Prairie Dog Burrows Research Articles

Treatment of black-tailed prairie dog burrows with deltamethrin to control fleas (Insecta: Siphonaptera) and plague.

Burrows within black-tailed prairie dog (Cynomys ludovicianus) colonies on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, were dusted with deltamethrin insecticide to reduce flea (Insecta: Siphonaptera) abundance. Flea populations were monitored pre- and posttreatment by combing prairie dogs and collecting fleas from burrows. A single application of deltamethrin significantly reduced populations of the plague vector Oropsylla hirsuta, and other flea species on prairie dogs and in prairie dog burrows for at least 84 d. A plague epizootic on the Rocky Mountain Arsenal National Wildlife Refuge caused high mortality of prairie dogs on some untreated colonies, but did not appear to affect nearby colonies dusted with deltamethrin.

Effects of grazing practices and fossorial rodents on a winter avian community in Chihuahua, Mexico

Chihuahuan Desert grasslands are important wintering grounds for grassland and shrub-adapted birds. Many species belonging to these assemblages are currently exhibiting population declines. One area recognized for its importance to biological diversity, including grassland birds, is the Janos-Nuevo Casas Grandes black-tailed prairie dog ( Cynomys ludovicianus) complex in northwestern Chihuahua, Mexico, an area containing 58 colonies with 30,000 ha of prairie dogs. This is one of the largest remaining prairie dog complexes and the only intact complex in the Chihuahuan Desert. In its current condition, a large percentage of this complex is of reduced value to wildlife. Overgrazing on communal (ejido) lands has resulted in areas being comprised of annual grasses and forbs. The density of active prairie dog burrows and banner-tailed kangaroo rat ( Dipodomys spectabilis) mounds as well as avian diversity and abundance were lower on ejido lands than an adjacent private ranchland with and without prairie dogs. Few avian species used overgrazed portions of the prairie dog colony. Community similarity among plot types was low due to different management practices and differences on and off colony. To retain, and in many instances restore the biological diversity of this important region it is essential to work with local ejidos on grazing management.

Landscape effects on black-tailed prairie dog colonies

Black-tailed prairie dogs (Cynomys ludovicianus) increasingly compete for available habitat with human development in the Colorado Front Range. Because the effects of increased urbanization on prairie dog colonies are unknown, we studied how landscape context affects prairie dog density in Boulder County, Colorado, USA. We used burrow density as a proxy for prairie dog density because these variables were correlated at our study sites ( r=0.60). Using remotely sensed data and a GIS, we quantified percent urbanization, road density, and the percentage of other prairie dog colonies in the surrounding landscape at 200, 1000, and 2000 m from the perimeter of 22 prairie dog colonies, and compared burrow density with each landscape variable at each scale. We also calculated Akaike's information criterion (AIC) to determine the most parsimonious models predicting burrow density. Ranges of burrow densities and prairie dog densities in Boulder County were higher than in other studies using similar methodology. Within Boulder County, burrow density was significantly higher in colonies surrounded by greater density of roads. The degree to which prairie dog colonies were immediately surrounded by unsuitable habitat, i.e. the “boundedness” of the colony, was negatively correlated with colony area and positively correlated with burrow density. A model based on boundedness, the density of roads at the 2000 m scale, and the amount of prairie dog colonies at the 200 m scale explained 73% of the variance in prairie dog burrow density. However, a non-linear model including boundedness and the squared term of road density at the 2000 m scale had the lowest AIC value of all linear and non-linear models, indicating a possible threshold effect of urbanization on prairie dog density. Urbanization may have several implications for prairie dog persistence. Increased prairie dog density in urbanized landscapes may be related to the Refuge effect, i.e. decreased predator abundance. If higher prairie dog density increases competition for available resources, habitat quality may decline leading to population decline in highly urbanized landscapes. Furthermore, if dispersal is reduced in urbanized landscapes, then these colonies may not be recolonized after local extirpation from plague epizootics. Alternatively, urbanized colonies may be effectively isolated from plague vectors and reservoir hosts, which could result in a lower frequency of plague epizootics when compared to non-urbanized colonies.

