one unrelated breeding male. Yearling males disperse from their natal coterie in order to form their own coteries. We observed 1450 prairie dogs over 3 consecutive years in one colony near the northern limit of this species' range, in Grasslands National Park, Saskatchewan. We found that female dispersal occurred at higher rates than previously reported in the literature. We found no difference between the rate of intracolony dispersal for males and females in our study population. Also, we observed that the majority (14/21) of the dispersing females had recently experienced reproductive failure. We suggest that these females dispersed to increase their potential fitness by attempting reproduction in a new territory. This finding is the first instance of a ground-dwelling sciurid demonstrating female-biased breeding dispersal and suggests that factors influencing dispersal are more complicated than previously reported for black-tailed prairie dogs. [ABSTRACT FROM AUTHOR]

Understanding 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 best-supported model included ferret density only (▵ AICc = 1.55, w = 0.20). Ferret density may not have been great enough to negatively affect prey acquisition and litter sizes. Mean litter size did not vary among female ages, but inference was limited because only one individual was >3 years old (x = 2.13 years, SD = 0.99). All adult females produced kits, suggesting that the observed minimum prairie dog density in ferret core use areas (12.3 individuals · ha-1) was above a threshold of minimal prey abundance for reproduction. Our findings support previous selections of rein traduction sites as those meeting minimum resource needs of individual ferrets for reproduction. Future selections of rein traduction sites may become more difficult if the number of areas with the minimum necessary prajirie dog density decreases due to disease and reductions in habitat availability. [ABSTRACT FROM AUTHOR]

American bison (Bison bison L.) preferentially use black-tailed prairie dog (Cynomys ludovicianus L.) colonies over uncolonized range in the mixed-grass prairie of North America. To assess bison use of prairie dog colonies in a different ecosystem, the shortgrass steppe, this study was conducted at the Vermejo Park Ranch, New Mexico. Driving surveys were conducted in summer 2007 to determine the number of bison on and off prairie dog colonies in 2 pastures. Prairie dogs occupied 25.5% and 48.5% of the 2 pastures surveyed. Bison of both sexes used prairie dog colonies more than expected compared to a scenario of bison using colonies based on colony availability (P < 0.001). With the exception of bulls in one pasture, bison observed off-colony were more likely to be grazing than bison observed oncolony (P < 0.04). When selection of prairie dog colonies was assessed for only those bison observed grazing, bulls in both pastures and cows in one pasture used prairie dog colonies more than expected based on availability (P ⩽ 0.001). Forage quality was superior on prairie dog colonies, with crude protein higher (P < 0.001) and acid detergent fiber lower (P < 0.001) in blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths) collected on-colony than offcolony. Further studies under a variety of conditions are still needed, but selection for prairie dog colonies by bison at Vermejo, combined with findings from previous studies, suggests that during the growing season, bison and cattle (Bos taurus L.) might select prairie dog colonies over uncolonized range in both the northern and southern extents of North American grasslands. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 recovery 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. [ABSTRACT FROM AUTHOR]

Black-footed ferrets (Mustela nigripes) are among the most endangered animals in North America. Reintroductions of captive-born ferrets onto prairie dog (Cynomys spp.) colonies are crucial to the conservation of the species. In September 2007, captive-born ferrets were released on a black-tailed prairie dog (Cynomys ludovicianus) colony at the Vermejo Park Ranch, New Mexico. Ferret kits experimentally released in areas of comparatively low and high prairie dog burrow densities were located via spotlight surveys. Some maturing ferret kits were subsequently translocated to areas of low and high burrow densities on nearby prairie dog colonies. For 2 months, fine-scale habitat use was quantified by mapping all burrow openings within a 30-m radius of each ferret location. Spatial statistics accounted for autocorrelation in the burrow densities in areas used by ferrets. It was hypothesized that ferrets would select areas of high burrow densities within colonies; however, burrow densities in areas used by ferrets were generally similar to the available burrow densities. Because ferrets used areas with burrow densities similar to densities available at the colony level and because of the potential energetic benefits for ferrets using areas with high burrow densities, releasing ferrets on colonies with high burrow densities might increase reintroduction success. [ABSTRACT FROM AUTHOR]

Intensive radio-tracking during August-December enabled us to collect detailed information on digging behaviors of a small sample of black-footed ferrets (Mustela nigripes) occupying colonies of white-tailed prairie dogs (Cynomys leucurus). A sample of 33 prairie dogs, also radio-tagged, progressively ceased aboveground activity during late summer and fall, presumably as they descended into burrows to hibernate. Most of the time ferrets spent digging was in November-December when >95% of the radio-tagged prairie dogs were inactive, suggesting that digging was primarily to excavate hibernating prey. Although 43.9% of the burrow openings were estimated to be in large mounds, which are common on colonies of white-tailed prairie dogs, all of a sample of 17 deposits of soil (diggings) made by ferrets were excavated at small mounds or nonmounded openings. The average duration of 23 nocturnal sessions of digging by ferrets was 112.2 minutes. A digging session consisted of multiple bouts of soil movement typically lasting about 5 min, and sessions were separated by pauses above- or belowground lasting several minutes. Bouts of moving soil from a burrow involved round-trips of 12.5-30.3 s to remove an average of 35 cm3 of soil per trip. These digging bouts are energetically costly for ferrets. One female moved 16.8 kg of soil an estimated 3.3 m during bouts having a cumulative duration of 178 minutes, removing a soil plug estimated to be 178 cm long. Increasing evidence suggests that some behaviors of ferrets and prairie dogs are coevolutionary responses between this highly specialized predator and its prairie dog prey. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Once feared to be extinct, black-footed ferrets (Mustela nigripes) were rediscovered near Meeteetse, Wyoming, in 1981, resulting in renewed conservation and research efforts for this highly endangered species. A need for information directly useful to recovery has motivated much monitoring of ferrets since that time, but field activities have enabled collection of data relevant to broader biological themes. This special feature is placed in a context of similar books and proceedings devoted to ferret biology and conservation. Articles include general observations on ferrets, modeling of potential impacts of ferrets on prairie dogs (Cynomys spp.), discussions on relationships of ferrets to prairie dog habitats at several spatial scales (from individual burrows to patches of burrow systems) and a general treatise on the status of black-footed ferret recovery. [ABSTRACT FROM AUTHOR]

We describe observations of black-tailed prairie dogs (Cynomys ludovicianus) emerging aboveground at night, apparently in response to wild-born and captive-born black-footed ferrets (Mustela nigripes) in South Dakota and New Mexico, respectively. We also discuss other similar observations accumulated on black-tailed prairie dog colonies as well as observations of white-tailed prairie dogs (Cynomys leucurus) making nighttime movements, apparently in response to pre-reintroduction ferrets in Wyoming. Our observations suggest that, in addition to documented daytime defenses against ferrets, prairie dogs reduce vulnerability to predation by ferrets by using evasive movements at night. [ABSTRACT FROM AUTHOR]