Search USGS⌕ Search

Geology topics

Dean E. Biggins

Publications and source records attributed to Dean E. Biggins.

At least 73 records · Page 4Linked to original sources
USGS2012

Fine-scale habitat use of reintroduced black-footed ferrets on prairie dog colonies in New Mexico

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.

New Mexico↗
USGS2011

Deltamethrin flea-control preserves genetic variability of black-tailed prairie dogs during a plague outbreak

Genetic variability and structure of nine black-tailed prairie dog (BTPD, Cynomys ludovicianus ) colonies were estimated with 15 unlinked microsatellite markers. A plague epizootic occurred between the first and second years of sampling and our study colonies were nearly extirpated with the exception of three colonies in which prairie dog burrows were previously dusted with an insecticide, deltamethrin, used to control fleas (vectors of the causative agent of plague, Yersinia pestis ). This situation provided context to compare genetic variability and structure among dusted and non-dusted colonies pre-epizootic, and among the three dusted colonies pre- and post-epizootic. We found no statistical difference in population genetic structures between dusted and non-dusted colonies pre-epizootic. On dusted colonies, gene flow and recent migration rates increased from the first (pre-epizootic) year to the second (post-epizootic) year which suggested dusted colonies were acting as refugia for prairie dogs from surrounding colonies impacted by plague. Indeed, in the dusted colonies, estimated densities of adult prairie dogs (including dispersers), but not juveniles (non-dispersers), increased from the first year to the second year. In addition to preserving BTPDs and many species that depend on them, protecting colonies with deltamethrin or a plague vaccine could be an effective method to preserve genetic variability of prairie dogs.

Montana↗
USGS2011

Interface between black-footed ferret research and operational conservation

Questions and problems that emerged during operational conservation of black-footed ferrets ( Mustela nigripes ) have been addressed by a wide variety of studies. Early results from such studies often were communicated orally during meetings of recovery groups and in written form using memoranda, unpublished reports, and theses. Typically, implementation of results preceded their publication in widely distributed journals. Many of these studies eventually were published in journals, and we briefly summarize the contents of 8 volumes and special features of journals that have been dedicated to the biology of ferrets and issues in ferret recovery. This year marks the 30th anniversary of rediscovery of the black-footed ferret, and the 7 papers of the following Special Feature summarize data collected over nearly that span of time.

Journal of Mammalogy↗
USGS2011

Evaluation of a black-footed ferret resource utilization function model

Resource utilization function (RUF) models permit evaluation of potential habitat for endangered species; ideally such models should be evaluated before use in management decision‐making. We evaluated the predictive capabilities of a previously developed black‐footed ferret ( Mustela nigripes ) RUF. Using the population‐level RUF, generated from ferret observations at an adjacent yet distinct colony, we predicted the distribution of ferrets within a black‐tailed prairie dog ( Cynomys ludovicianus ) colony in the Conata Basin, South Dakota, USA. We evaluated model performance, using data collected during post‐breeding spotlight surveys (2007–2008) by assessing model agreement via weighted compositional analysis and count‐metrics. Compositional analysis of home range use and colony‐level availability, and core area use and home range availability, demonstrated ferret selection of the predicted Very high and High occurrence categories in 2007 and 2008. Simple count‐metrics corroborated these findings and suggested selection of the Very high category in 2007 and the Very high and High categories in 2008. Collectively, these results suggested that the RUF was useful in predicting occurrence and intensity of space use of ferrets at our study site, the 2 objectives of the RUF. Application of this validated RUF would increase the resolution of habitat evaluations, permitting prediction of the distribution of ferrets within distinct colonies. Additional model evaluation at other sites, on other black‐tailed prairie dog colonies of varying resource configuration and size, would increase understanding of influences upon model performance and the general utility of the RUF.

South Dakota↗
USGS2011

Environmental enrichment affects adrenocortical stress responses in the endangered black-footed ferret

Potential stressors of wildlife living in captivity, such as artificial living conditions and frequent human contact, may lead to a higher occurrence of disease and reduced reproductive function. One successful method used by wildlife managers to improve general well-being is the provision of environmental enrichment, which is the practice of providing animals under managed care with environmental stimuli. The black-footed ferret ( Mustela nigripes ) is a highly-endangered carnivore species that was rescued from extinction by removal of the last remaining individuals from the wild to begin an ex situ breeding program. Our goal was to examine the effect of environmental enrichment on adrenocortical activity in ferrets by monitoring fecal glucocorticoid metabolites (FGM). Results demonstrated that enrichment lowered FGM in juvenile male ferrets, while increasing it in adult females; enrichment had no effect on FGM in juvenile females and adult males. These results correspond with our findings that juvenile males interacted more with the enrichment items than did adult females. However, we did not detect an impact of FGM on the incidence of disease or on the ability of ferrets to become reproductive during the following breeding season. We conclude that an environmental enrichment program could benefit captive juvenile male ferrets by reducing adrenocortical activity.

