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Old-growth forests harbor a large amount of complex structural features that result in a wide array of wildlife habitats. However, intensive forest management is gradually converting old-growth forest into younger, even-aged stands, reducing structural complexity and threatening the persistence of old-growth-dependent species. Maintaining elements of complex stand structure is critical to the conservation of old-growth forest specialists that use different habitat components at different periods of their annual cycle, and it requires a comprehensive understanding of seasonal variation in the habitat needs of these species. However, difficulties in observing free-ranging animals have sometimes limited our ability to assess such variations in habitat requirements, especially for small, elusive species. To address this, we used GPS telemetry collars to describe fine-scale habitat selection patterns of 6 male American Martens (Martes americana) during 2 contrasting periods of the year (snow-free, from mid-April to mid-November; snow-covered, from mid-November to mid-April), an objective formerly hard to achieve using conventional VHF telemetry. We used resource selection functions conducted at the fourth order of selection to compare habitat characteristics found at the sites used by martens (GPS locations, n = 100) to those found on an equal number of available sites (random points, n = 100) within each individual seasonal home range. We conducted vegetation surveys on these 200 sites to describe habitat and built candidate models representing different concurrent hypotheses. Our results showed that proxies of prey availability, predator avoidance, and thermal constraints were the primary factors influencing marten habitat selection during both periods, although their respective importance differed between periods. Martens selected sites with a high density of large-diameter snags (≥30·ha−1), high conifer canopy closure (≥53%), and a dense lateral cover (≥81%) during the snow-free period, but selected sites with a high volume of coarse woody debris (≥64 m3·ha−1) and high conifer canopy closure (≥48%) during the snow-covered period. Our results highlight the importance of contrasting seasonal changes in habitat selection patterns of small carnivores and may help maintain structural attributes in the landscape that are suitable for male American Martens. [ABSTRACT FROM AUTHOR]

In response to the striking effects of environmental change, conservation strategies often include the identification of conservation areas that can effectively maintain vulnerable species. Consequently, identifying system‐specific conditions that maintain the demographic and genetic viability of species of conservation concern is essential. Connectivity plays a critical role in the persistence of populations. Islands have been model systems to understand connectivity and metapopulation processes and have emerged as particularly favorable targets for conservation. While islands can be isolated from mainland disturbances, it is unknown what degree of isolation is necessary to avoid unfavorable changes but remain sufficiently connected to maintain population viability. To test this question, we explored connectivity within the Apostle Islands, an archipelago of 22 islands within Lake Superior, by comparing historical and contemporary trends in ice bridge connectivity and by simulating the effect of reduced connectivity within this system. We developed a demographically informed individual‐based model to explicitly test the role of connectivity to influence the persistence and genetic diversity of American marten Martes americana, a forest carnivore at risk across its southern range boundary. We found that genetic diversity was resilient to moderate changes in ice cover, but a complete loss of connectivity resulted in rapid genetic erosion. Despite genetic erosion, populations persisted as long as nominal connectivity occurred between islands. Our work suggests that connectivity will decline, but martens would be resilient to moderate changes and, in the short term, the Apostle Islands can act as a refuge along this species' southern range boundary. Identifying thresholds in connectivity that maintain populations but allow for isolation from disturbance will be necessary to identify suitable areas for species conservation across space and time. [ABSTRACT FROM AUTHOR]

Shifts in mean body size coinciding with environmental change are well documented across animal species and populations, serving as a widespread and complex indicator of climate-change response. In mammal research, identifying and disentangling the potential drivers of these trends (e.g. thermoregulation, resource availability) is hindered by treating adult size as fixed, ignoring morphological changes that occur throughout life in many species. However, observed population-level size trends may reflect underlying shifts in age structure (i.e. change in the proportion of older, potentially larger individuals in the population). Here, we assessed the role of age structure by explicitly evaluating age as a contributor to temporal variation in skull size (a proxy for body size) in 2 carnivorans, Canadian Lynx (Lynx canadensis) and American Marten (Martes americana). Using a series of linear and nonlinear models, we tested age in years (determined by cementum-layer analysis) as a predictor of skull size alongside other factors previously proposed to be important drivers of body-size trends, including population density for lynx and growing season conditions for martens. In both species, age was a significant predictor of skull size indicating a rapid year-to-year increase in young adult size that diminished in later adulthood. However, temporal shifts in age structure alone did not explain the observed changes in size over time, indicating that age structure acts in concert with other as-yet unidentified factors to drive body-size change. By explicitly evaluating the role of age, we can both refine models of temporal body-size trends and gain insights into size change as a signal of underlying demographic shifts—such as age-specific survivorship—providing a more holistic understanding of how mammals are responding to climate change. [ABSTRACT FROM AUTHOR]

Protected areas are essential tools for reducing loss of global biodiversity. To fulfill their ecological functions, protected areas must be connected to their surroundings, a requirement that is difficult to meet in landscapes intensively disturbed by anthropogenic activities. Therefore, protecting movement corridors at the edges of protected areas is crucial, especially for species with broad habitat needs, such as the American marten (Martes americana). However, habitat selection and space use patterns are dynamic processes, so we could expect that functional connectivity would vary temporally in response to changing environmental conditions and levels of human activities. In this study, we aimed at predicting the location of movement corridors for the American marten in Forillon National Park and its periphery during two contrasted periods (snow‐free: May–November; snow‐covered: December–April). We used "seasonal" resource selection functions to identify core areas (interpreted as circuit "nodes") and CircuitScape to delineate movement corridors between them based on the electrical circuit theory. Habitat selection patterns differed between periods, with martens avoiding open areas, high elevations and road proximity during the snow‐free period, while avoiding areas closer to secondary roads but selecting areas closer to primary roads and housing structures during the snow‐covered period. Consequently, the location of movement corridors differed partially between periods. Functional connectivity was favored by the presence of forest patches for both periods, while being constrained by open environments, especially during the snow‐free period. Our study highlights the importance of modeling functional connectivity at fine temporal scales in order to provide movement corridors that fulfill the requirements of a species at each period of its annual cycle. [ABSTRACT FROM AUTHOR]

Shifts in habitat selection may serve as behavioral indicators of changing habitat quality and can provide an insight into the effects of chronic disturbance on wildlife populations before rates of occurrence and other metrics related to population viability are affected. Long‐term studies can provide unique opportunities to understand animals' behavioral responses to the cumulative effects of habitat disturbance that may be missed by short‐term studies or space‐for‐time substitution. Using the American marten (Martes americana) as a focal species, we evaluated the effects of progressive habitat disturbance on an animal population by identifying changes in habitat availability and selection over time. Marten are strongly associated with mature forest conditions and are thus sensitive to forest harvesting, which is a chronic and prevalent form of disturbance across the species' range. We developed resource selection functions that characterized both temporally consistent patterns and functional responses in the relative selection of habitats by marten at the patch scale. We used a combination of marten location data collected during three periods over 30 years of extensive forest change in northern Maine and a habitat classification scheme informed by species' behavior and designed to capture habitat changes over time. Marten increased their selection of tall (>12 m mean tree height) mature forest, including uncut forest and regenerated clearcuts, in response to decreased availability. Marten also increased avoidance of early‐successional forest (<9 m mean tree height) in response to increased availability. These functional responses in habitat selection appear to enable marten to maintain access to required resources in mature forest and limit exposure to risky or resource‐poor habitat within home ranges. However, a declining trend in the occurrence of resident adult females may indicate a limit to the functional response strategies for individuals unable to incur the energetic or prey‐related costs that may be associated with strong functional responses. Our results suggest that, despite adaptive habitat selection strategies, there are minimum thresholds of mature forest availability below which resident adults, particularly females, will struggle to persist. We recommend forest management strategies targeted at minimizing the strength of functional responses displayed by marten within occupied landscapes. [ABSTRACT FROM AUTHOR]