Detection of novel Bartonella strains and Yersinia pestis in prairie dogs and their fleas (Siphonaptera: Ceratophyllidae and Pulicidae) using multiplex polymerase chain reaction.

We developed a multiplex polymerase chain reaction (PCR) assay that simultaneously detects three types of flea-associated microorganisms. Targets for the assay were sequences encoding portions of the gltA, a 17-kDa antigen, and pla genes of Bartonella spp. Strong et al., Rickettsia spp. da Rocha-Lima, and Yersinia pestis Yersin, respectively. A total of 260 flea samples containing bloodmeal remnants were analyzed from fleas collected from abandoned prairie dog (Cynomys ludovicianus) burrows at the site of an active plague epizootic in Jefferson County, CO. Results indicated that 34 (13.1%) fleas were positive for Bartonella spp., 0 (0%) were positive for Rickettsia spp., and 120 (46.2%) were positive for Y. pestis. Twenty-three (8.8%) of these fleas were coinfected with Bartonella spp. and Y. pestis. A second group of 295 bloodmeal-containing fleas was collected and analyzed from abandoned burrows in Logan County, CO, where a prairie dog die-off had occurred 2-4 mo before the time of sampling. Of these 295 fleas, 7 (2.4%) were positive for Bartonella spp., 0 (0%) were positive for Rickettsia spp., and 46 (15.6%) were positive for Y. pestis. Coinfections were not observed in fleas from the Logan County epizootic site. The multiplex PCR also was used to identify Y. pestis and Bartonella in prairie dog blood and tissues. This report represents the first identification of Bartonella from prairie dogs and their fleas. Prairie dog fleas were tested with PCR, and the Bartonella PCR amplicons produced were sequenced and found to be closely related to similar sequences amplified from Bartonella that had been isolated from prairie dog blood samples. Phylogenetic analyses indicate that the sequences of bartonellae from prairie dogs and prairie dog fleas cluster tightly within a clade that is distinct from those containing other known Bartonella genotypes.

Home range and habitat use of the kit fox (Vulpes macrotis) in a prairie dog (Cynomys ludovicianus) complex

AbstractThe largest remaining black‐tailed prairie dog Cynomys ludovicianus towns in North America are in Mexico, where they coexist with the kit fox Vulpes macrotis, providing a unique opportunity to study the relationship between these threatened species. We hypothesized that the presence of prairie dogs would positively affect the kit fox population in our study area in north‐western Mexico, and that these influences would be manifest in home‐range size, density and habitat selection. We estimated fox densities fluctuating from 0.32/km2 to 0.8/km2, and radio‐telemetry revealed minimum convex polygon home ranges averaging 11 km2. These values are within the bounds of estimates from study sites elsewhere. Foxes used mesquite scrub less than expected, but grassland more than expected in relation to availability. Other habitats, including prairie dog towns, were used at random. Most (65.1% of 43) fox dens were in grassland, and were enlarged kangaroo rat Dipodomys spp. (34.9%) or prairie dog (34.9%) burrows. That kit foxes seemed to select grasslands rather than prairie dog towns was unexpected, particularly as prairie dogs are known to be a major component of kit fox diet. Foxes may reduce the amount of time they spend in prairie dog towns to avoid coyotes, which can be responsible for significant swift fox mortality. In our study area, coyotes were more active in prairie dog towns than in the grassland, where they were regularly shot. However, grassland used by kit foxes is a short‐lived product of prairie dog poisoning, which is quickly invaded by scrub, a habitat favoured by coyotes. We conclude that kit fox conservation initiatives in north‐western Mexico should be closely linked to conservation of the prairie dog ecosystem.