General and Comparative Endocrinology↗
USGS2011

Recommended methods for range-wide monitoring of prairie dogs in the United States

One of the greatest challenges for conserving grassland, prairie scrub, and shrub-steppe ecosystems is maintaining prairie dog populations across the landscape. Of the four species of prairie dogs found in the United States, the Utah prairie dog (Cynomys parvidens) is listed under the Endangered Species Act (ESA) as threatened, the Gunnison's prairie dog (C. gunnisoni) is a candidate for listing in a portion of its range, and the black-tailed prairie dog (C. ludovicianus) and white-tailed prairie dog (C. leucurus) have each been petitioned for listing at least once in recent history. Although the U.S. Fish and Wildlife Service (USFWS) determined listing is not warranted for either the black-tailed prairie dog or white-tailed prairie dog, the petitions and associated reviews demonstrated the need for the States to monitor and manage for self-sustaining populations. In response to these findings, a multi-State conservation effort was initiated for the nonlisted species which included the following proposed actions: (1) completing an assessment of each prairie dog species in each State, (2) developing a range-wide monitoring protocol for each species using a statistically valid sampling procedure that would allow comparable analyses across States, and (3) monitoring prairie dog status every 3-5 years depending upon the species. To date, each State has completed an assessment and currently is monitoring prairie dog status; however, for some species, the inconsistency in survey methodology has made it difficult to compare data year-to-year or State-to-State. At the Prairie Dog Conservation Team meeting held in November 2008, there was discussion regarding the use of different methods to survey prairie dogs. A recommendation from this meeting was to convene a panel in a workshop-type forum and have the panel review the different methods being used and provide recommendations for range-wide monitoring protocols for each species of prairie dog. Consequently, the Western Association of Fish and Wildlife Agencies (WAFWA), in coordination with USFWS and U.S. Geological Survey (USGS), hosted a prairie dog species survey methodology workshop January 25-28, 2010 in Fort Collins, Colorado. The workshop provided all WAFWA partners and interested parties the opportunity to present their survey methodology to a review panel made up of experts in the fields of quantitative biology, population biology, species biology, and biostatistics. This report presents the panel's survey methodology recommendations for each of the four species of prairie dogs found in the United States and, for the black-tailed prairie dog, a list of action items to facilitate implementation of the recommended methodology.

Scientific Investigations Report↗
USGS2010

Vector control improves survival of three species of prairie dogs ( Cynomys ) in areas considered enzootic for plague

Plague causes periodic epizootics that decimate populations of prairie dogs (PDs) ( Cynomys ), but the means by which the causative bacterium ( Yersinia pestis ) persists between epizootics are poorly understood. Plague epizootics in PDs might arise as the result of introductions of Y. pestis from sources outside PD colonies. However, it remains possible that plague persists in PDs during interepizootic periods and is transmitted at low rates among highly susceptible individuals within and between their colonies. If this is true, application of vector control to reduce flea numbers might reduce mortality among PDs. To test whether vector control enhances PD survival in the absence of obvious plague epizootics, we reduced the numbers of fleas (vectors for Y. pestis ) 96–98% (1 month posttreatment) on 15 areas involving three species of PDs ( Cynomys leucurus , Cynomys parvidens in Utah, and Cynomys ludovicianus in Montana) during 2000–2004 using deltamethrin dust delivered into burrows as a pulicide. Even during years without epizootic plague, PD survival rates at dusted sites were 31–45% higher for adults and 2–34% higher for juveniles compared to survival rates at nondusted sites. Y. pestis was cultured from 49 of the 851 flea pools tested (6882 total fleas) and antibodies against Y. pestis were identified in serum samples from 40 of 2631 PDs. Although other explanations are possible, including transmission of other potentially fatal pathogens by fleas, ticks, or other ectoparasites, our results suggest that plague might be maintained indefinitely in PD populations in the absence of free epizootics and widespread mortality among these animals. If PDs and their fleas support enzootic cycles of plague transmission, there would be important implications for the conservation of these animals and other species.

