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such studies often were communicated orally during meetings of recovery groups and in written form using memoranda, unpublished reports, and theses.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.

Radiotelemetry was used during 1983 and 1984 to collect information on short-term areas of activity for black-footed ferrets (Mustela nigripes) near Meeteetse, Wyoming. This population ultimately provided ferrets for the captive-breeding program that bred and released offspring into the wild since 1991. We fitted 5 adult ferrets and 13 juveniles with radiotransmitters and followed their movements during late summer and fall. Adult males had 7-day areas of activity that were >6 times as large as those of adult females. Activity areas of adult males varied little in coverage or location on a weekly basis, but females sequentially shifted their areas. Unlike juvenile females, juvenile males tended to leave their natal colonies.

Ecologically equivalent species serve similar functions in different communities, and an ecological surrogate species can be used as a substitute for an equivalent species in a community. Siberian polecats (Mustela eversmanii) and black-footed ferrets (M. nigripes) have long been considered ecological equivalents. Polecats also have been used as investigational surrogates for black-footed ferrets, yet the similarities and differences between the 2 species are poorly understood. We contrasted activity patterns of radiotagged polecats and ferrets released onto ferret habitat. Ferrets tended to be nocturnal and most active after midnight. Polecats were not highly selective for any period of the day or night. Ferrets and polecats moved most during brightly moonlit nights. The diel activity pattern of ferrets was consistent with avoidance of coyotes (Canis latrans) and diurnal birds of prey. Similarly, polecat activity was consistent with avoidance of red foxes (Vulpes vulpes) in their natural range. Intraguild predation (including interference competition) is inferred as a selective force influencing behaviors of these mustelines. Examination of our data suggests that black-footed ferrets and Siberian polecats might be ecological equivalents but are not perfect surrogates. Nonetheless, polecats as surrogates for black-footed ferrets have provided critical insight needed, especially related to predation, to improve the success of ferret reintroductions.

Black-footed ferrets (Mustela nigripes) likely were extirpated from the wild in 1985–1986, and their repatriation depends on captive breeding and reintroduction. Postrelease survival of animals can be affected by behavioral changes induced by captivity. We released neutered Siberian polecats (M. eversmanii), close relatives of ferrets, in 1989–1990 on black-tailed prairie dog (Cynomys ludovicianus) colonies in Colorado and Wyoming initially to test rearing and reintroduction techniques. Captive-born polecats were reared in cages or cages plus outdoor pens, released from elevated cages or into burrows, and supplementally fed or not fed. We also translocated wild-born polecats from China in 1990 and released captive-born, cage-reared black-footed ferrets in 1991, the 1st such reintroduction of black-footed ferrets. We documented mortality for 55 of 92 radiotagged animals in these studies, mostly due to predation (46 cases). Coyotes (Canis latrans) killed 31 ferrets and polecats. Supplementally fed polecats survived longer than nonprovisioned polecats. With a model based on deaths per distance moved, survival was highest for wild-born polecats, followed by pen-experienced, then cage-reared groups. Indexes of abundance (from spotlight surveys) for several predators were correlated with mortality rates of polecats and ferrets due to those predators. Released black-footed ferrets had lower survival rates than their ancestral population in Wyoming, and lower survival than wild-born and translocated polecats, emphasizing the influence of captivity. Captive-born polecats lost body mass more rapidly postrelease than did captive-born ferrets. Differences in hunting efficiency and prey selection provide further evidence that these polecats and ferrets are not ecological equivalents in the strict sense.

Predation can be a critical factor influencing recovery of endangered species. In most recovery efforts lethal and nonlethal influences of predators are not sufficiently understood to allow prediction of predation risk, despite its importance. We investigated whether landscape features could be used to model predation risk from coyotes (Canis latrans) and great horned owls (Bubo virginianus) on the endangered black-footed ferret (Mustela nigripes). We used location data of reintroduced ferrets from 3 sites in South Dakota to determine whether exposure to landscape features typically associated with predators affected survival of ferrets, and whether ferrets considered predation risk when choosing habitat near perches potentially used by owls or near linear features predicted to be used by coyotes. Exposure to areas near likely owl perches reduced ferret survival, but landscape features potentially associated with coyote movements had no appreciable effect on survival. Ferrets were located within 90 m of perches more than expected in 2 study sites that also had higher ferret mortality due to owl predation. Densities of potential coyote travel routes near ferret locations were no different than expected in all 3 sites. Repatriated ferrets might have selected resources based on factors other than predator avoidance. Considering an easily quantified landscape feature (i.e., owl perches) can enhance success of reintroduction efforts for ferrets. Nonetheless, development of predictive models of predation risk and management strategies to mitigate that risk is not necessarily straightforward for more generalist predators such as coyotes.

