Development of 22 new microsatellite loci for fishers (Martes pennanti) with variability results from across their range

We developed 22 new microsatellite loci for the fisher (Martes pennanti), a North American mesocarnivore. The loci were developed with samples from the southern Sierra Nevada Mountains in California, and were screened with samples from this population and four other populations. We observed a range of six to 21 polymorphic loci per population, with the Sierra Nevada population exhibiting markedly lower levels of variation compared to the other four.     

Relationship between the annual rhythms in melatonin and immune system status in the tropical palm squirrel, Funambulus pennanti

Melatonin (MEL) regulation of seasonal variation in immunity has been studied extensively in temperate mammals. This report is the first on a tropical mammal, the Indian palm squirrel, F. pennanti. In response to the annual environmental cycle, we studied the rhythms of plasma MEL and the immune parameters of total blood leucocytes, absolute blood lymphocytes and blastogenic responses of blood, thymus and spleen lymphocytes. We found that in parallel with MEL all the immune parameters increased during the month of April onward, when natural day length, temperature, humidity and rainfall were increasing. Maximum values occurred during November (reproductively inactive phase) when the values of all the physical factors were comparatively low. Lowest values occurred during January-March (reproductively active phase) when the values of the physical factors were lowest. In order to establish a clear interrelationship between the pineal MEL and the immune system function, we manipulated these squirrels with exogenous MEL (25mg/100g B wt/day) at 1730 h during their pineal inactive phase (March) while another group was pinealectomized (Px) during November when their pineal was active. The MEL injection significantly increased all the immune parameters, while Px decreased them significantly. Hence, we suggest that MEL is immuno-enhancing for this tropical squirrel, and plays an important role in the maintenance of its immunity in accordance with the seasonal changes in environmental factors and gonadal status. (Chronobiology International, 18(1), 61-69, 2001)     

Conservation genetics of the fisher (Martes pennanti) based on mitochondrial DNA sequencing

Translocation of animals to re-establish extirpated populations or to maintain declining ones has often been carried out without genetic information on source or target populations, or adequate consideration of the potential effects of mixing genetic stocks. We consider the conservation status of the fisher (Martes pennanti) and evaluate the potential genetic consequences of past and future translocations on this medium-sized carnivore by examining population variation in mitochondrial control-region sequences. We sampled populations throughout the fisher's range in North America including five populations unaffected by translocations and two western populations that had received long-distance translocations. Twelve haplotypes showed little sequence divergence. Haplotype frequencies differed significantly among subspecies and between populations within subspecies. Analysis of molecular variance (amova) and neighbour-joining analyses of haplotype relationships revealed population subdivision similar to current subspecies designations, but which may reflect an isolation-by-distance pattern. Populations in Oregon and in Montana and Idaho received several translocations and each showed greater similarity to the populations where translocations originated than to adjacent populations. Additional sequences obtained from museum specimens collected prior to any translocations suggest historical gene flow among populations in British Columbia, Washington, Oregon, and California. Anthropogenic impacts in that region have greatly reduced and isolated extant populations in Oregon and California. Future translocations may be necessary to recover populations in Washington and portions of Oregon and California; our results indicate that British Columbia would be the most appropriate source population.     

Finding fishers: determining fisher occupancy in the Northern Rocky Mountains

Monitoring rare and elusive carnivores is inherently challenging because they often occur at low densities and require more resources to effectively assess status and trend. The fisher (Pekania pennanti) is an elusive mesocarnivore endemic to North America; in its western populations it is classified as a species of greatest conservation need. During winter of 2018–2019, we deployed remotely triggered cameras in randomly selected, spatially balanced 7.5-km × 7.5-km grid cells across a broad study area in western Montana, Idaho, and eastern Washington, USA. As part of this large-scale, multi-state monitoring effort, we conducted an occupancy assessment of the Northern Rocky Mountain fisher population at a range-wide scale. We used non-spatial occupancy models to determine the current extent of fisher occurrence in the Northern Rocky Mountains and to provide baseline occupancy estimates across a broad study area and a refined sampling frame for future monitoring. We used a spatial occupancy model to determine patterns in fisher occurrence across their Northern Rocky Mountain range while explicitly correcting for spatially induced overdispersion. Additionally, we assessed factors that influenced fisher occurrence through covariate occupancy modeling that considered predicted fisher habitat, site-level environmental characteristics, and the influence of available harvest records (incidental and regulated). We detected fishers in 32 out of 318 (10%) of our surveyed cells, and estimated that overall, 160 (14%; 95% CI = 115–218) of 1,143 grid cells were occupied by fishers. Fisher occupancy was positively associated with our stratum that contained cells with a greater proportion of predicted fisher habitat and with proximity to nearest 2000–2015 harvest location. Fisher occupancy was weakly and positively associated with increased canopy cover. Our spatial model identified 2 areas with higher predicted occupancy: a large area across the Idaho Nez Perce-Clearwater National Forest, and a smaller area in the Cabinet Mountain Range crossing the northern border of Idaho and Montana. We used spatial occupancy results from our original sampling frame to create a biologically derived refined sampling frame for future monitoring. Within the bounds of our refined sampling frame, we estimated that 155 (22%; 95% CI = 110–209) of 700 grid cells were occupied by fishers. By incorporating our increasing understanding of fisher habitat with contemporary analytical techniques, we defined current range-wide occupancy of the Northern Rocky Mountain fisher population, identified core areas of fisher occurrence for future conservation efforts, and used our model results to create a refined sampling frame for future fisher monitoring in the Northern Rocky Mountains.     