Abstract Protected areas are essential tools for reducing loss of global biodiversity. To fulfill their ecological functions, protected areas must be connected to their surroundings, a requirement that is difficult to meet in landscapes intensively disturbed by anthropogenic activities. Therefore, protecting movement corridors at the edges of protected areas is crucial, especially for species with broad habitat needs, such as the American marten (Martes americana). However, habitat selection and space use patterns are dynamic processes, so we could expect that functional connectivity would vary temporally in response to changing environmental conditions and levels of human activities. In this study, we aimed at predicting the location of movement corridors for the American marten in Forillon National Park and its periphery during two contrasted periods (snow‐free: May–November; snow‐covered: December–April). We used “seasonal” resource selection functions to identify core areas (interpreted as circuit “nodes”) and CircuitScape to delineate movement corridors between them based on the electrical circuit theory. Habitat selection patterns differed between periods, with martens avoiding open areas, high elevations and road proximity during the snow‐free period, while avoiding areas closer to secondary roads but selecting areas closer to primary roads and housing structures during the snow‐covered period. Consequently, the location of movement corridors differed partially between periods. Functional connectivity was favored by the presence of forest patches for both periods, while being constrained by open environments, especially during the snow‐free period. Our study highlights the importance of modeling functional connectivity at fine temporal scales in order to provide movement corridors that fulfill the requirements of a species at each period of its annual cycle.

Competition shapes animal communities, but the strength of the interaction varies spatially depending on the availability and aggregation of resources and competitors. Among carnivores, competition is particularly pronounced with the strongest interactions between similar species with intermediate differences in body size. While ecologists have emphasized interference competition among carnivores based on dominance hierarchies from body size (smaller = subordinate; larger = dominant), the reciprocity of exploitative competition from subordinate species has been overlooked even though efficient exploitation can limit resource availability and influence foraging.Across North America, fishers Pekania pennanti and martens (Martes spp.) are two phylogenetically related forest carnivores that exhibit a high degree of overlap in habitat use and diet and differ in body size by a factor of 2–5×, eliciting particularly strong interspecific competition. In the Great Lakes region, fishers and martens occur both allopatrically and sympatrically; where they co‐occur, the numerically dominant species varies spatially. This natural variation in competitors and environmental conditions enables comparisons to understand how interference and exploitative competition alter dietary niche overlap and foraging strategies.We analysed stable isotopes (δ13C and δ15N) from 317 martens and 132 fishers, as well as dietary items (n = 629) from 20 different genera, to compare niche size and overlap. We then quantified individual diet specialization and modelled the response to environmental conditions that were hypothesized to influence individual foraging.Martens and fishers exhibited high overlap in both available and core isotopic δ‐space, but no overlap of core dietary proportions. When the competitor was absent or rare, both martens and fishers consumed more smaller‐bodied prey. Notably, the dominant fisher switched from being a specialist of larger to smaller prey in the absence of the subordinate marten. Environmental context also influenced dietary specialization: increasing land cover diversity and prey abundance reduced specialization in martens whereas vegetation productivity increased specialization for both martens and fishers.Despite an important dominance hierarchy, fishers adjusted their niche in the face of a subordinate, but superior, exploitative competitor. These findings highlight the underappreciated role of the subordinate competitor in shaping the dietary niche of a dominant competitor. [ABSTRACT FROM AUTHOR]

Context: For wildlife dependent on mature forest living in managed landscapes, habitat loss from land use can outpace habitat recovery from forest regrowth, challenging persistence of habitat specialists. For some species, the effects of habitat loss or fragmentation may also differ between sexes when physiological or behavioral differences influence space use. Objectives: We evaluated differences in landscape-scale occurrence, as a function of habitat amount and configuration, between male and female American martens in the heterogeneous, commercial forestlands of northern Maine, USA. Methods: Using location data from a long-term (1994–1997) radio-telemetry study, we modeled boundaries of home ranges occupied by resident adults (> 1 year) and simulated potential home ranges in unoccupied areas. Landscape metrics of habitat amount and configuration within home ranges, calculated from time-specific maps of suitable habitat derived from Landsat satellite imagery, were used to develop binary logistic regression models that were compared within an information theoretic framework. We extrapolated and tested top performing models in two novel landscapes. Results: Habitat amount was most important when predicting female occurrence. For males, which maintained larger home ranges, occurrence was influenced by habitat amount and patchiness (density and shape). Top sex-specific models reliably predicted marten occurrence (1991–1996) in an adjacent forest preserve, but overestimated occurrence, particularly for females, in a more distant (~ 70 km Northeast) commercial forest in 2007. Conclusions: Marten in our study exhibited nonlinear declines in occurrence as suitable habitat declined. Maintaining sufficient habitat to support adult females in particular will be important to the future conservation of this late breeding, area sensitive, habitat specialized species. [ABSTRACT FROM AUTHOR]

Ecological heterogeneity promotes species persistence and diversity. Environmental change has, however, eroded patterns of heterogeneity globally, stifling species recovery. To test the effects of seasonal heterogeneity on a reintroduced carnivore, American martens (Martes americana), we compared metrics of local and season-specific heterogeneity to traditional forest metrics on the survival of 242 individuals across 8 years and predicted a survival landscape for 13 reintroduction sites. We found that heterogeneity—created by forest structure in the growing season and snow in the winter—improved survival and outperformed traditional forest metrics. Spatial variation in heterogeneity created a distinct survival landscape, but seasonal change in heterogeneity generated temporal discordance. All translocation sites possessed high forest heterogeneity but there were greater differences in winter heterogeneity; recovery sites with the poorest snow conditions had the lowest viability. Our work links heterogeneity across seasons to fitness and suggests that management strategies that increase seasonal aspects of heterogeneity may help to recover other sensitive species to continuing environmental change. [ABSTRACT FROM AUTHOR]

Fisher (Pekania pennanti) is a medium-sized mesocarnivore that typically occupies mature hardwood and softwood forest where its preferred prey is abundant. In Nova Scotia, Fisher populations are reported as restricted to the mainland; they have been absent from Cape Breton Island for the past 50-80 years. A record of a Fisher on Cape Breton Island in February 2002 prompted us to collate and analyze other records of Cape Breton Island sightings of the species from that date to May 2021. Based on reported sightings, we conclude that Fisher has extended its range from mainland Nova Scotia, apparently crossing the Strait of Canso, and that a breeding population now exists on Cape Breton Island and is expanding. We also comment on possible negative interactions between this expanding Fisher population and the provincially Endangered American Marten (Martes americana) population on the island. [ABSTRACT FROM AUTHOR]

Species reintroductions are successful when established populations maintain both demographic stability and genetic diversity. Such a result may be obtained by ensuring both structural habitat connectivity and genetic connectivity among reintroduced and remnant populations. Nevertheless, prezygotic barriers such as assortative mating can prevent the flow of genetic material between populations, even when migration between populations is high. Limited gene flow may be particularly relevant for reintroductions that were sourced either from captive-bred populations or from disparate locations in the wild. American martens (Martes americana) have been reintroduced repeatedly in the Upper Midwestern United States in an effort to establish self-sustaining populations. We quantified levels of genetic diversity within and spatial genetic variance among four marten populations during two time periods separated by 10 years. Spatially informed and naïve discriminant analysis of principal components were used to assign individuals to populations. Results indicate that heterozygosity declined and inbreeding coefficients increased between the two collection periods, while genetic structure among populations also increased. Data are consistent with assortative mating contributing to reapportioning of genetic variation. Population assignment tests show that migration among populations is apparent, but admixture (based on cluster membership probabilities) is low and declined over time. Specifically, martens may be successfully dispersing between populations but a lack of admixture indicates a lack of reproductive contributions to genetic diversity by migrants. Because marten reintroductions in this region are well-documented and well-monitored, lessons can be derived from results to inform future reintroductions. We encourage a careful balance of supplementing genetic diversity via augmentation while avoiding translocation of animals from disparate populations that may result in reproductive isolation of migrants. In combination with the maintenance of a functionally connected landscape, this strategy would maximize the likelihood of a successful reintroduction in terms both of demography and genetics. [ABSTRACT FROM AUTHOR]