Correlations between Burrowing Owl and Black-Tailed Prairie Dog Declines: A 7-Year Analysis

Concern over the status of species associated with prairie dog colonies has increased with the recent proposed listing of black-tailed prairie dogs (Cynomys ludovicianus). We monitored burrowing owl (Athene cunicularia) populations and prairie dog densities in 17 black-tailed prairie dog colonies in the Nebraska panhandle between 1990 and 1996. All prairie dog colonies were controlled at least once during the study. We observed a 63% decline in nesting pairs of burrowing owls and significant declines in burrow densities. Results indicated a time lag in owl response to changes in active burrow densities. However, in the later years of the study when burrow densities were lowest, owl numbers were positively correlated with the density of active burrows in the same years, indicating active burrows may become more important as burrow density declines. We also monitored fledging success of burrowing owls for 398 nesting attempts over 5 years (1989-93) for a larger set of colonies that included the 17 used in the owl and prairie dog monitoring. Differences in mean fledging success among colonies each year (colony effect) explained most of the variation in fledging success among nesting owls. Vulnerability to badger (Taxidea taxus) predation may in part explain differences in fledging success among colonies; badger predation on owl nests was lower when densities of active prairie dog burrows were high. Efforts are needed to ensure preservation of black-tailed prairie dog colonies for burrowing owls and other species associated with this prairie ecosystem, and to better monitor changes in burrowing owl and prairie dog populations.

Late Pleistocene glacial geomorphology and environment of the Hand Hills region and southern Alberta, related to Middle Wisconsin fossil prairie dog sites

Ichnofossils (burrow casts) and fossils from an extinct form of prairie dog, Cynomys niobrarius churcherii, in the Hand Hills of south-central Alberta, have provided an important Late Pleistocene stratigraphic marker. The marker fossils provide relative and chronostratigraphic (radiocarbon) ages for nonglacial, periglacial, glacial, and glaciotectonic events and environments in the region. The high-elevation, hilltop position of the fossil sites (~200 m above the surrounding plains) permits reliable extrapolations of glacial environments to the surrounding region. The burrow casts were preserved by infilling from surrounding and overlying sediments through processes of inwashing and animal activity. Three thousand bones, primarily of the extinct prairie dog Cynomys niobrarius churcherii, were recovered from one site, and several hundred more from other locations. Accelerator radiocarbon dates (AMS) on bone collagen show that the prairie dogs lived in the area from at least 33 000 BP to around 22 000 BP. Prairie dog burrow casts crosscut well-developed periglacial structures and stratigraphically underlie all glacial sediments, indicating that harsh periglacial environments preceded their colonization and that the region was later submerged by Laurentide ice. Deformed sediments, 0.5 to 1.5 m thick, were found throughout the upland. The products of deformation overlie, truncate, and (or) incorporate burrow casts, indicating that only limited erosion and glacial deformation occurred during glaciation. Reconstructed ice sheet profiles show a northwest-southeast flow that could only have been achieved by coalescent Laurentide and Cordilleran ice sheets. This demonstrates that a theoretical "ice-free corridor" that some think persisted between the ice sheets during the Late Wisconsin "maximum," did not exist.

Influence of prerelease experience on reintroduced black-footed ferrets ( Mustela nigripes)

Captive breeding is increasingly being used to create supplies of endangered animals for release into natural habitats, but rearing strategies vary and debates arise over which methods are most efficient. We assessed postrelease behaviors and survival of three groups of black-footed ferrets, each with different prerelease experience. Eighteen ferret kits ≤60 days of age were moved with their dams from cages to 80-m 2 outdoor pens with prairie dog burrows. These animals were compared to animals reared in standard cages ( n=72), some of which were given experience killing prairie dogs ( n=32). Ferrets were released onto white-tailed prairie dog ( Cynomys leucurus) colonies in Wyoming, USA, in fall, 1992. Radio-tagged cage-reared ferrets made longer nightly moves and dispersed further from release sites than their pen-reared counterparts. The band return rate was 4-fold higher for pen-reared animals than for cage-reared animals during surveys conducted about 1 month after release. We recommend routine use of quasi-natural outdoor pens for prerelease conditioning of black-footed ferrets.

