Abstract Weasels can be important components of grassland and meadow communities where they influence the dynamics of small mammal populations which, in turn, can be keystone species in these communities. We evaluate a method for detecting and identifying two species of North American mustelines (i.e., Mustela frenata and M. erminea) in mountain meadow systems. It is based on previous knowledge that weasels often co-opt the winter nests of their vole (or lemming) prey and frequently deposit scats there. We exploit this aspect of the predator-prey relationship and describe how, when paired with genetic identification of species from scat, searching after spring melt for weasel scats in winter-constructed vole nests may be an alternative survey method for detecting weasels in meadows. Our work was conducted at the Sagehen Experimental Forest in the Sierra Nevada Mountains. We discovered and examined 90 winter vole nests over four spring seasons, resulting in an average (SD) of 3.31 (1.81) nests found per survey hour per year. From these nests we collected an average of 0.57 (0.37) putative weasel scats per survey hour. Of the seven scats that were verified to be from a weasel, five were from M. frenata and two from M. erminea. This was a proof of concept effort, to which we conclude that searches of vole nests for scat that can be genetically verified as weasel should have a place in the biologist's toolkit. The method is likely to be the most efficient for obtaining a genetic sample for weasels in mountain meadow systems.

The complex topography, climate, and geological history of Western North America have shaped contemporary patterns of biodiversity and species distributions in the region. Pacific martens (Martes caurina) are distributed along the northern Pacific Coast of North America with disjunct populations found throughout the Northwestern Forested Mountains and Marine West Coast Forest ecoregions of the West Coast. Martes in this region have been classified into subspecies; however, the subspecific designation has been extensively debated. In this study, we use genomic data to delineate conservation units of Pacific marten in the Sierra-Cascade-Coastal montane belt in the western United States. We analyzed the mitochondrial genome for 94 individuals to evaluate the spatial distribution and divergence times of major lineages. We further genotyped 401 individuals at 13 microsatellite loci to investigate major patterns of population structure. Both nuclear and mitochondrial DNA suggest substantial genetic substructure concordant with historical subspecies designations. Our results revealed that the region contains 2 distinct mitochondrial lineages: a Cascades/Sierra lineage that diverged from the Cascades/coastal lineage 2.23 (1.48-3.14 mya), consistent with orogeny of the Cascade Mountain chain. Interestingly, Pacific Martes share phylogeographic patterns similar with other sympatric taxa, suggesting that the complex geological history has shaped the biota of this region. The information is critical for conservation and management efforts, and further investigation of adaptive diversity is warranted following appropriate revision of conservation management designations.

Abstract Food resources can be a limiting factor and natural and anthropogenic influences that alter the abundance of food resources can affect population performance and persistence. Reproduction in mammals is energetically costly; therefore, understanding how food resources influence reproduction is essential, especially for species of conservation concern. The objectives of this study were to characterize Pacific marten (Martes caurina) diets during the denning period and determine whether diets differed by sex or by phase of the denning period. We used 943 scats to reconstruct sex‐specific diets of martens in the Sierra Nevada mountains during the denning period to evaluate sex‐specific hypotheses of predation patterns. During the lactation phase, females preyed primarily on large‐sized prey (62.5% metabolizeable energy) 5.7‐times more than males. This likely optimized both energy gain and minimized time spent away from dependent young. During the weaning phase, females preyed primarily on medium‐ (90–200 g) and large‐sized prey (87.7% metabolizeable energy). During the predispersal phase, females exhibited a 4.7‐fold increase in use of small‐sized (<50 g) prey during the time kits are learning to hunt. Male overall diet and predation patterns appear to fit an optimal foraging strategy that is influenced primarily by prey profitability and abundance, with males preying primarily on medium‐sized prey, closest to meeting their lower energetic needs. In contrast, females appear to fit the predictions for a central place forager that is also influenced by prey profitability, but also the increased energetic and maternal demands of denning, leading them to use larger prey than males over the phases of the denning period when kits are growing. We hypothesize that switching to smaller prey is related to females assisting their kits in developing hunting skills and experience that may increase their chances of survival once they disperse.