Human land use is a driving force of habitat loss and modification globally, with consequences for wildlife species. The American marten (Martes americana) and fisher (Pekania pennanti) are forest‐dependent carnivores native to North America. Both species suffered population declines due to loss of forested habitat and overharvest for furs, and continued habitat modification is an ongoing threat. Furthermore, the smaller marten may be susceptible to intraguild exclusion where the larger fisher are abundant, and both habitat modification and climate change may reduce spatial refugia available to marten. A detailed understanding of co‐occurrence patterns of marten and fisher in landscapes subjected to intense forest disturbance represents a key knowledge gap for wildlife ecology and management. Maine, in the northeastern United States, supports populations of both these species. It is an extensively forested state, and the vast majority is managed as commercial timberland. We designed a large‐scale field study to understand the relative importance of three sets of predictions for marten and fisher occupancy patterns where commercial silviculture is widespread: (1) The intensity of forest disturbance primarily determined both marten and fisher occupancy rates, (2) fisher occupancy was limited to areas of shallower snow and marten limited by fisher presence, or (3) both species responded to the composition of tree species within forested habitat. We collected data to test these nonmutually exclusive hypotheses via camera‐trap surveys, using an experimental design balanced across a gradient of forest disturbance intensity. We deployed 197 camera stations in both summer and winter over 3 years (2017–2020). We tagged over 800,000 images and found marten at 124 (63%) and fisher at 168 (85%) of the stations. By fitting multiseason occupancy models to the data, we found that the degree of habitat disturbance negatively influenced detection, occupancy, and temporal turnover for both species. Contrary to our expectations, however, we found no evidence of interspecific competition and instead support for positive associations with detection probabilities both spatially and temporally. Both species were positively associated with forest stands containing deciduous trees. Our findings further illustrate the impact that land use has on the occupancy dynamics for these forest‐dependent carnivores. [ABSTRACT FROM AUTHOR]

Abstract Human land use is a driving force of habitat loss and modification globally, with consequences for wildlife species. The American marten (Martes americana) and fisher (Pekania pennanti) are forest‐dependent carnivores native to North America. Both species suffered population declines due to loss of forested habitat and overharvest for furs, and continued habitat modification is an ongoing threat. Furthermore, the smaller marten may be susceptible to intraguild exclusion where the larger fisher are abundant, and both habitat modification and climate change may reduce spatial refugia available to marten. A detailed understanding of co‐occurrence patterns of marten and fisher in landscapes subjected to intense forest disturbance represents a key knowledge gap for wildlife ecology and management. Maine, in the northeastern United States, supports populations of both these species. It is an extensively forested state, and the vast majority is managed as commercial timberland. We designed a large‐scale field study to understand the relative importance of three sets of predictions for marten and fisher occupancy patterns where commercial silviculture is widespread: (1) The intensity of forest disturbance primarily determined both marten and fisher occupancy rates, (2) fisher occupancy was limited to areas of shallower snow and marten limited by fisher presence, or (3) both species responded to the composition of tree species within forested habitat. We collected data to test these nonmutually exclusive hypotheses via camera‐trap surveys, using an experimental design balanced across a gradient of forest disturbance intensity. We deployed 197 camera stations in both summer and winter over 3 years (2017–2020). We tagged over 800,000 images and found marten at 124 (63%) and fisher at 168 (85%) of the stations. By fitting multiseason occupancy models to the data, we found that the degree of habitat disturbance negatively influenced detection, occupancy, and temporal turnover for both species. Contrary to our expectations, however, we found no evidence of interspecific competition and instead support for positive associations with detection probabilities both spatially and temporally. Both species were positively associated with forest stands containing deciduous trees. Our findings further illustrate the impact that land use has on the occupancy dynamics for these forest‐dependent carnivores.

A Northern Goshawk (Accipiter gentilis) was observed following an American Marten (Martes americana). The marten's attempts to capture a Gray Squirrel (Sciurus carolinensis) forced the squirrel into the open where the goshawk repeatedly attempted to capture it as the marten chased it through the trees. Attacks on prey flushed by heterospecific predators have been reported for a few other raptors, but this type of interaction has not been reported previously for either goshawks or martens. [ABSTRACT FROM AUTHOR]

Rapid environmental change is reshaping ecosystems and driving species loss globally. Carnivore populations have declined and retracted rapidly and have been the target of numerous translocation projects. Success, however, is complicated when these efforts occur in novel ecosystems. Identifying refuges, locations that are resistant to environmental change, within a translocation framework should improve population recovery and persistence. American martens (Martes americana) are the most frequently translocated carnivore in North America. As elsewhere, martens were extirpated across much of the Great Lakes region by the 1930s and, despite multiple translocations beginning in the 1950s, martens remain of regional conservation concern. Surprisingly, martens were rediscovered in 2014 on the Apostle Islands of Lake Superior after a putative absence of >40 yr. To identify the source of martens to the islands and understand connectivity of the reintroduction network, we collected genetic data on martens from the archipelago and from all regional reintroduction sites. In total, we genotyped 483 individual martens, 43 of which inhabited the Apostle Islands (densities 0.42–1.46 km−2). Coalescent analyses supported the contemporary recolonization of the Apostle Islands with progenitors likely originating from Michigan, which were sourced from Ontario. We also identified movements by a first‐order relative between the Apostle Islands and the recovery network. We detected some regional gene flow, but in an unexpected direction: individuals moving from the islands to the mainland. Our findings suggest that the Apostle Islands were naturally recolonized by progeny of translocated individuals and now act as a source back to the reintroduction sites on the mainland. We suggest that the Apostle Islands, given its protection from disturbance, complex forest structure, and reduced carnivore competition, will act as a potential refuge for marten along their trailing range boundary and a central node for regional recovery. Our work reveals that translocations, even those occurring along southern range boundaries, can create recovery networks that function like natural metapopulations. Identifying refuges, locations that are resistant to environmental change, within these recovery networks can further improve species recovery, even within novel environments. Future translocation planning should a priori identify potential refuges and sources to improve short‐term recovery and long‐term persistence. [ABSTRACT FROM AUTHOR]

Several species of martens (Martes spp.) are reported to use buildings as resting or den sites. However, such behaviour has not been attributed to American Marten (Martes americana). We report American Marten using occupied buildings and evidence of suspected use of an abandoned cabin, as resting sites in southern Yukon, Canada. These observations further highlight the behavioural flexibility of North American species of Martes with regard to using novel structures as resting sites. [ABSTRACT FROM AUTHOR]