Dynamics of plague in a Gunnison's prairie dog colony complex from New Mexico.

A plague (Yersinia pestis) epizootic spread through Gunnison's prairie dogs (Cynomys gunnisoni), and possibly other rodent species, in the Moreno Valley in north-central New Mexico between winter 1984-1985 and autumn 1987. We observed the progress of the epizootic and subsequent population recovery at four prairie dog towns within the valley during this period. At two towns (Midlake and Val Verde) the prairie dogs were marked prior to the epizootic. At two additional towns (Vega and South Entrance) prairie dogs were marked following the epizootic. In 1988, a second epizootic occurred at Vega. One hundred thirty-nine serum samples were collected from prairie dogs and other rodents and 1,750 fleas were collected from animals and burrows. Fleas infected with Y. pestis were collected from prairie dogs, deer mice (Peromyscus maniculatus), and thirteen-lined ground squirrels (Spermophilus tridecemlineatus). Prairie dog fleas included Oropsylla hirsuta, O. labis and O. tuberculata, deermouse associated fleas were Aetheca wagneri and Rhadinopsylla sectilis, and Oropsylla bacchi was associated with thirteen-lined ground squirrels. All of the above flea species were collected from prairie dog burrows. All rodent species shared some flea species. Thirteen-lined ground squirrels disappeared shortly before plague was identified in prairie dogs at Midlake. Meadow voles were rare following the epizootic at Vega in 1986, became abundant in 1987, and disappeared at the time of the second prairie dog epizootic in summer 1988. Although we collected serum from Gunnison's prairie dogs, thirteen-lined ground squirrels, deer mice, and meadow voles (Microtus pennsylvanicus), we identified elevated serum titers against Y. pestis only in Gunnison's prairie dogs. Prairie dog mortality at all towns affected by plague was in excess of 99%. Serum antibody titers indicate that more than 40% of the few prairie dogs left to establish colonies following epizootics survived plague infection.

Factors Influencing Burrowing Owl (Speotyto cunicularia) Nest Densities and Numbers in Western Nebraska

-Burrowing owls (Speotyto cunicularia) were studied at 21 prairie dog towns in native prairie and 17 native prairie pastures with badger (Taxidea taxus) burrows in the Nebraska panhandle in the spring and summer from 1989-1991. The number of nesting burrowing owl pairs ranged from 1-20 in prairie dog (Cynomys ludovicianus) towns and from 1-4 in pastures with badger burrows. Burrowing owl densities in small prairie dog towns ( 35 ha) prairie dog towns ranged from 0.9-2.5 owls/ha. Mean nearest-neighbor distance (?SE) in clusters within large (?35 ha) prairie dog towns was 125.0 m + 4.6, whereas the mean distance between owl nests in small towns (<35 ha), where owls did not have the space to cluster, was 105.1 m + 7.4. Mean nearest-neighbor distance for owls nesting in pastures with badger burrows was 240.2 m ? 39.2. No relationship was found between owl numbers and number of active or inactive prairie dog burrows. In 1990 burrowing owl density was inversely related to active burrow density, but no relationship was found in 1991. Burrow availability may be a limiting factor for owls nesting in pastures with badger burrows. As the size (ha) of prairie dog towns increased, burrowing owls occurred in higher numbers but lower densities.

Effects of diet on captive black-footed ferret (Mustela nigripes) food preference

Black-footed ferrets (Mustela nigripes) are both habitat and prey specialists that depend on prairie dogs (Cynomys spp.) for food and utilize prairie dog burrows for refuge. In this study we investigated the effects of captive diet during early development on adult black-footed ferret food preferences. To test the hypothesis that early diet affects the food preferences of adult black-footed ferrets, we exposed 22 kits (divided into three experimental groups) to different quantities of prairie dog in the diet: no prairie dog, prairie dog three times per week, and prairie dog daily during the assumed sensitive period for olfactory imprinting, i.e., between 60–90 postnatal days. At age 5 months, kits were individually tested in a food choice cafeteria trial. Results indicated that higher amounts of prairie dog in the ferrets' early diet led to a higher preference for this food item when ferrets reached adulthood. These results have important implications for black-footed ferret recovery and have been considered in the reintroduction protocol. © 1996 Wiley-Liss, Inc.