Vector-Borne and Zoonotic Diseases↗
USGS2010

Enzootic plague reduces black-footed ferret (Mustela nigripes) survival in Montana

Black-footed ferrets ( Mustela nigripes ) require extensive prairie dog colonies ( Cynomys spp.) to provide habitat and prey. Epizootic plague kills both prairie dogs and ferrets and is a major factor limiting recovery of the highly endangered ferret. In addition to epizootics, we hypothesized that enzootic plague, that is, presence of disease-causing Yersinia pestis without any noticeable prairie dog die off, may also affect ferret survival. We reduced risk of plague on portions of two ferret reintroduction areas by conducting flea control for 3 years. Beginning in 2004, about half of the ferrets residing on dusted and nondusted colonies were vaccinated against plague with an experimental vaccine (F1-V fusion protein). We evaluated 6-month reencounter rates (percentage of animals observed at the end of an interval that were known alive at the beginning of the interval), an index to survival, for ferrets in four treatment groups involving all combinations of vaccination and flea control. For captive-reared ferrets (115 individuals observed across 156 time intervals), reencounter rates were higher for vaccinates (0.44) than for nonvaccinates (0.23, p  = 0.044) on colonies without flea control, but vaccination had no detectable effect on colonies with flea control (vaccinates = 0.41, nonvaccinates = 0.42, p  = 0.754). Flea control resulted in higher reencounter rates for nonvaccinates ( p  = 0.026), but not for vaccinates ( p  = 0.508). The enhancement of survival due to vaccination or flea control supports the hypothesis that enzootic plague reduces ferret survival, even when there was no noticeable decline in prairie dog abundance. The collective effects of vaccination and flea control compel a conclusion that fleas are required for maintenance, and probably transmission, of plague at enzootic levels. Other studies have demonstrated similar effects of flea control on several species of prairie dogs and, when combined with this study, suggest that the effects of enzootic plague are widespread. Finally, we demonstrated that the experimental F1-V fusion protein vaccine provides protection to ferrets in the wild.

Vector-Borne and Zoonotic Diseases↗
USGS2009

A review of plague persistence with special emphasis on fleas

Sylvatic plague is highly prevalent during infrequent epizootics that ravage the landscape of western North America. During these periods, plague dissemination is very efficient. Epizootics end when rodent and flea populations are decimated and vectored transmission declines. A second phase (enzootic plague) ensues when plague is difficult to detect from fleas, hosts or the environment, and presents less of a threat to public health. Recently, researchers have hypothesized that the bacterium (Yersinia pestis) responsible for plague maintains a continuous state of high virulence and thus only changes in transmission efficiency explain the shift between alternating enzootic and epizootic phases. However, if virulent transmission becomes too inefficient, strong selection might favor an alternate survival strategy. Another plausible non-exclusive hypothesis, best supported from Asian field studies, is that Y. pestis persists (locally) at foci by maintaining a more benign relationship within adapted rodents during the long expanses of time between outbreaks. From this vantage, it can revert to the epizootic (transmission efficient) form. Similarly, in the United States (US), enzootic plague persistence has been proposed to develop sequestered within New World rodent carriers. However, the absence of clear support for rodent carriers in North America has encouraged a broader search for alternative explanations. A telluric plague existence has been proposed. However, the availability of flea life stages and their hosts could critically supplement environmental plague sources, or fleas might directly represent a lowlevel plague reservoir. Here, we note a potentially pivotal role for fleas. These epizootic plague vectors should be closely studied with newer more exacting methods to determine their potential to serve as participants in or accomplices to a plague persistence reservoir.

Journal of Vector Borne Diseases↗
USGS2006

A history of searches for black-footed ferrets

Studies of wild populations of black-footed ferrets (Mustela nigripes) in South Dakota in the 1960s, in Wyoming in the 1980s, and of captive-bred ferrets reintroduced to unoccupied habitat in Wyoming, South Dakota, and Montana in the 1990s contributed to our understanding of ferret behavior and improved techniques to find ferret populations. We chronicle the efforts of private, State, and Federal institutions that used these techniques to locate remaining populations of ferrets. During the 1980s, a renewed survey effort and solicitation of new sightings, coupled with a monetary reward program, failed to locate ferrets. We believe that the probability of finding ferrets from noncaptive stock is already small and diminishes with each passing year.