Models that predict the distributions and habitat suitability for species of conservation concern can be useful for guiding survey, monitoring, and conservation planning efforts. The Humboldt marten (Martes caurina humboldtensis) has significantly declined throughout its historical range in coastal California and Oregon and this taxon is known from a few remnant populations. We developed a landscape habitat suitability model to identify areas of suitable habitat not yet surveyed, to provide a template for designing monitoring programs and research studies, and to inform the development of a conservation strategy. We used the results of 1,159 occupancy surveys to develop a predictive habitat model using Generalized Additive Modeling to relate Humboldt marten detections to combinations of environmental and habitat attributes hypothesized to influence marten distribution. We measured 30 candidate variables at three spatial scales, using 0.5, 1.0, and 3.0 km, and although several models were competitive, each contained the same three core variables: old growth structural index measured at the 1-km scale, serpentine habitat measured at the 3-km scale, and annual precipitation measured at the 3-km scale. The final model had an overall correct classification rate of 91% for marten detections, 82% for non-detections and a true skill statistic of 0.73. Model predictions were stable when cross-validated, with the correct classification of marten detections (89%) varying little. The largest complexes of predicted suitable habitat occurred in the areas with the three extant marten populations (north coastal California, south coastal Oregon, and central coastal Oregon), however connectivity of suitable habitat to areas outside these three areas appears limited.

The fisher is a mammalian carnivore that chooses resting locations each day. Refugia are essential. thus most of the fisher's resting locations are cavities in large live or dead trees. Tree growth and decomposition influence the creation of cavity-bearing structures, which may take centuries, but they can be lost to fire or harvest in an instant. Thus, the conservation of the fisher relies on an equilibrium between the loss of structures via disturbance and their creation. In the mid-1990s we studied fisher resting habitat by following radio-marked individuals to their resting locations. In 2016, roughly 20 years later, we assessed the risks that the resting structures were exposed to by overlaying the perimeters of fires and tree harvest units on the location of 192 resting structures. We also assess the effect of disturbance by examining 36 of them in the field. The mean distance from a resting structure to the nearest harvest unit was 651 m, with 16.8% estimated to be within a harvest unit. The mean distance of the resting structures to the nearest fire was 635 m with 51.0% estimated to be within a fire. Of 36 resting structures that were reevaluated or relocated in the field. 16 (44.4%) were of questionable use in 2016. Based on GIS analyses of disturbance coupled with field data on relocated structures, approximately 15-25% were potentially usable after 20 years. Managers planning actions should consider this a background level of loss of resting structures over 20 years-a background against which additional vegetation management can be considered.

ABSTRACTAlpine ski recreation is one of the most popular outdoor winter sports globally but often involves habitat modification and dense human activity, both of which can harm wildlife. We investigated the effects of ski area development and winter recreation activities on movement, occupancy, and density of Pacific martens (Martes caurina) in the Lake Tahoe region of California and Nevada, USA by comparing 3 ski and 3 control study areas. We systematically surveyed martens using live traps and hair snares during spring–summer and winter seasons from 2009 through 2011 to identify how martens responded to the year‐round effects of habitat fragmentation from ski area development and the seasonal effects of winter recreation activities. Martens selectively moved between remnant forest patches with the shortest crossing distances across open, non‐forested ski runs in both seasons, with the effect more pronounced in females. Overall, habitat connectivity was reduced by 41% in ski areas compared to habitat not fragmented by ski runs. During spring–summer, occupancy rates were not different between habitat within or outside of ski operations areas. During winter, however, occupancy was significantly lower inside (52%) ski area boundaries than outside (88%) them. Reduced detection probability in ski areas indicated martens also reduced the frequency of use of operations areas in winter. Using spatially explicit capture‐recapture models, we found that marten density did not differ between ski areas and controls during spring, but during winter female density declined at ski areas by 63% compared to spring–summer and was <50% of female density compared to controls. This suggests that females seasonally avoid habitat in ski areas by shifting their habitat use to areas outside ski operations boundaries during winter. Although male marten density did not differ, the lack of resident males >3 years old coupled with higher annual turnover rates suggests male densities at ski areas may be reliant on annual male immigration. In winter, martens avoided using habitat in ski operations areas when recreation activity was greatest. Winter ski recreation may not be incompatible with marten use of habitat in ski areas, but habitat fragmentation from ski areas affects marten movement and recreation activities affect seasonal habitat occupancy and female density. Maintaining functional habitat connectivity, via networks of short ski run crossings that link habitat in and out of ski areas, will be important for maintaining or improving marten use of remnant habitat in developed ski areas. © 2017 The Wildlife Society