Human activities resulting in the extirpation of small carnivore populations -- either directly through shooting, trapping, or poisoning of the animals, or indirectly through the control of prey or habitat destruction -- have repeated themselves over space and time. Since the early 1900s, pest control methods in the Canadian Prairies and habitat loss and deterioration in the northern forests negatively affected and continue to alter small carnivore communities. Typically, for decades industry has taken the same approach in control of vertebrate pests and obtained meagre results that affected negatively small carnivores. The reduction of Richardson's ground squirrel, Urocitellus richardsonii, and northern pocket gopher, Thomomys talpoides, populations to density levels that do not cause significant losses to crop productivity is the solution. A properly developed Integrated Pest Management programme, with detailed information about when and how to use specific control methods, and protocols to follow to avoid non-target and secondary poisoning, can meet the needs of both conservationists and farmers. Timber harvesting has produced landscapes that failed to meet the ecological needs of small carnivores such as the American marten, Martes americana, and the fisher, Pekania pennanti. In central interior British Columbia, to compensate a forestry company for increased habitat conservation in parts of its forest management area, timber harvest was increased in forests with lower biodiversity potential that were adjacent to 2 conservation areas. The resulting forest management plan was a win--win solution for conservationists and foresters. We need to change our response to human--small carnivore conflicts or we will face continued erosion of small carnivore populations and alteration of the ecosystems to which they contribute. In a world where economics generally dominate management decisions, wildlife biologists must link the benefits and costs of small carnivore conservation with those of human societies and activities. The involvement of wildlife biologists in small carnivore conservation programmes must be pragmatic, and conservation programmes must be based on solid field-based datasets. [ABSTRACT FROM AUTHOR]

North American martens are forest dependent, influenced by human activity, and climate vulnerable. They have long been managed and harvested throughout their range as the American marten (Martes americana). Recent work has expanded evidence for the original description of two species in North America — M. americana and the Pacific Coast marten, M. caurina — but the geographic boundary between these groups has not been described in detail. From 2010 to 2016 we deployed 734 multi-taxa winter bait stations across a 53,474 km2 study area spanning seven mountain ranges within the anticipated contact zone along the border of Canada and the United States. We collected marten hair samples and developed genotypes for 15 polymorphic microsatellite loci for 235 individuals, and 493 base-pair sequences of the mtDNA gene COI for 175 of those individuals. Both nuclear and mitochondrial genetic structure identified a sharp break across the Clark Fork Valley, United States with M. americana and M. caurina occurring north and south of the break, respectively. We estimated global effective population size (Ne) for each mountain range, clinal genetic neighborhood sizes (NS), calculated observed (Ho) and expected (He) heterozygosity, fixation index (FST), and clinal measures of allelic richness (Ar), Ho, and inbreeding coefficient (FIS). Despite substantial genetic structure, we detected hybridization along the fracture zone with both contemporary (nuclear DNA) and historic (mtDNA) gene flow. Marten populations in our study area are highly structured and the break across the fracture zone being the largest documented in North America (FST range 0.21–0.34, mean = 0.27). With the exception of the Coeur d’Alene Mountains, marten were well distributed across higher elevation portions of our sampling area. Clinal NS values were variable suggesting substantial heterogeneity in marten density and movement. For both M. americana and M. caurina, elevationaly dependent gene flow and high genetic population structure suggest that connectivity corridors will be important to ensuring long-term population persistence. Our study is an example of how a combination of global and clinal molecular data analyses can provide important information for natural resource management.

Martens (Martes spp.) occupy areas with complex forest structure that can exhibit patchy distribution, particularly in managed forest landscapes. These structures (e.g., downed wood) are often difficult to reliably sample so more easily acquired surrogates may better describe marten habitat. Recent advances in global positioning system (GPS) collars combined with integrated (i.e., imagery with geospatial modeling), resolute, remotely sensed maps offer a potentially efficient means of understanding marten space use. We placed GPS collars on 13 American marten (M. americana), attempted to acquire a locational fix every 15 min, and calculated adaptive kernel home ranges from successful locations. We modeled probability of marten use as a function of covariates derived from remotely sensed data that included proportion of vegetation cover types, and distances to maintained roads and hydrographic features at 2.5, 4.5, and 7.1 ha extents. Average cover type values varied minimally across spatial extents we evaluated, indicating fine-scale homogenization. Amount of tall (> 10 m) deciduous forest, tall and short conifer forests, and riparian forests had positive effects on marten use, whereas distance to maintained roads had a weak negative effect. Broad riparian areas (e.g., scrub–shrub swamps that occur in broad topographic depressions), not necessarily associated with mapped hydrographic lines, were heavily used by marten. We found that core use areas for marten could reliably be predicted from 30 m remotely sensed maps summarized at relatively small extents (2.4–7.1 ha). [ABSTRACT FROM AUTHOR]

Context: Functional landscape connectivity is vital for the conservation of wildlife species. Landscape connectivity models often overlook factors such as mortality and asymmetry in landscape resistance that can have a significant impact on functional connectivity. Individual-based models (IBMs) can be used to explore such factors through the implementation of mechanistic dispersal behavior. Furthermore, population-level patterns of animal dispersal and landscape connectivity resulting from the simulation of alternative landscapes or scenarios of animal behavior can be compared. Objectives: Use an IBM to evaluate the effects of disperser mortality, asymmetrical dispersal due to landscape structure, and land-use change on the functional landscape connectivity between two populations of reintroduced American martens Martes americana. Methods: We applied a previously calibrated IBM of marten dispersal to simulate movement between two reintroduced populations in Wisconsin and Michigan, USA. We used machine learning analyses to determine how each factor affected dispersal between populations (connectivity) across five consecutive generations. Results: Functional landscape connectivity between populations was not always correlated with more traditional dispersal metrics, such as dispersal distance. Mortality had the greatest impact on functional connectivity. Land-use change and landscape configuration affected connectivity mostly when mortality was not incorporated into simulations. These experimental factors had a stronger effect on long-distance dispersal between populations than on more local dispersal. Conclusions: Conservation planning for landscape connectivity may benefit from accounting for mortality risks within matrix habitat. The development of individual-based models that incorporate landscape heterogeneity and complex animal behaviors when investigating long-distance dispersal can provide unique and specific insights into both landscape connectivity and wildlife conservation. [ABSTRACT FROM AUTHOR]

Context: Interspecific competition can limit species distributions unless competitors partition niche space to enable coexistence. Landscape heterogeneity can facilitate niche partitioning and enable coexistence, but land-use change is restructuring terrestrial ecosystems globally with unknown consequences for species interactions. Objectives: We tested the relationship between landscape heterogeneity and carnivore co-occurrence in natural and human-dominated ecosystems to assess the landscape-mediated impacts of anthropogenic change on coexistence. Methods: We used boosted regression trees to model the distributions and co-occurrence of two competing forest carnivores, American martens and fishers, at two contrasting sites in the Great Lakes region, USA: a "natural" site largely devoid of human impacts and a "human-dominated" site with substantial development and a history of land-use change. We assessed the importance of climate and habitat variables for each species, measured spatial niche overlap, and quantified co-occurrence as a function of compositional (patch richness), configurational (landscape shape), and topographical (elevation range) heterogeneity per site. Results: We observed significant differences in the effect of heterogeneity on co-occurrence between sites. The natural landscape exhibited little niche overlap and co-occurrence had a significant, positive relationship with heterogeneity. Conversely, the human-dominated site exhibited high niche overlap with variable effects of heterogeneity on co-occurrence. Elevation, snowpack, and development had strong, contrasting effects on marten and fisher distributions, suggesting that differential use of habitat and anthropogenic features facilitates coexistence. Conclusions: Heterogeneity can facilitate coexistence, but too much may undermine carnivore coexistence in human-dominated landscapes where habitat and space are limited. Moreover, future climate change will likely erode niche partitioning among martens and fishers, with particularly strong consequences for coexistence in human-dominated landscapes and at range boundaries. [ABSTRACT FROM AUTHOR]