Conference Paper↗
USGS2006

Does predator management enhance survival of reintroduced black-footed ferrets?

Predation on black-footed ferrets (Mustela nigripes) is a potential problem at reintroduction sites, causing up to 95 percent of the documented mortality of ferrets. Strategies to reduce mortality due to predation can focus on preconditioning ferrets prior to reintroduction and/or managing predators of ferrets. Biologists have tried three general strategies to control predators at reintroduction sites: (1) selective removal of individual predators, (2) nonselective removal of coyotes (Canis latrans), and (3) electric fences to exclude coyotes from release sites. We conducted a post hoc review of data from releases during 1994–2003 at 11 sites in South Dakota and Montana to address whether or not predator management has benefited reintroduced black-footed ferrets. Limited evidence indicates that (1) individual great horned owls (Bubo virginianus) can cause significant ferret mortality and that identifying and removing these individuals can be beneficial, (2) lethal control of coyotes may have inverse effects on ferret survival, and (3) electric fencing does not enhance short- or long-term survival of reintroduced ferrets. The data are confounded by a variety of factors, making conclusions tenuous. Well designed studies are needed to properly address the effectiveness of predator management for enhancing ferret survival.

Conference Paper↗
USGS2006

Evaluating habitat for black-footed ferrets: Revision of an existing model

Black-footed ferrets (Mustela nigripes) are highly dependent on prairie dogs (Cynomys spp.) as prey, and prairie dog colonies are the only known habitats that sustain black-footed ferret populations. An existing model used extensively for evaluating black-footed ferret reintroduction habitat defined complexes by interconnecting colonies with 7-km line segments. Although the 7-km complex remains a useful construct, we propose additional, smaller-scale evaluations that consider 1.5-km subcomplexes. The original model estimated the carrying capacity of complexes based on energy requirements of ferrets and density estimates of their prairie dog prey. Recent data have supported earlier contentions of intraspecific competition and intrasexual territorial behavior in ferrets. We suggest a revised model that retains the fixed linear relationship of the existing model when prairie dog densities are <18/ha and uses a curvilinear relationship that reflects increasing effects of ferret territoriality when there are 18–42 prairie dogs per hectare. We discuss possible effects of colony size and shape, interacting with territoriality, as justification for the exclusion of territorial influences if a prairie dog colony supports only a single female ferret. We also present data to support continued use of active prairie dog burrow densities as indices suitable for broad-scale estimates of prairie dog density. Calculation of percent of complexes that are occupied by prairie dog colonies was recommended as part of the original habitat evaluation process. That attribute has been largely ignored, resulting in rating anomalies.

Conference Paper↗
USGS2006

Habitat preferences and intraspecific competition in black-footed ferrets

We used radio-telemetry data (28,560 positional fixes) collected on 153 black-footed ferrets (Mustela nigripes) to (1) reexamine the assumed obligate relationship of these ferrets to prairie dogs (Cynomys spp.), (2) investigate habitat preferences of ferrets at a small scale (1 year (P = 0.048). Also, preference was stronger for wild-born young ferrets than for young captive-born ferrets released to augment the wild population (P = 0.040). This additional evidence for competition among ferrets, and for an advantage of prior residency, raises conservation concerns. The energetics-based model commonly used to predict ferret densities at reintroduction sites does not consider competition, which likely leads to overestimation of the densities of ferrets attainable in high-quality habitat. During sequential releases of ferrets, prior residency may handicap success of newcomers, even though the latter may have higher potential fitness. Although the manner of initial colonization of available habitat by blackfooted ferrets, and their subsequent competition for it, was suggestive of an ideal despotic distribution, we did not assess effects of prey density or burrow density on fitness.

Conference Paper↗
USGS2006

Modeling black-footed ferret energetics: Are southern release sites better?

Several models have been developed to estimate prey requirements and to assess habitat suitability of release sites for the black-footed ferret (Mustela nigripes) (e.g., Stromberg and others, 1983; Powell and others, 1985; Biggins and others, 1993). None of these models, however, addressed possible differences in energetic requirements between sites due to climatic differences within the ferret’s historical range. We used a simplified energetics model to examine the effect of variation in environmental conditions on ferret energetic requirements. The aim of the study was to determine whether the ferret might be more successful in one area than another.