Predators may limit populations of small carnivores indirectly through exploitative competition for resources, and directly through interference competition, including predation. We evaluated direct effects of predation by large predators on small, specialist carnivores by estimating annual survival and cause-specific mortality. We used known fate models to estimate annual survival of 23 radio-collared short-tailed weasels (Mustela erminea) in western Oregon in 2012-2013. Further, we reviewed published and unpublished studies of radio-tracked weasels (Mustela spp.) in North America, to identify main predators of weasels and survival. If the study did not report survival but did report number of days tracked and cause-specific mortalities, we extrapolated an annual survival index, based on daily survival rates (Mayfield index), to facilitate comparisons between studies. Estimated mean +/- SD annual survival of short-tailed weasels in our study was 0.26 +/- 0.08, and did not vary by season or sex of the weasel. Most (80%) predation mortalities, however, occurred in winter, and were attributed to predatory birds, suspected to be barred owls (Strix varia). For seven North American studies, including ours, we estimated the average annual survival index for M. erminea and Mustela frenata to be 0.37 +/- 0.28. Across studies, most mortality was attributed to predation. Predators killed weasels >2x more frequently in winter when most mortality (86%) was attributed to predatory birds. Mammalian predators, in contrast, killed weasels most frequently in summer (75%). Our results support the hypothesis that predation may play an important role limiting weasel populations in North America.

The conservation and management of species-at-risk requires periodically collecting information about their distributions and abundances. A comprehensive monitoring plan should, in addition to monitoring the population itself, also assess the status of habitat elements that are key factors in species survival. Places where animals seek safe and secure places to rest are such key habitat elements. We used previously published models to predict resting habitat for fishers (Pekania pennanti) throughout much of their range in California. Unique to this work is that the two models (northwestern California and southern Sierra Nevada) were developed using, as predictors, variables directly from a national plot-based forest inventory program called Forest Inventory and Analysis (FIA). Using these models, relative resting habitat suitability can be estimated at each geographically relevant plot in the FIA system every time the plot is resampled. We applied these predictive models to data collected at 3 time periods over an approximately 20 year period to evaluate the trend in predicted fisher resting habitat. None of the 8 national forests, 4 in the northwestern California region and 4 in the southern Sierra Nevada region nor either of these 2 regions as a whole exhibited trends in predicted resting habitat suitability that were significantly increasing or decreasing. Predicted resting habitat suitability tended to be lower on private land than public land, in both regions. As expected, plots that were disturbed by fire exhibited a decrease in resting habitat suitability but, surprisingly, the few plots within harvest unit boundaries had indistinguishable values before and approximately 7 years after the harvest. Using FIA data for future assessments of habitat value will avoid the significant cost incurred when the data need to be collected repeatedly using different data and a field protocol that may vary. We anticipate that the FIA program will continue to be the preeminent plot-based vegetation survey in the United States, and the data to run the resting habitat models will be available every 10 years. Moreover, access to routinely updated plot-based data provides the only way we can envision sampling something as fine-scaled as resting habitat over thousands of square miles of potentially suitable habitat. We hope our example encourages others to parlay the FIA data into a predictive model of fine-scale habitat features that is relevant to other species. Demonstrating the utility of our models should also encourage managers to use the predictions to evaluate the status of fisher habitat in California.