North American martens are forest dependent, influenced by human activity, and climate vulnerable. They have long been managed and harvested throughout their range as the American marten (Martes americana). Recent work has expanded evidence for the original description of two species in North America — M. americana and the Pacific Coast marten, M. caurina — but the geographic boundary between these groups has not been described in detail. From 2010 to 2016 we deployed 734 multi-taxa winter bait stations across a 53,474 km2 study area spanning seven mountain ranges within the anticipated contact zone along the border of Canada and the United States. We collected marten hair samples and developed genotypes for 15 polymorphic microsatellite loci for 235 individuals, and 493 base-pair sequences of the mtDNA gene COI for 175 of those individuals. Both nuclear and mitochondrial genetic structure identified a sharp break across the Clark Fork Valley, United States with M. americana and M. caurina occurring north and south of the break, respectively. We estimated global effective population size (N e ) for each mountain range, clinal genetic neighborhood sizes (NS), calculated observed (H o ) and expected (H e ) heterozygosity, fixation index (F ST ), and clinal measures of allelic richness (Ar), H o , and inbreeding coefficient (F IS ). Despite substantial genetic structure, we detected hybridization along the fracture zone with both contemporary (nuclear DNA) and historic (mtDNA) gene flow. Marten populations in our study area are highly structured and the break across the fracture zone being the largest documented in North America (F ST range 0.21–0.34, mean = 0.27). With the exception of the Coeur d'Alene Mountains, marten were well distributed across higher elevation portions of our sampling area. Clinal NS values were variable suggesting substantial heterogeneity in marten density and movement. For both M. americana and M. caurina , elevationaly dependent gene flow and high genetic population structure suggest that connectivity corridors will be important to ensuring long-term population persistence. Our study is an example of how a combination of global and clinal molecular data analyses can provide important information for natural resource management. [ABSTRACT FROM AUTHOR]

Studies that assess mercury bioaccumulation in small carnivores in terrestrial habitats are limited. We quantified total mercury (THg) in American marten (Martes americana) that were harvested for fur in Michigan, US, during 2013 and 2014. We quantified THg (dry weight) in hair, kidney, and liver samples and further analyzed hair for potential demographic and ecological factors that influence THg bioaccumulation. We found THg concentrations to be the highest in hair (1.228±0.475 µg/g, n=40), followed by kidney (0.922±0.651 µg/g, n=29) and liver (0.344±0.219 µg/g, n=26). Total mercury distributed predictably and significantly between tissue types, and hair was moderately predictive at modeling THg in kidney (R2=0.50, P<0.001, n=29) and weakly predictive in liver (R2=0.35, P<0.001, n=26), suggesting that hair, which is easily obtained, could be a useful sample type for future biomonitoring programs. The concentrations of THg in hair were higher in adults relative to juveniles, and adult female martens had the highest levels of THg (1.980±0.188 µg/g), as compared to juveniles and adult males. Results of generalized linear modeling suggested that THg hair concentrations were positively associated with marten age and trophic position (stable isotope ratio, δ15N). An interaction between δ15N and the year marten carcasses were collected showed that δ15N alone could be highly predictive of THg in some years but not in others. Annual changes in diet could lead to differing rates of mercury bioaccumulation and alter the usefulness of δ15N to predict THg in marten tissues. Further research should explore the connections between changes in prey availability, types of prey consumed, and the influence on bioaccumulation rates of mercury in terrestrial system mesocarnivores. [ABSTRACT FROM AUTHOR]

ABSTRACT Snow‐tracking is important for elucidating patterns of carnivore behavior, but misclassifying tracks reduces the accuracy of snow‐tracking studies. Quantitative methods improve accuracy by distinguishing between similar tracks left by different carnivores. American marten (Martes americana) and fisher (Pekania pennanti) tracks are difficult to distinguish. We studied martens and fishers in northern Wisconsin, USA, during winter 2008–2010, to determine whether dimensions of tracks left in snow differed by snow conditions, and if marten and fisher tracks could be accurately classified by analyzing track dimensions that controlled for snow conditions. Snow depth, snow compaction, and crust depth correlated strongly with fisher step depth. Classification trees accurately classified marten and fisher tracks, and were 5–14% more accurate when track dimensions controlled for snow conditions. Species‐only classifications were 91–96% accurate. Trees that classified sex and species were 75–89% accurate, indicating that snow‐tracking can be used to estimate sex‐specific marten and fisher habitat selection, distribution, and abundance. Controlling for snow conditions improves track classification accuracy for martens and fishers, and would likely improve classification accuracy for other carnivores. © 2017 The Wildlife Society.

Selective pressures (i.e. resource limitation and competitive interaction) that drive the composition of ecological communities vary, and often operate on different ecological scales (ecological variables across varying spatial scales) than observed patterns. We studied the drivers of distribution and abundance of the American marten (Martes americana) and the carnivore community at three ecological scales on a Great Lakes island archipelago using camera traps. We found different drivers appeared important at each ecological scale and studying any of the three scales alone would give a biased understanding of the process driving the system. Island biogeography (resource limitation) was most important for carnivore richness, with higher richness on larger islands and lower richness as distance from the mainland increased. Marten presence on individual islands appeared to be driven by island size (resource limitation) and human avoidance (competitive interaction). Marten abundance at camera trap sites was driven by the cascading effect of coyotes (Canis latrans) on fishers (Pekania pennanti) (competitive interaction). Incorporating three ecological scales gave novel insights into the varying effects of resource limitation and competitive interaction processes. Our data suggests that ecological communities are structured through multiple competing ecological forces, and effective management and conservation relies on our ability to understand ecological forces operating at multiple ecological scales. [ABSTRACT FROM AUTHOR]

Intraguild (IG) interactions are common among mammalian carnivores, can include intraguild predation (IGP) and interspecific killing (IK), and are often asymmetrical, where a larger more dominant species (IGpredator) kills a smaller one (IGprey). According to ecological theory, the potential for an IGpredator and IGprey to coexist depends on whether the direct consumptive benefits for the IGpredator are substantial (IGP) or insignificant (IK), the extent to which the IGprey is the superior exploitative competitor on shared prey resources, and overall ecosystem productivity.We used resource selection models and spatially explicit age and harvest data for two closely related mesopredators that engage in IG interactions, American martens (Martes americana; IGprey) and fishers (Pekania pennanti; IGpredator), to identify drivers of distributions, delineate areas of sympatry and allopatry, and explore the role of an apex predator (coyote; Canis latrans) on these interactions.Model selection revealed that fisher use of this landscape was strongly influenced by late winter abiotic conditions, but other bottom‐up (forest composition) and top‐down (coyote abundance) factors also influenced their distribution. Overall, fisher probability of use was higher where late winter temperatures were warmer, snowpack was deeper, and measures of productivity were greater. Martens were constrained to areas of the landscape where the probability of fisher use, coyote abundance, and productivity were low and selected for forest conditions that presumably maximized prey availability. Marten age data indicated an increased proportion of juveniles outside of the predicted area of sympatry, suggesting that few animals survived >1.5 years in this area that supported higher densities of fishers and coyotes.Consistent with asymmetrical IG interaction theory, the IGpredator (fishers and, to a lesser degree, coyotes) competitively excluded the IGprey (martens) from more productive, milder temperature habitats, whereas IGpredators and IGprey coexisted in low productivity environments, where a combination of abiotic and biotic conditions enabled the IGprey to be the superior exploitative competitor. [ABSTRACT FROM AUTHOR]