Conference Paper↗
USGS2006

Monitoring black-footed ferrets during reestablishment of free-ranging populations: Discussion of alternative methods and recommended minimum standards

Although the monitoring of black-footed ferret (Mustela nigripes) populations following reintroductions has not been haphazard, several ferret recovery groups since 1994 have recommended development of uniform standards prescribing minimum methods, intensities, and frequencies of monitoring that would provide data on population size, mortality rates, and recruitment. Such standards would promote comparability of data among sites, document expectations for those who will attempt to establish new populations, and allow the U.S. Fish and Wildlife Service and other responsible groups to better assess progress made toward achieving recovery objectives. Our recommendations are based on methods that have been successfully used to monitor natural and reintroduced populations of ferrets and are an attempt to balance needs and costs. We suggest a combination of marking ferrets with passive integrated transponder (PIT) tags and annual spotlight searches coupled with automated transponder readers to individually identify survivors. Unmarked ferrets should be captured and implanted with PIT tags whenever possible. These and other methods are detailed. Circumstances that may dictate other methods or more intensive monitoring (e.g., high rates of loss or low recruitment) also are discussed.

Conference Paper↗
USGS2006

Postrelease movements and survival of adult and young black-footed ferrets

A successful captive breeding program for highly endangered black-footed ferrets (Mustela nigripes) has resulted in surplus animals that have been released at multiple sites since 1991. Because reproductive output of captive ferrets declines after several years, many adult ferrets must be removed from captive breeding facilities annually to keep total production high. Adults are routinely released, with young-of-the-year, on prairie dog (Cynomys spp.) colonies. We evaluated postrelease movements and survival rates for 94 radio-tagged young and adult ferrets. Radio-tagged adult ferrets made longer movements than young ferrets during the night of release and had significantly lower survival rates for the first 14 days. Coyotes (Canis latrans) caused the largest number of ferret losses. A larger data set of 623 ferrets represented adults and young that were individually marked with passive integrated transponders but were not radio tagged. Minimum survival rates, calculated primarily from ferrets detected during spotlight searches and identified with tag readers, again were significantly lower for adults than for young ferrets at 30 days postrelease (10.1 percent and 45.5 percent survival, respectively) and at 150 days postrelease (5.7 percent and 25.9 percent). Assessment of known survival time by using linear modeling demonstrated a significant interaction between age and sex, with greater disparity between adults and kits for females than for males. Postrelease survival of adult ferrets might be increased if animals were given earlier and longer exposure to the quasinatural environments of preconditioning pens.

Conference Paper↗
USGS2006

Radio telemetry for black-footed ferret research and monitoring

By 1973, radio telemetry was regarded as an important potential tool for studying the elusive, nocturnal, and semifossorial black-footed ferret (Mustela nigripes), but fears of using invasive techniques on this highly endangered mammal caused delays. We began radio collaring ferrets in 1981. Use of radio telemetry on ferrets proved to be both challenging and rewarding. We document two decades of development and use that led to the present radio-tagging techniques and methods for radio tracking. The 7-g radio collar commonly used after 1992 was smaller and lighter, relative to mass and size of subjects, than collars used in studies of other Mustela. Other important developments were a Teflon® coating to shed mud, a highly flexible stainless steel cable for whip antennas, and a nondurable wool collar. Although collar-caused neck abrasions have continued to occur sporadically, a retrospective assessment of minimum survival rates for 724 reintroduced ferrets (392 radio tagged), using data from spotlight surveys, failed to detect negative effects of radio-collars. In a South Dakota study, ferrets that were found to have hair loss or neck abrasions when collars were removed did not exhibit movements significantly different from those of radio-tagged ferrets with no evidence of neck problems. Prototype transmitters designed for surgical implantation had insufficient power output for effective use on ferrets. Early attempts at tracking radio-tagged ferrets by following the signal on foot quickly gave way to following movements by triangulation, which does not disturb the subjects. The most effective tracking stations were camper trailers fitted with rotatable, 11-element, dual-beam Yagi antennas on 6-m masts. We used radio telemetry to produce 83,275 lines of data (44,191 indications of status and 39,084 positional fixes via triangulation) for 340 radio-collared ferrets during the reintroduction program. Tracking by hand and from aircraft augmented triangulation, allowing us to locate animals that dispersed long distances and enabling us to determine causes of mortality. Justifying further use of radio telemetry on black-footed ferrets requires careful consideration of costs and benefits.

Conference Paper↗