Water Relations of Agropyron smithii and Bouteloua gracilis and Community Evapotranspiration Following Long-term Grazing by Prairie Dogs

-The influence of intensive grazing on canopy microclimate, grass leaf water relations and community evapotranspiration was investigated by comparing a grassland heavily grazed by a colony of black-tailed prairie dogs (Cynomys ludovicianus) with an adjacent lightly-grazed, uncolonized area in a northern-mixed prairie in South Dakota. Total aboveground plant biomass was lower on the colony through the growing season. Daytime leaf and air temperatures were higher on the colony. Although daytime air vapor pressure in the canopy was higher on the colony, higher leaf temperatures resulted in higher leaf-to-air vapor-pressure differences on the colony. Along with higher vapor-pressure differences, higher wind speeds within the canopy probably also contributed to higher evaporative demand. In spite of this, the dominant grasses, Agropyron smithii and Bouteloua gracilis, had consistently higher leaf conductances to water vapor and water potentials (4) on the colony, especially later in the day and growing season. Predawn leaf 'p were higher on the colony in July and August, suggesting available soil moisture in the rooting zone was higher there. At the community level, afternoon evapotranspiration rates were lower on the colony in June, but higher on the colony in July and August as soil water became more limiting. While intensive grazing by prairie dogs lead to a warmer canopy microclimate with higher evaporative demand, any detrimental effects on plant water status were apparently offset by greater available soil moisture, especially later in the day and season. Greater soil water availability on the colony was probably the result of smaller transpiring leaf mass (and area), although soil factors such as improved infiltration due to prairie dog burrows can not be ruled out as causative factors.

Control of Oropsylla hirsuta, a plague vector, by treatment of prairie dog burrows with 0.5% permethrin dust.

Permethrin, a pyrethroid insecticide, applied on two plots with a pressurized hand-held duster at mean rates of 2.3 and 4.0 g per burrow, was used to determine control levels for Oropsylla hirsuta fleas, a vector of bubonic plague, in black-tail prairie dog, Cynomys ludovicianus, burrows in northern Colorado during the summer of 1988. Burrows were sampled by "flagging" at day 0 and weeks 1, 3, 6, 9, and 12 to determine the mean number of fleas per burrow and percentage of burrows with at least one flea. The 4.0 g per burrow rate was highly effective (P less than 0.001) in controlling fleas for a period of 3 mo, whereas the 2.3 g per burrow rate was not.

Development of survival skills in captive-raised Siberian polecats (Mustela eversmanni) I: Locating prey

Captive-raised mustelids appear to have a rudimentary capacity to kill prey, but the skills necessary for locating prey may be eroded during captivity. We tested the maturational component of prey-searching behavior with captive-raised Siberian polecats (Mustela eversmanni) by subjecting polecats to a simulated prairie dog colony of 6 burrows within a 200 m2 arena. Ten naive Siberian polecats at ages 2.5, 3.5, and 4.5 months (30 total) were deprived of food for 12 hours. A dead prairie dog was placed in 1 prairie dog burrow and the other 5 were empty. A single Siberian polecat was released onto the colony shortly before sunset and its movements monitored from an observation tower. Older Siberian polecats located prey significantly quicker than younger polecats, but all age groups spent a great deal of time in surface activity not directed toward a burrow. When Siberian polecats were about 10 months old, all burrows in the arena were plugged with dirt including the burrow with the prairie dog. In this winter test, Siberian polecats located the prey but still spent a great deal of time in non-burrow directed surface activity. Economical use of surface time, with a low amount of non-burrow directed behavior, would presumably reduce the risk of predation for hunting polecats.