Black-footed ferrets (Mustela nigripes) apparently were extirpated from all native habitats by 1987, and their repatriation requires a combination of captive breeding, reintroductions, and translocations among sites. Improvements in survival rates of released ferrets have resulted from experience in quasi-natural environments during their rearing. Reestablishment of a self-sustaining wild population by 1999 provided the 1st opportunity to initiate new populations by translocating wild-born individuals. Using radiotelemetry, we compared behaviors and survival of 18 translocated wild-born ferrets and 18 pen-experienced captive-born ferrets after their release into a prairie dog colony not occupied previously by ferrets. Translocated wild-born ferrets moved significantly less and had significantly higher short-term survival rates than their captive-born counterparts. Using mark–recapture methods, we also assessed potential impacts to the established donor population of removing 37% of its estimated annual production of kits. Annual survival rates for 30 ferret kits remaining at the donor subcomplex were higher than rates for 54 ferret kits at the control subcomplex (unmanipulated) for males ( 82%) and females ( 32%). Minimum survival of translocated kits did not differ significantly from survival of those at the control subcomplex. Direct translocation of young, wild-born ferrets from site to site appears to be an efficient method to establish new populations.

The black-footed ferret (Mustela nigripes) went extinct in the wild when the last 18 known ferrets were captured for a captive-breeding program. Following the success of the captive-breeding program, 146 genetically nonessential ferrets were released at the Conata Basin, South Dakota, from 1996 to 1999. We conducted a genetic analysis of the Conata Basin black-footed ferret population from 2001 to 2003 to determine if genetic variation had been lost since the cessation of reintroductions and if demographic- and genetic-based estimates of effective population size (N_e) accurately predicted observed levels of heterozygosity. We used DNA from wild-born kits (n  =  254) in the Conata Basin population (2001–2003) to calculate current genetic diversity levels. Both allelic diversity (A  =  2, both subpopulations) and mean heterozygosity were low for both subpopulations—0.39 ± 0.12 SE in Agate-Sage Creek and 0.39 ± 0.16 SE in Heck Table—but not significantly different from estimates made in 1999. We found no significant difference between observed and expected heterozygosity levels. Demographic-based estimates of N_e were an order of magnitude higher than genetic-based estimates of N_e, but the 2 estimates provide a range of N_e values for the population. This study shows that the Conata Basin ferret population is able to maintain its genetic diversity over time despite its population history.

We investigated postbreeding resource selection by adult black-footed ferrets (Mustela nigripes) on a 452-ha black-tailed prairie dog (Cynomys ludovicianus) colony in the Conata Basin of South Dakota during 2007–2008. We used resource selection functions (RSFs) to evaluate relationships between numbers of ferret locations and numbers of prairie dog burrow openings (total or active), distances to colony edges, and connectivity of patches of burrow openings. In both years ferrets selected areas near edges of the prairie dog colony where active burrow openings were abundant. In the interior of the colony ferrets selected areas with low abundance of active burrow openings. At times, prairie dog productivity (i.e., pup abundance) might be greatest at colony edges often characterized by grasses; ferrets are likely to select areas where refuge and vulnerable prey are abundant. Ferrets could have used interior areas with few active burrow openings as corridors between edge areas with many active burrow openings. Also, in areas with few active burrow openings ferrets spend more time aboveground during movements and, thus, are likely to be more easily detected. These results complement previous studies demonstrating importance of refuge and prey in fine-scale resource selection by ferrets and provide insight into factors that might influence edge effects on ferret space use. Conservation and restoration of colonies with areas with high densities of burrow openings and prairie dogs, and corridors between such areas, are needed for continued recovery of the black-footed ferret. RSFs could complement coarse-scale habitat evaluations by providing finer-scale assessments of habitat for the black-footed ferret.