Highlights • Between 1990 and 2015, good quality habitat for marten decreased from 20 to 13%. • Capture success decreased with increasing poor quality habitat. • Capture success is better where snowfall is higher. • Current logging techniques are detrimental to martens in the heart of their range. Abstract Over the last decades, timber harvest has greatly reduced the quality of habitat for several species. To mitigate this problem, government authorities often try to support silvicultural practices that help forests recover faster to a natural state while supporting the economic development of forestry. The American marten is a carnivore species that is sensitive to forest disturbances, which is one of the main factors limiting its populations. For several years, trappers have warned that logging reduced the abundance of marten in several areas at the heart of its distribution. We used forest inventories and trapping effort on traplines collected by the Quebec government since 1970 to assess the relationship between habitat quality, capture success of marten and weather over a 25 years span in Quebec. Our results showed that the abundance of marten decreased, following the proportion of good quality habitat since 1990. Furthermore, we observed an increase in capture success with the amount of snowfall suggesting that marten are more numerous in habitats where snow is abundant as it gives them a competitive advantage over sympatric mesocarnivores such as fishers. Consequently, as climate models forecast less snow in the future, the negative effect of logging could be amplified for this species. Forest planning should consider marten needs and improve the quality and connectivity of habitats to ensure the persistence of the American marten with changing climate. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of coexistence between ecologically similar species is an important issue in ecology. Carnivore coexistence may be facilitated by spatial segregation, temporal avoidance, and differential habitat selection. American martens Martes americana and fishers Pekania pennanti are medium‐sized mustelids that occur sympatrically across portions of North America, yet mechanisms of coexistence between the two species are not fully understood. We assessed spatial and temporal partitioning in martens and fishers in the Upper Peninsula of Michigan, USA, using camera trap data collected during winter 2013–2015. To investigate spatial segregation, we used a dynamic occupancy model to estimate species' occupancy probabilities and probabilities of persistence and colonization as a function of covariates and yearly occupancy probability for the other species. Temporal segregation was assessed by estimating diel activity overlap between species. We found weak evidence of spatial or temporal niche partitioning of martens and fishers. There was high overlap in forest cover selection, and both marten and fisher occupancy were positively correlated with deciduous forests (excluding aspen [Populus tremuloides]). There was strong temporal overlap (Δ^4=0.81; CI = 0.79–0.82) with both species exhibiting largely crepuscular activity patterns. Co‐occurrence of martens and fishers appears to be facilitated by mechanisms not investigated in this study, such as partitioning of snow features or diet. Our results add additional insights into resource partitioning of mesocarnivores, but further research is required to enhance our understanding of mechanisms that facilitate marten and fisher coexistence. [ABSTRACT FROM AUTHOR]

Reintroductions are frequently conducted to restore carnivore populations, though many fail despite following best management practices. Although demographic approaches are increasingly used to assess reintroduced populations, immigration is often overlooked in reintroduction planning and assessment. American martens (Martes americana) were reintroduced to 2 sites in Wisconsin, the Nicolet and Chequamegon national forests, which have anecdotally experienced differential population recovery. Via non‐invasive sampling and a mark‐recapture framework, we explored the possible mechanisms behind the divergent trajectories of the Nicolet National Forest (Nicolet) population, which appears to be recovering, and the Chequamegon National Forest (Chequamegon) population, which appears to be declining toward extinction. We tested for site‐level differences in survival, estimated population size, and calculated immigration rates based on simulations of the original reintroductions to the Nicolet. We then projected each population forward, both with and without our estimated immigration rate. We calculated a current population size of 66 female martens in the Nicolet, and estimated that the reintroduced population would have reached this size if supplemented by 1 female immigrant per year. We simulated future populations with the estimate of 1 female immigrant per year; this sustained level of immigration to the Nicolet reduced the probability of extinction to <1% over the next 100 years. When we applied the same rate of immigration to the starting population of 22 female martens in the Chequamegon, extinction probabilities were reduced by approximately 30%. Despite similarities between the 2 reintroduction sites, we propose that the differential population recovery was primarily due to modest rates of immigration to the Nicolet and the relative isolation of the Chequamegon population. Martens in the Chequamegon have been projected to go extinct in the foreseeable future, yet increasing connectivity with the Nicolet or Upper Peninsula of Michigan could improve persistence. Our results illustrate the effect of modest immigration on reintroduction success and the importance of planning for connectivity across reintroduction sites. © 2019 The Wildlife Society. American martens have experienced differential recovery at 2 reintroduction sites in Wisconsin; our work indicates that natural immigration is driving these divergent population trajectories. [ABSTRACT FROM AUTHOR]

Patterns of dispersal behavior are often driven by the composition and configuration of suitable habitat in a matrix of unsuitable habitat. Interactions between animal behavior and landscapes can therefore influence population dynamics, population and species distributions, population genetic structure, and the evolution of behavior. Spatially explicit individual-based models (IBMs) are ideal tools for exploring the effects of landscape structure on dispersal. We developed an empirically parameterized IBM in the modeling framework SEARCH to simulate dispersal of translocated American martens in Wisconsin. We tested the hypothesis that a time-limited disperser should be willing to settle in lower quality habitat over time. To evaluate model performance, we used a pattern-oriented modeling approach. Our best model matched all empirical dispersal patterns (e.g. dispersal distance) except time to settlement. This model incorporated a required search phase as well as the mechanism for declining habitat selectivity over time, which represents the first demonstration of this hypothesis for a vertebrate species. We suggest that temporal plasticity in habitat selectivity allows individuals to maximize fitness by making a tradeoff between habitat quality and risk of mortality. Our IBM is pragmatic in that it addresses a management need for a species of conservation concern. However, our model is also paradigmatic in that we explicitly tested a theory of dispersal behavior. Linking these 2 approaches to ecological modeling can further the utility of individual-based modeling and provide direction for future theoretical and empirical work on animal behavior. [ABSTRACT FROM AUTHOR]

ABSTRACT Remote telemetry data loggers are commonly used for monitoring wildlife species. Although remote telemetry data loggers provide reliable microhabitat use data, few studies have used them to evaluate landscape‐scale, temporal, and spatial habitat use. We installed 3 data loggers along a mountain ridgeline that was being developed for a commercial wind farm in northern New Hampshire, USA, to monitor use of a high‐elevation forest by American martens (Martes americana). We tested 1) the efficacy of data loggers to record presence–absence and index space use in a 6.75‐km2 area, validating marten locations using radiotelemetry and camera traps; and 2) whether there were diel and seasonal biases of data logger detections. As a case study, we evaluated temporal and spatial habitat‐use hypotheses with respect to variations in vegetation cover (leaf‐on or leaf‐off) and astronomical seasons using data from 11 martens monitored for nearly 2 years (6 Feb 2011–23 Dec 2012). Data loggers recorded presence–absence of radiocollared martens across 80% (240 of 299) of the trials within the study area with few false positives (4%; 19 of 494 trials). Detection probability and spatial use were most influenced by elevation, distance to data loggers, and line‐of‐sight view. We did not detect a seasonal bias but data loggers recorded fewer nocturnal detections. We recorded 118,120 detections of radiocollared martens, most of which occurred during leaf‐off seasons (87%; 102,931). Spatial use declined significantly (β = −0.54, P = 0.04) during the first leaf‐on season, corresponding with the construction phase of the wind farm project, and remained lower throughout the study. Diel use was explained by an astronomical calendar with greater nocturnal use during autumn and winter. Our results show that remote telemetry data loggers provided accurate spatiotemporal data for landscape‐scale habitat monitoring, overcoming many of the problems with telemetry data—such as limited sampling period and bias—that can compromise measurements of space use. We suggest incorporating remote telemetry data loggers for space use and disturbance studies of wildlife species. © 2016 The Wildlife Society.