Efficacy of Zinc Phosphide and Strychnine for Black-Tailed Prairie Dog Control

Three rodenticide treatments, zinc phosphide (prebrited) and strychnine (both with and without prebrit), were evaluated immediately following treatment for efficacy of controlling bircktailed prairie dogs in western South Dakota. Active prairie dog burrows were reduced 95% with zinc phosphide, 83% with strychnine (prebaited), and 45% with strychnine without prebait. Zinc phosphide was the most effective in reducing active burrows of prairie dogs. The black-tailed prairie dog (Cynomys ludovicianus) inhabits prairie regions of the western United States from Canada to Mexico, east of the Rocky Mountains and west of the tall grass prairie (Hal1 198 1). Prairie dog towns often encompass vast areas. Because prairie dog feeding and burrowing activities conflict directly with interests of ranchers and range managers, widespread control programs using rodenticides were begun in the late 1800’s on the Great Plains (Merriam 1902). Prairie dogs are still considered a problem when they compete with cattle for forage plants (Hansen and Gold 1977). Most recent prairie dog control programs on federal, state, and private lands consist of poisoning prairie dogs with zinc phosphide on rolled oats after prebaiting with rolled oats (Schenbeck 1982). Zinc phosphide has been widely used as a rodenticide since 1942-43 when strychnine supplies became limited during World War II (Timm 1983). More recently, zinc phosphide formulation and application rates have been developed for use in prairie dog control (Tietjen 1976). Strychnine has been used for prairie dog control since the late 1800’s (Merriam 1902). These two rodentitides are widely used for prairie dog control throughout the western United States. However, comparative information of these two rodenticides for effective control of black-tailed prairie dogs has not been reported. This investigation was undertaken to compare the efficacy of rodenticides zinc phosphide (pre-baited) and strychnine with and without prebaiting for controlling black-tailed prairie dogs in western South Dakota. Study Area

Territoriality and Interspecific Aggression in Steamer-Ducks

indicates that Burrowing Owls modify prairie dog burrows used as nest sites. Presumably, sandy soil would facilitate enlarging burrow passageways. Coulombe (1971) stated that in California burrow diameters averaged 20 cm, and suggested that owls may modify burrows that have been abandoned by rodents. In addition, sandy soils drain rapidly, which would reduce nest flooding during frequent spring and summer rainstorms.

Field evaluations of dichlorvos as a vapor toxicant for control of prairie dog fleas.

Three field trials of 18.6% dichlorvos-impregnated plastic pellets applied in prairie dog burrows for flea control were conducted in southeast New Mexico. In the 1st test, the application of approximately 28 g of pellets into each burrow opening within a 4.7-ha section of a large prairie dog colony (336.4 g/ha actual dichlorvos) resulted in effective flea control. Flea indices were depressed in less than 16 hr, and remained depressed through 14 days posttreatment. A 2nd test, utilizing a dosage rate of about 14g of pellets per burrow opening in a 3.3-ha plot (215.7 g/ha actual dichlorvos) resulted in a similar initial reduction of fleas within the burrows. In a replication of the 28-g treatment, similarly immediate and effective flea control was demonstrated with an application rate of 268.7 g/ha actual dichlorvos throughout a 6.3-ha plot.

Control of the plague vector Opisocrostis hirsutus, by treatment of prairie dog (Cynomys ludovicianus) burrows with 2 per cent carbaryl dust.

Treatment of prairie dog (Cynomys ludovicianus) burrows with 2% carbaryl (Sevin®)2 dust at a rate of 85–95 g per burrow resulted in 100% elimination of the plague vector, Opisocrostis hirsutus, within 24 hr. Treated burrows remained free of fleas from 8 August to 25 September 1969, while fleas increased in an untreated portion of the same colony. During the winter, all Cynomys in the untreated portion of the study colony died; those in the treated portion survived. Epizootic plague die-off in nearby colonies during the summer of 1969 suggests that die-off in the untreated study plot also was due to plague, although no direct evidence was obtained. This being so, the elimination of fleas by 2% carbaryl protected the treated population from direct exposure to plague.