The endangered snow leopard (Panthera uncia) is widely but sparsely distributed throughout the mountainous regions of central Asia. Detailed information on the status and abundance of the snow leopard is limited because of the logistical challenges faced when working in the rugged terrain it occupies, along with its secretive nature. Camera-trapping and noninvasive genetic techniques have been used successfully to survey this felid. We compared noninvasive genetic and camera-trapping snow leopard surveys in the Gobi Desert of Mongolia. We collected 180 putative snow leopard scats from 3 sites during an 8-day period along 37.74 km of transects. We then conducted a 65-day photographic survey at 1 of these sites, approximately 2 months after scat collection. In the site where both techniques were used noninvasive genetics detected 5 individuals in only 2 days of fieldwork compared to 7 individuals observed in the 65-day camera-trapping session. Estimates of population size from noninvasive genetics ranged between 16 and 19 snow leopards in the 314.3-km² area surveyed, yielding densities of 4.9–5.9 individuals/100 km². In comparison, the population estimate from the 65-day photographic survey was 4 individuals (adults only) within the 264-km² area, for a density estimate of 1.5 snow leopards/100 km². Higher density estimates from the noninvasive genetic survey were due partly to an inability to determine age and exclude subadults, reduced spatial distribution of sampling points as a consequence of collecting scats along linear transects, and deposition of scats by multiple snow leopards on common sites. Resulting differences could inflate abundance estimated from noninvasive genetic surveys and prevent direct comparison of densities derived from the 2 approaches unless appropriate adjustments are made to the study design.

Studying the ecology and behavior of pack animals often requires that most, or all, of the pack members are sampled. A unique opportunity to sample all gray wolf (Canis lupus) pack members arises during the summer months when reproductive packs localize in rendezvous sites. We collected 155–296 scat and hair samples from each of 5 wolf rendezvous sites in central Idaho to evaluate intrapack relationships and determine the efficacy of noninvasive genetic sampling (NGS) for estimating pack size and family relationships. We detected 65 wolves (5–20 wolves per pack) with NGS, and the pack counts from NGS were the same or higher for adults and the same or slightly lower for pups compared with the counts from observation and telemetry. The wolves in each pack were closely related to one another, and all packs included at least 2 years of offspring from the current breeding pair. Three of the packs had additional breeding adults present. In 1 pack pups were produced by a parent–offspring pair and a pair of their inbred full siblings, indicating multiple cases of inbreeding. This targeted NGS approach shows great promise for studying pack size and wolf social structure without the use of radiotelemetry or direct observations.

We examined patterns of habitat occupancy and intensity of habitat use by Asian small-clawed otters (Aonyx cinerea) by sampling 59 hill stream segments in the Western Ghats between February and April 2008, using spraints (otter feces) as an indicator. We used an occupancy-based approach to determine the influence of habitat covariates on detection and occupancy. We also used generalized linear models to model encounter rate of spraints as a function of the habitat covariates. Although occupancy of streams was high before summer showers, it declined drastically after the rains. Sampling time, therefore, indicated otter movement across the area. Altitude was the next-best predictor of occupancy. Intensity of habitat use was influenced most by altitude followed by stream type, with pools preferred over cascades and riffles. Second- and 3rd-order streams were used more intensively than 1st-order streams. The study identifies high-altitude areas with stream pools as important prospective otter habitats and demonstrates the applicability of occupancy-based surveys to identify determinants of occurrence and habitat use of otters.

We determined ringed seal (Pusa hispida) bacular and testicular growth relationships and made interspecific comparisons to species with better-known mating systems to elaborate on current hypotheses about the mating system of the ringed seal. We measured 161 bacula, 251 pairs of testes, and 55 mandibles collected from ringed seals of known age from Inuit subsistence harvests in Arviat and Sanikiluaq, Nunavut, Canada, from 2003 to 2006. Ringed seal bacular and testicular sizes were positively allometric relative to mandibular size for immature males (<7 years of age) but increased isometrically in mature males (≥7 years of age), similar to relationships between bacular size and body length for known polygynous pinnipeds. Adult isometric growth contrasted with harp seals (Pagophilus groenlandicus), a promiscuous species, in which bacular size likely is sexually selected. Our results, combined with previously reported ecological and behavioral ringed seal characteristics, suggest that ringed seals display a polygynous mating system.

The shallow Patagonian Shelf off Península Valdés limits the dive depth of southern elephant seals (Mirounga leonina) to <100 m, an unusual circumstance for this deep-diving species. Beyond the shelf water depths of >1,000 m enable the seals to forage deeper and use the entire water column. We compared the diving pattern of 10 juveniles instrumented with light–temperature loggers to determine if diving effort, measured as dive durations longer than the estimated aerobic dive limit, differed between on-shelf and off-shelf waters. The productive Patagonian Shelf, an environment where juveniles showed lower diving effort, also was used commonly by older seals, which likely displaced juveniles off-shelf periodically, where they exhibited increased diving effort.