Solitary carnivores in the family Mustelidae are thought to exhibit pronounced intrasexual territoriality, defending space against competitors but tolerating members of the opposite sex. Although mustelids move long distances daily, how such movements reflect intrasexual territoriality is relatively unknown. We hypothesized that martens make regular movements around the boundaries of their territories and that territories typically would be stable across seasons and years. Consequently, we predicted that high-resolution movement data would reveal territorial boundaries within days to weeks. We collected movement data (from GPS collars) and long-term location data (from VHF collars) for 25 adult Pacific martens (Martes caurina) in 2 study areas (coastal and montane). We used GPS movement data to estimate utilization distributions and evaluate individual overlap and stability of territories between seasons, and compared those with annual home ranges from VHF locations. We also used incremental analysis to calculate how many days of movement data were required to fully describe a marten's territory. Marten territories estimated from GPS movement data were indistinguishable from annual home ranges (spatial overlap, (X) over bar +/- SD, 0.99 +/- 0.13, n = 9) and remained relatively stable year-round with some expansion during winter. Territories of same-sex neighbors overlapped <2%. Our models suggested that an individual marten's movements encompassed 95% of its territory within 2.25-14 days (X = 4.6 days); that time did not differ between study areas, sexes, or seasons. Location data with high spatial and temporal resolution could enable more precise estimates of territoriality in this and potentially other carnivore species, and illuminate hitherto unobservable behavioral differences across time and space.

There is considerable interest in factors controlling “warm-edge” limits – the lower elevation and latitudinal edges of a species' range. Understanding whether conservation measures can mitigate anticipated change in climate requires consideration of future climate as well as species interactions. We explored niche relations of martens and fishers at their southern range margins to understand their spatial and temporal dynamics, and how they may be affected by climate change. We used large-scale non-invasive surveys and home range data from radio-marked individuals to explore the spatial dynamics of each species. Marten and fisher were allopatric in the northern/wetter regions but sympatric at intermediate latitudes with lower precipitation. In the driest/southernmost region only fishers occurred. Martens were not detected when annual precipitation was <900mm and rare where minimum temperatures exceeded 4°C. Fishers were absent where spring snow was >650mm. Classification trees, accounting for multivariate interactions, supported these results. Where sympatric, ~70% of a marten's home range overlapped with at least one fisher but martens tended to avoid this area. In sympatry, marten expanded their niche into areas with reduced snowpack, warmer temperatures and uncharacteristic lower elevation habitats. Future climate scenarios predict conditions that favor fishers, but our data suggest martens may be capable of shifting their niche somewhat to warmer and less snowy habitats. The conservation of interacting species at their warm range limits will require land managers be aware of interspecific tolerance, how each may respond uniquely to future climates, and how potential climate refugia can be integrated with existing habitat.

Carnivorous mammals < 25 kg typically prey on species < 50% of their body mass but can choose prey whose energy value varies from small proportions of their daily needs to exceeding them. We hypothesized that for carnivores < 25 kg specializing in vertebrate prey, prey sizes closest to meeting daily energy needs would be most frequently depredated. We tested this hypothesis by reconstructing the diet of Humboldt martens using 528 scats and calculating the proportion of metabolizable energy (PME) that each prey taxon contributed to the diet. Overall, mammals dominated the diet (PME = 72%), followed by birds (PME = 22%), with berries, insects, and reptiles contributing < 10% PME. Sciurids comprised the largest proportion of all prey, representing 42% of overall PME, ranging from 29% (spring) to 51% (summer). While > 37 prey taxa were identified in the annual diet, only 11 contributed > 5% PME in any single season and the 4 dominant prey taxa in any single season represented 59-64% of that season's PME. Medium-sized prey (85-225 g) composed 55-66% PME from summer through winter and 2.6 to 8.4 times PME compared to small (< 40 g) and large (> 250 g) prey during these 3 seasons, respectively. When PME for the most frequently consumed individual medium-sized prey (e. g., chipmunks) declined seasonally, martens switched to alternative medium-sized prey (2.8-and 2.5-fold increases in medium-sized birds and flying squirrels, respectively), increased use of large prey (> 8-fold increase), but changed use of small prey least. The annual importance of medium-sized prey, and seasonal shifts to similar-sized or larger prey during winter-spring seasons, both support our hypothesis that the most frequently depredated prey in the diet of Humboldt martens have body sizes closest to meeting daily energy needs.