Pacific martens (Martes caurina humboldtensis) in coastal forests of Oregon and northern California in the United States are rare and geographically isolated, prompting a petition for listing under the Endangered Species Act. If listed, regulations have the potential to influence land-use decisions on public and private lands, but no estimates of population size, density, or viability of remnant marten populations are available for evaluating their conservation status. We used GPS and VHF telemetry and spatial mark-resight to estimate home ranges, density, and population size of Pacific martens in the Oregon Dunes National Recreation Area, central coast Oregon, USA. We then estimated population viability at differing levels of human-caused mortality (e.g., vehicle mortality). Marten home ranges were small on average (females = 0.8 km2, males 1.5 km2) and density (1.13 martens/1 km2) was the highest reported for North American populations (M. caurina, M. americana). We estimated 71 adult martens (95% CRI [41–87]) across two subpopulations separated by a large barrier (Umpqua River). Using population viability analysis, extinction risk for a subpopulation of 30 martens, approximately the size of the subpopulation south of the Umpqua River, ranged from 32% to 99% with two or three annual human-caused mortalities within 30 years. Absent population expansion, limiting human-caused mortalities will likely have the greatest conservation impact.

Abstract Estimating population size and resource selection functions (RSFs) are common approaches in applied ecology for addressing wildlife conservation and management objectives. Traditionally such approaches have been undertaken separately with different sources of data. Spatial capture–recapture (SCR) provides a hierarchical framework for jointly estimating density and multi‐scale resource selection, and data integration techniques provide opportunities for improving inferences from SCR models. Despite the added benefits, there have been few applications of SCR‐RSF integration, potentially due to complexities of specifying and fitting such models. Here, we extend a previous integrated SCR‐RSF model to accommodate overlap of individuals between data sources and add the functionality to an open‐source R package (oSCR). We illustrate an application of the integrated model to a population of American marten (Martes americana) in alpine forests of northern New England. Spatial encounter data from camera traps were combined with telemetry locations from radio‐collared individuals to examine how density and space use varied with spatial environmental features. We compared multi‐model inferences between the integrated SCR‐RSF model with telemetry and a standard SCR model with no telemetry. The integrated SCR‐RSF model supported more complex relationships with spatial variation in third‐order resource selection (i.e., individual space use), including selection for areas with shorter distances to mixed conifer forest and rugged terrain. Both models indicated increased second‐order selection (i.e., density) for areas close to mixed conifer forest, while the integrated SCR‐RSF model had a lower effect size due to modulation from spatial variability in space use. Our application of the integrated SCR‐RSF model illustrates the improved inferences from spatial encounter data that can be achieved from integrating auxiliary telemetry data. Integrated modeling allows ecologists to join empirical data to ecological theory using a robust quantitative framework to better address conservation and management objectives.

ABSTRACT Global Positioning System (GPS) units used in animal telemetry often suffer from nonrandom data loss and location error. GPS units use stored satellite information to estimate locations, including almanac and ephemeris data reflecting satellite positions at weekly and at

The American marten Martes americana is a species of conservation concern in the northeastern United States due to widespread declines from over‐harvesting and habitat loss. Little information exists on current marten distribution and how landscape characteristics shape patterns of occupancy across the region, which could help develop effective recovery strategies. The rarity of marten and lack of historical distribution records are also problematic for region‐wide conservation planning. Expert opinion can provide a source of information for estimating species–landscape relationships and is especially useful when empirical data are sparse. We created a survey to elicit expert opinion and build a model that describes marten occupancy in the northeastern United States as a function of landscape conditions. We elicited opinions from 18 marten experts that included wildlife managers, trappers and researchers. Each expert estimated occupancy probability at 30 sites in their geographic region of expertise. We, then, fit the response data with a set of 58 models that incorporated the effects of covariates related to forest characteristics, climate, anthropogenic impacts and competition at two spatial scales (1.5 and 5 km radii), and used model selection techniques to determine the best model in the set. Three top models had strong empirical support, which we model averaged based on AIC weights. The final model included effects of five covariates at the 5‐km scale: percent canopy cover (positive), percent spruce‐fir land cover (positive), winter temperature (negative), elevation (positive) and road density (negative). A receiver operating characteristic curve indicated that the model performed well based on recent occurrence records. We mapped distribution across the region and used circuit theory to estimate movement corridors between isolated core populations. The results demonstrate the effectiveness of expert‐opinion data at modeling occupancy for rare species and provide tools for planning marten recovery in the northeastern United States. American marten occupancy was estimated across the northeastern United States from expert‐opinion data using mixed‐effects modeling techniques. Top‐performing models included predictor variables of tree canopy cover, spruce‐fir land cover, elevation, temperature and road density. In our expert survey, experts with primarily field‐based expertise made higher site‐occupancy estimates than experts with literature‐based expertise. [ABSTRACT FROM AUTHOR]

One of the continuing challenges in wildlife ecology and management is the ability to obtain reliable estimates of species' distributions at large spatial extents. Multi-scale occupancy models using a cluster sampling design offer the opportunity to increase the resolution of estimates and model processes occurring at multiple spatial scales, increasing the efficiency of large-scale monitoring and mitigating the tradeoff between extent and grain. However, accounting for spatial correlation among subsamples in a way that allows for the addition of covariates remains an issue. Using tracking transect surveys for carnivores as an example, we describe and evaluate a hierarchical, multi-scale occupancy model that integrates existing approaches to estimate occupancy at multiple spatial scales simultaneously, and uses a conditional autoregressive (CAR) process to account for spatial correlation in use between subsamples. We evaluated 3 versions of the model under a single-survey and a multi-survey sampling design: a non-spatial model, amodel that accounted for spatial correlation in use between transect segments, and a model that also accounted for spatial correlation in the detection process. Simulations showed that accounting for spatial correlation gave better estimates of transect-level occupancy under both sampling designs, whereas accurate estimates of segment-level use required a multi-survey design. When applied to historical snow track data, the differences in estimates among models followed the same pattern found in the simulations. The multi-survey design was able to detect equivalent declines in segment use with much less survey effort than the single-survey design. The modeling framework presented here offers researchers and managers a powerful tool for monitoring populations at large spatial extents while being able to detect ecologically important dynamics at finer spatial scales. [ABSTRACT FROM AUTHOR]

To better understand the clinical pathology, diseases, and causes of mortality of reintroduced American martens (Martes americana) in Michigan, a study was conducted from 2011 to 2015 in the Upper and Lower Peninsulas of Michigan. Samples obtained from live trapping (n=58) or harvested carcasses (n = 34) were serologically tested for select pathogens. Antibodies against Toxoplasma gondii and canine distemper virus were detected in 58 and 3.4% of samples, respectively. All samples were seronegative for Leptospira spp. and negative for Dirofilaria immitis antigen. Urine samples tested for Leptospira spp. via immunofluorescent antibody assay (n= 7), polymerase chain reaction (n=6), or both (n=3) were all negative. Parvovirus DNAwas detected in 9.1% of small intestine samples (n = 22) collected from carcasses and in 3.7% of fecal samples (n = 27) collected during live trapping. Complete blood counts (n = 64) and serum biochemistries (n = 63) were obtained from 49 live-trapped martens. Biochemical parameters found to be significantly different (P< 0.05) between genders were calcium, creatinine, glucose, and phosphorus. There was no significant difference between genders for any hematologic parameter. Significant differences (P< 0.05) between summer and winter seasons were found in total estimated white blood cell count, neutrophils, lymphocytes, monocytes, alkaline phosphatase, bicarbonate, calcium, creatinine, globulin, glucose, phosphorus, potassium, sodium, and total protein. There was no significant difference in blood cell count or serum biochemistry values between radio-collared (n = 17) and noncollared (n = 47) martens. Animals seropositive for T. gondii were found to have significantly higher (P< 0.05) eosinophil and globulin levels than seronegative animals. The primary natural cause for mortality of radio-collared American martens was predation. Histologic examinations revealed a high percentage (60%) of martens with verminous or granulomatous pneumonia. [ABSTRACT FROM AUTHOR]