In social ungulates particular individuals or cohorts, such as adult females, can lead or initiate foraging movements. We use muskoxen (Ovibos moschatus) as a model system to test hypotheses regarding the sex and age class of leaders and the potential costs of leadership in 3 different behavioral contexts: activity initiation, foraging-bout movements, and spontaneous group movements. We conducted research on approximately 160 muskoxen at Cape Krusenstern National Monument adjacent to the coast of the Chuckchi Sea in northwestern Alaska. We observed free-ranging, mixed-sex groups of muskoxen from the ground during 5 June–22 September 2002. Adult females emerged as leaders in all 3 contexts, and other group members were more likely to follow adult females than adult males during initiations of activity. Half of successful initiations by adult males included aggressive behavior toward females. Males took a more active role during rut (the mating season) by provoking females to initiate group activity and by actively manipulating spontaneous movements led by females through herding and blocking activities. Leaders incurred no obvious costs in terms of lost foraging time. Costs and benefits of leadership can be subtle and difficult to measure in the field and can include foraging and reproductive trade-offs and increased risk of predation.

Tayassuids exhibit little sexual dimorphism. Sex-related craniomandibular variation was tested in 2 tayassuid species with regard to morphology and function. We analyzed skull features from 61 adult and 37 subadult white-lipped peccaries (Tayassu pecari) and 49 adult collared peccaries (Pecari tajacu) of both sexes. Seventeen skull measurements were used for the morphological characterization, and from these, indexes were obtained for the functional analysis of bite performance (temporal and masseter muscular systems) and head elevation (semispinalis capitis/complexus muscular system). Skull sexual dimorphism of the 2 species and 2 age groups were evaluated independently through discriminant function analysis (DFA), principal component analysis (PCA), and univariate methods. The DFA characterized a slight secondary sexual dimorphism in adult T. pecari and P. tajacu skulls and provided sex classification functions. However, no sexual variation was detected in skull function of adults in either species. Nevertheless, subadult males and females of T. pecari displayed marked morphological and functional skull variation. Subadult females displayed greater skull robustness, and their force indexes indicate an enhancement on bite strength and in head elevation. This could suggest ecomorphological dissimilarities between subadult male and female T. pecari. The sexual precocity of the females reported in the literature could be the main determinant of the marked morphofunctional variation among the T. pecari subadults. These sexual differences in skull morphology seem to become reduced as males mature.

Numerous studies have been made of rodent population and community dynamics, especially in arid ecosystems. Most have centered on understanding how total and species-specific densities of rodents change over time. The standing biomass each species contributes also is important to the energy available to the mesocarnivore community. Although density and standing biomass are related, how they might differ and if those differences are of importance to community structure and function have not received much attention. We analyzed 12 years of rodent density and body mass data from the Chihuahuan Desert in northern Mexico. Data were collected yearly in spring and fall from radial livetrapping webs. Total density and biomass changed significantly in a parallel manner from year to year, and both were related to precipitation and percent cover of grass and forbs. Based on density and biomass, the rodent community was dominated by 2 or 3 principal species. However, on a species-specific level, the numerically dominant species was a small-bodied granivore (Chaetodipus nelsoni), and a large-bodied folivore (Neotoma albigula) dominated in biomass. As total density increased, the proportion contributed by dominant species decreased. As total biomass increased, the proportion in the 2 dominant species increased and accounted for approximately 80% of total biomass. Over the 12 years of the study, species distributions based on density showed no directional change. In contrast, biomass of the rodent community gradually concentrated in a single, large-bodied folivore, N. albigula. Although total density and biomass responded similarly to precipitation and plant productivity, considerable differences between these 2 characteristics existed in their species-specific contributions to and changes within the community. The significance of these differences relative to foraging strategies and variable feeding opportunities within the community is discussed.

Mound-building mice (Mus spicilegus) construct large mounds of soil and plant material in autumn, where juvenile animals overwinter in groups without reproducing. The mounds have several functions, including food storage, thermoregulation, and protection from predators. We examined whether these mounds have food storage or thermoregulatory function. Mice used mainly seeds and ears of certain plants (Echinochloa sp., Chenopodium spp., and Setaria spp., depending on availability) as building materials, but microhistological analysis of mice feces revealed that the cached plants are not represented in their actual diet. By comparing the features of soil under the mound to neighboring random points we found that the mounds have water-insulating and thermoregulatory properties. We also found a positive correlation between the size of the mound, its vegetal content, and its effectiveness to lessen the impact of the harsh conditions of the outside environment. Mound size was dependent on the number of inhabitants, indicating that larger mounds are constructed by and shelter bigger groups. The existence of communal mound building thus can contribute greatly to successful overwintering and the relatively low fluctuation in population size in this species.