This book is a synthesis of the invited, oral presentations from the Fifth International Martes Symposium held in September 2009. It reflects a very broad range of the current knowledge, often acquired with techniques not available prior to the first book of this nature in 1994. There are five sections to this book, but such a broad overlap between the sections exists that I don’t think they were the best choices; this does not detract from the individual papers at all, but the organization is just a bit odd. These are scientifically written papers, and as such, are directed at peers and serious naturalists. There are a few technical points which bothered me. In the vast majority of scientific writings, the whole num bers one through ten are spelled out, not written as numbers. For long-time readers of science, seeing “5” instead of “five” gives rise to a reading hiccup. It’s also really quite irritating to find a graph axis labelled 0.6, 0.8, 1, 1.2, etc. Authors creating the graphs simply ac cepted sloppy defaults, where they should have insisted on consistent decimal places (e.g. 1.0, not 1) throughout. However, the papers are otherwise quite well written and make the arguments effectively. The first paper, Synthesis of Martes Evolutionary History sets the stage for the animals discussed in this tome. Although the relationships within the genus are well described, a cladogram and brief discussion of the context of the genus among other mustelids would have been appropriate. The reader is exposed here to the possibility that the Wolverine and the Tayra may, with more analysis, be included in Martes, but where are the ot ters, badgers and weasels relative to the martens and their kin? There are two papers centring on parasites; curiously, the one entitled Complex Host-Parasite systems in Martes: Implications for Conservation Biology... does not appear in the section on conservation. None-theless, both papers are well-written and quite interesting (no, this reviewer is not a parasitologist!). The second paper by Gabriel, Wengart and Brown includes a massive table of presumably all the known parasites associated with the genus...a total of almost 250 hostparasite relationships. This table alone would be gold to someone starting out in Martes parasitology. The chapters on habitat use bring to light the unexpected result that these animals are not, as presumed, dependent on old growth forests, neither in Europe nor North America. Given the lack of old growth, this is good news for reintroduction programs. However, the general consensus is that when available, complex forest structure, often found in old growth is preferred. The section on research techniques includes chapters covering the gamut from scat-detecting dogs through radiotelemetry and modelling. In most cases, historical techniques (i.e. prior to 1994) are compared with current ones. Advantages and disadvantages of each technique are often discussed, allowing the reader to critically assess them. The final section contains five chapters dealing with the conservation of Martes populations. The opening chapter, although well written, contains disappointing maps...pixellated and, in the case of the North American maps, uses projections which emphasize the United States, a country largely devoid of these animals, and a compressed Canada, where most of the detail is really necessary. Two graphs within this chapter have seven curves each, giving rise to an unnecessary amount of clutter. This could have been done better. There are two strengths associated with reviews or amalgams of papers like this one (which include re views). The first is that the reader gets the opinions of a diversity of authors, in this case, 62 of them. The second is the wealth of literature cited...a boon to anyone doing this type of research, whether a novice or career Martesologist. This volume cites over 1600 works... could a single paper have been missed?

Weasels Mustela spp. are specialized, small predators which demonstrate pronounced differences in size and social status according to sex and age, and these differences may manifest in spatial patterns including home range size and habitat selection. In forested North America, favored prey (voles; Microtus spp. and Myodes spp.) of short‐tailed weasels Mustela erminea often reach high abundances in early stage forest, but availability of that cover type is limited where intensive plantation forestry occurs. We estimated home range size, including home range core area and arrangement, habitat selection, wet season rest site reuse and movements for 25 (18 M: 7 F) short‐tailed weasels Mustela erminea that we radio‐collared in managed plantation forests in western Oregon, USA in 2012–2013. Average fixed kernel 90% home range size was 51.3 hectares for males (95% confidence interval = 30.8–71.7 ha) and 8.6 hectares for females (95% confidence interval = 6.41–10.79 ha). Juvenile males had larger core areas than adult males, and all females had similar core areas. Core areas for all individuals were negatively correlated with % early stage forest cover. Females strongly selected early stage forest cover at both study area and home range scales, and males were less selective of particular cover types. Home ranges of observed males did not overlap, but partly overlapped the home ranges of females. Short‐tailed weasels reused the same rest site in 43% ± 4 (mean ± SE) of cases observed during the wet season (n = 10 individuals, 292 rest sites). We conclude that space use by short‐tailed weasels in western Oregon is influenced by sex, age, and cover type, especially availability of early stage forest, in managed conifer forests.