Pacific martens (Martes caurina humboldtensis) in coastal forests of Oregon and northern California in the United States are rare and geographically isolated, prompting a petition for listing under the Endangered Species Act. If listed, regulations have the potential to influence land-use decisions on public and private lands, but no estimates of population size, density, or viability of remnant marten populations are available for evaluating their conservation status. We used GPS and VHF telemetry and spatial mark-resight to estimate home ranges, density, and population size of Pacific martens in the Oregon Dunes National Recreation Area, central coast Oregon, USA. We then estimated population viability at differing levels of human-caused mortality (e.g., vehicle mortality). Marten home ranges were small on average (females = 0.8 km², males 1.5 km²) and density (1.13 martens/1 km²) was the highest reported for North American populations (M. caurina, M. americana). We estimated 71 adult martens (95% CRI [41-87]) across two subpopulations separated by a large barrier (Umpqua River). Using population viability analysis, extinction risk for a subpopulation of 30 martens, approximately the size of the subpopulation south of the Umpqua River, ranged from 32% to 99% with two or three annual human-caused mortalities within 30 years. Absent population expansion, limiting human-caused mortalities will likely have the greatest conservation impact. [ABSTRACT FROM AUTHOR]

Reintroductions are an important conservation and management technique used to restore extirpated populations. Negative genetic consequences (e.g., diversity loss, bottlenecks, inbreeding) are often an unintentional result of reintroductions, due to a small number of founders or suboptimal habitat at release sites. American martens (Martes americana) were extirpated from Michigan's Lower Peninsula in 1911 due to habitat loss and unregulated trapping. Martens were reintroduced into 2 areas of the Lower Peninsula in 1985-1986. The Lower Peninsula reintroduction was characterized by a relatively small number of founders (85 individuals) released into 2 geographically disparate, fragmented sites. We genotyped martens sampled at the 2 release sites approximately 20-25 years since reintroduction, using 11 microsatellite loci. We detected low average allelic richness (3.92 alleles per locus), moderate levels of inbreeding (mean FIS = 0.106) and multiple loci with significant heterozygote deficiencies. Effective population size estimates were small, ranging between 6 and 27 individuals depending on the estimator and the sample group. We also detected significant population structuring between the release sites (FST = 0.093 using the most recent sample). With small population size and limited to no gene flow, we predict the 2 Lower Peninsula marten populations will continue to diverge and potentially further lose genetic diversity. This study highlights the importance of long-term genetic monitoring of reintroduced populations. [ABSTRACT FROM AUTHOR]

It is common to use multiple field sampling methods when implementing wildlife surveys to compare method efficacy or cost efficiency, integrate distinct pieces of information provided by separate methods, or evaluate method-specific biases and misclassification error. Existing models that combine information from multiple field methods or sampling devices permit rigorous comparison of method-specific detection parameters, enable estimation of additional parameters such as false-positive detection probability, and improve occurrence or abundance estimates, but with the assumption that the separate sampling methods produce detections independently of one another. This assumption is tenuous if methods are paired or deployed in close proximity simultaneously, a common practice that reduces the additional effort required to implement multiple methods and reduces the risk that differences between method-specific detection parameters are confounded by other environmental factors. We develop occupancy and spatial capture-recapture models that permit covariance between the detections produced by different methods, use simulation to compare estimator performance of the new models to models assuming independence, and provide an empirical application based on American marten ( Martes americana) surveys using paired remote cameras, hair catches, and snow tracking. Simulation results indicate existing models that assume that methods independently detect organisms produce biased parameter estimates and substantially understate estimate uncertainty when this assumption is violated, while our reformulated models are robust to either methodological independence or covariance. Empirical results suggested that remote cameras and snow tracking had comparable probability of detecting present martens, but that snow tracking also produced false-positive marten detections that could potentially substantially bias distribution estimates if not corrected for. Remote cameras detected marten individuals more readily than passive hair catches. Inability to photographically distinguish individual sex did not appear to induce negative bias in camera density estimates; instead, hair catches appeared to produce detection competition between individuals that may have been a source of negative bias. Our model reformulations broaden the range of circumstances in which analyses incorporating multiple sources of information can be robustly used, and our empirical results demonstrate that using multiple field-methods can enhance inferences regarding ecological parameters of interest and improve understanding of how reliably survey methods sample these parameters. [ABSTRACT FROM AUTHOR]

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 ± 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. [ABSTRACT FROM AUTHOR]

ABSTRACT Statistical population reconstruction using age-at-harvest and catch-effort data has recently emerged as a robust and versatile approach to estimating the demographic dynamics of harvested populations of wildlife. Although there are clear benefits to incorporating radio-telemetry data into reconstruction efforts, these data are costly and time-consuming to collect. Managers that consider collecting these data alongside existing efforts could benefit from a comprehensive examination of how such benefits are influenced by the amount of radio-telemetry data collected. Using a harvested population of American marten ( Martes americana) in northeastern Minnesota, USA as a case study, we investigated the performance of population reconstruction using information on natural, harvest, or combined mortality derived from radio-telemetry data collected over different numbers of years and with different numbers of animals collared each year. We simulated populations under a range of conditions and determined that incorporating radio-telemetry data on natural and harvest mortality significantly improved model precision, and that each additional animal collared per year yielded a 0.50 ± 0.14% (SE) improvement in precision, whereas every additional year of radio-telemetry data resulted in a 2.42 ± 0.70% improvement. Thus, including another year of radio-telemetry resulted in similar gains in precision as including approximately 5 additional animals collared per year. In our applied marten example, incorporating radio-telemetry data resulted in a significantly higher estimate of trapping vulnerability (0.20 vs. 0.058) and an overall smaller population size than reconstruction based solely on age-at-harvest and trapper effort data. These results illustrate the benefits of performing auxiliary studies, caution against relying on the results of population reconstruction based solely on age-at-harvest and hunter-effort data, and demonstrate that improvements from incorporating radio-telemetry data become evident even after as few as 2 years of data collection. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT We translocated and released a total of 90 (55 F and 35 M) wild American martens (Martes americana) from Minnesota to northern Wisconsin, USA, during 2008–2010. Our objective was to evaluate the short‐term results of this translocation project by comparing marten dispersal, time to residency, and survival by release method, sex, and age categories. On average, translocated martens took 18 days (range = 1–64 days) and traveled 4.6 km (range = 0.4–45.7 km) from release sites before establishing residency. Although survival probabilities for adults and males were 0.84 and 0.79 and juveniles and females were 0.66 and 0.71, respectively, they were not statistically different. Translocated adult and juvenile survival was similar to resident adult and juvenile survival reported in Wisconsin and elsewhere. Predation (primarily by other carnivores) was the main cause (85%) of observed mortality for translocated animals, but it did not appear to be a major limiting factor for adults or juveniles. Contrary to some studies, we found no significant difference between release methods for any analyzed parameter, but we observed increased injuries to slow‐released individuals. We concluded there was no benefit resulting from slow‐release or an acclimation period for translocation of American martens and that long‐term monitoring of the population is needed to evaluate species recovery in Wisconsin. © 2013 The Wildlife Society.