In polygynous and polygynandrous mating systems males possess a variety of behavioral tactics that increase their access to reproductive females. In addition to overt combat or defending resources that attract mates, males use premating tactics that provide them with subsequent opportunities to copulate with receptive females. For Columbian ground squirrels, Urocitellus columbianus, we report that co-occupation of a burrow system by a reproductive male and a female on the night before the female exhibits diurnal estrus is an example of such a tactic. Our hypothesis was that nocturnal underground association results in successful consortships and therefore constitutes a mating tactic that is complementary to other mating behaviors exhibited during a female's estrus. Under this hypothesis appropriate predictions are that: males co-occupying a burrow system with a female at night should mate first with that female; males co-occupying a burrow system with a female overnight should sire more of her offspring than her subsequent mates; and the reproductive success of males co-occupying a burrow system with females should be higher than the reproductive success of mates that do not. To test our predictions we used a combination of field observations on nocturnal underground consortships (NUCs) and microsatellite DNA analyses of paternity. Males copulated with females during NUCs, as evidenced by inseminations. These males sired more offspring than males that did not participate in NUCs. Males ≥3 years old participated in more NUCs than sexually mature 2-year-old males. Our results supported the hypothesis that entrance into NUCs with a female before she exhibits estrus was a premating tactic that increased male reproductive success when exhibited in concert with other mating tactics such as territorial defense.

Rodents are important components of most modern ecosystems. Understanding their roles in paleocommunities requires robust methods for inferring diet and other autecological characteristics. This pilot study tests whether a relationship between incisor morphology and diet exists among extant rodents that might be used to infer diets of extinct species. We focused on 11 genera of caviomorph rodents classified in 3 dietary categories: fruit–leaf, fruit–seed, and grass–leaf. For each genus 6 variables describing morphology of the upper incisor were measured on 5 specimens. Data were analyzed using a series of stepwise discriminant analyses. Discriminant analyses correctly predicted diets of nearly all training cases (∼95%) using 4 incisor characteristics. Five additional species (1 caviomorph and 4 noncaviomorph), treated as unknowns, also were classified correctly. Jackknife analyses correctly predicted diets of approximately two-thirds of training cases. Our study indicates that incisor morphology is related to diet in extant caviomorph rodents. Incisor data therefore might be useful for inferring diets of extinct species.

The status of early-successional habitats and wildlife species associated with them recently has become a concern in the eastern United States. Although federal farm programs have the potential to create early-successional habitats for wildlife, relatively few studies have assessed wildlife response to these land use changes. During 2006–2007 we studied habitat factors associated with occupancy and detection of 2 species of lagomorphs, swamp rabbit (Sylvilagus aquaticus) and eastern cottontail (Sylvilagus floridanus), in agricultural lands recently afforested via federal farm programs in southern Illinois. Lagomorphs were live captured, and habitat variables were measured at 27 bottomland sites. Detection probabilities of eastern cottontails and swamp rabbits were 0.44 (SE  =  0.05) and 0.12 (SE  =  0.03), respectively. Canopy closure (i (i) > 0.94) had the most influence on detection probability for both eastern cottontails and swamp rabbits. Detection probability decreased with increasing canopy closure for eastern cottontails but increased with increasing canopy closure for swamp rabbits. Eastern cottontails and swamp rabbits were estimated to occupy 80% and 71% of sites, respectively. Little support was found for habitat variables influencing site occupancy by eastern cottontails. Distance to a semipermanently flooded or intermittently exposed wetland had the most influence (w (i)  =  0.54) on the probability of site occupancy by swamp rabbits. Our study provides novel information regarding use of early-successional habitats by eastern cottontails and swamp rabbits and unique insight into how habitat structure and landscape configuration affect these 2 lagomorphs.

Based on a series of specimens collected in Cambodia and Vietnam, this paper describes 3 new species of tube-nosed bats belonging to the Murina “suilla-group” (Vespertilionidae: Murininae). We provide detailed accounts of their external and craniodental morphology, including a suite of standard measurements, and compare the new taxa with all other members of the group currently recognized in Southeast Asia. The 1st new species was previously included in M. tubinaris (Scully, 1881) but is considered distinct due to differences in external and craniodental features. This new species is widespread in continental Southeast Asia and relatively well represented in museum collections, whereas the other new species are known only from a few specimens collected at scattered localities. The new taxa are known only from forested areas, which highlights the incompleteness of existing knowledge and strong potential for further discoveries in the region.