Little is known about the ecology and life history of the federally endangered Point Arena mountain beaver (Aplodontia rufa nigra). The distribution of this primitive burrowing rodent is disjunct from the balance of the species' range and occurs in a unique maritime environment of coastal grasslands and forests. Fundamental to protecting this taxon is knowledge of its breeding season and other reproductive characteristics. This information is necessary so that ground-disturbing activities near burrow systems can be scheduled to avoid the breeding season. We examined the reproductive status of 38 individuals, captured 150 times, from June 2004-July 2005 (excluding 01 February-01 May when we were prohibited from trapping). We used changes in vaginal cytology to monitor estrus and we evaluated male breeding readiness by determining whether testes were scrotal. The earliest onset of estrus occurred on 02 December and it was detected until the trapping prohibition period began on 01 February. The first males had scrotal testes somewhat earlier, in late November, and most males were still in this condition when trapping prohibition began. These data suggest an earlier onset of the breeding season than described for other subspecies. All females and a majority of males (70%) examined in December and January had evidence of reproductive condition. No evidence of pregnancy was observed during the study period, but based on allometric equations developed elsewhere, and applied to the weights of juveniles we captured, parturition was estimated to occur in early-to mid-April.

ABSTRACT Simplifying stand structure to reduce fuel density is a high priority for forest managers; however, affects to Pacific marten ( Martes caurina ) movement and connectivity are unknown. We evaluated whether thinning forests to reduce fuels influenced movements of Pacific marten. We collected movement paths from 22 martens using global positioning system telemetry to evaluate habitat selection and describe movement patterns. We quantified motion variance, speed, and path sinuosity in 3 stand types that differed in structural complexity (i.e., complex [dense], simple [thinned], and open). We hypothesized marten movement would differ between stand types and predicted that 1) martens would select stand types with increased structural complexity (complex > simple > open); 2) movements would increase in complexity (sinuosity, motion variance) and decrease in speed when martens traveled through stands with increased structural complexity; 3) speeds would increase during summer, indicating increased movement during the breeding season; and 4) males would move more rapidly because of their larger home ranges. Martens traveled 0.5–27.2 km/day and an average (SD) of 1.4 (0.4) km/hour. Martens selected home ranges with fewer openings compared to the study area overall. Within home ranges, martens strongly selected complex stands over simple stands and openings. Speed and movement complexity were most consistent over time and movements were more sinuous and slower in complex stand types compared with openings and simple stands. Movement was erratic and more linear in openings than in both complex and simple stands. In simple stands, movement patterns were intermediate between complex stands and openings. Females generally moved more slowly, sinuously, and less variably compared to males. Martens moved more quickly, less sinuously, and more variably during winter compared to summer. However, martens avoided stands with simplified structure, and the altered patterns of movement we observed in those stands suggested that such treatments may negatively affect the ability of martens to forage without increased risk of predation. Fuel treatments that simplify stand structure negatively affected marten movements and habitat connectivity. Given these risks, and because treating fuels is less justified in high elevation forests, the risks can be minimized by applying treatments below the elevations where martens typically occur. © 2016 The Wildlife Society.

Resting habitat used by fishers (Pekania pennanti) has been relatively well studied but information on the persistence of their resting structures over time is unknown. We selected for reexamination 73 of 195 resting structures used by by fishers in northwestern California and compared their condition on the date they were found with their condition 8.2-12.1 years later. Resting structures were classified into three functional groups: live trees, snags, and logs. Each group was classified further into structural stages of decay or decomposition. A total of 19.2% of resting structures changed structural stage over the assessment period, transitioning from one structural stage to another within or between groups. However, none of the structures declined in function to the point that they could not be used for resting. One tree jumped two functional groups, transitioning from a live tree to a log. Based on the rates of degradation that we observed, we recommend monitoring the fate of fisher resting structures every few decades. This will help us provide information about the loss rate of resting structures that, when combined with new information about the rate of cavity creation in trees and snags, will help us determine whether the forces of resting structure loss and gain are in dynamic equilibrium.