A framework for inference about carnivore density from unstructured spatial sampling of scat using detector dogs

Wildlife management often hinges upon an accurate assessment of population density. Although undeniably useful, many of the traditional approaches to density estimation such as visual counts, livetrapping, or mark–recapture suffer from a suite of methodological and analytical weaknesses. Rare, secretive, or highly mobile species exacerbate these problems through the reality of small sample sizes and movement on and off study sites. In response to these difficulties, there is growing interest in the use of non-invasive survey techniques, which provide the opportunity to collect larger samples with minimal increases in effort, as well as the application of analytical frameworks that are not reliant on large sample size arguments. One promising survey technique, the use of scat detecting dogs, offers a greatly enhanced probability of detection while at the same time generating new difficulties with respect to non-standard survey routes, variable search intensity, and the lack of a fixed survey point for characterizing non-detection. In order to account for these issues, we modified an existing spatially explicit, capture–recapture model for camera trap data to account for variable search intensity and the lack of fixed, georeferenced trap locations. We applied this modified model to a fisher (Martes pennanti) dataset from the Sierra National Forest, California, and compared the results (12.3 fishers/100 km²) to more traditional density estimates. We then evaluated model performance using simulations at 3 levels of population density. Simulation results indicated that estimates based on the posterior mode were relatively unbiased. We believe that this approach provides a flexible analytical framework for reconciling the inconsistencies between detector dog survey data and density estimation procedures. © 2011 The Wildlife Society.     

Genetic variation and structure of fisher (Martes pennanti) populations across North America

Fishers are mid-sized forest carnivores indigenous to North America that experienced sharp population declines from the early 1800s through to the mid-1900s. To evaluate levels of genetic variation within and subdivision among northern fisher populations 459 individuals were genotyped using 13 microsatellite loci. Genetic diversity was found to be slightly lower in re-introduced populations than in adjacent indigenous populations. Furthermore, fisher populations revealed much more genetic structuring than two closely related mustelids. Further investigation is needed to determine if fishers are more philopatric than martens and wolverines or if barriers to dispersal explain the levels of structure identified in this study.     

Fisher Survival in Eastern Ontario

Abstract: Fishers (Martes pennanti) have recolonized eastern Ontario, Canada, but little is known about the survival of this harvested population. We estimated fisher survival and cause-specific mortality in Leeds and Grenville County, Ontario, from 2003–2005. The overall 2-year survival rate (95% CI) was 0.35 (0.21-0.56, n = 59). We attributed observed mortality rates mainly to natural causes (28.6%) and nuisance trapping (21.4%). Given reported recruitment rates, our estimated fisher mortality has likely led to population declines in the study area, especially during 2003. Thus, we do not recommend an increase in fisher harvest quotas in the study area at this time.     

Using Patterns in Track-Plate Footprints to Identify Individual Fishers

Abstract: If individuals can be identified from patterns in their footprints, noninvasive survey methods can be used to estimate abundance. Track plates capture fine detail in the footprints of fishers (Martes pennanti), recording rows of dots corresponding to tiny papillae on the animal's metacarpal pad. We show that the pattern of these dots can be used to identify individual fishers, similar to human fingerprints. A probabilistic model of uniqueness based on variation in spacing between 1,400 pairs of dots that we measured in prints of 14 different fisher feet suggests the probability of encountering a similar pattern in the print of a different foot by chance alone is ≤ 0.35ⁿ, where n = the number of dot pairs examined. This predicts a 0.00003 probability that a match made using 10 pairs of dots is false. Dot spacing from footprints made by the same foot was remarkably consistent (sN = 0.02 mm, n = 24 dot pairs). Combined, these results suggest dot patterns in fisher footprints were unique to individuals and were consistently reproduced on track plates. Empirical tests of matching accuracy were best with good-quality prints, highlighting the need for experience judging when prints are usable. We applied print matching to fisher detections collected on track plates deployed at 500-m intervals along 10 3.5-km transects in the Adirondack region of New York, USA. Of 62 fisher detections, 85% had ≥ 1 footprint of suitable quality to compare with other high-quality prints. We found that most detections from a transect were from the same individual fisher suggesting nonindependence of detections. Thus, data from traditional track-plate deployments over small time periods cannot be used as a measure of abundance, but new study designs using print matching could obtain robust noninvasive, mark—recapture density estimates.     

PHOTOPERIODIC REGULATION OF MT1 AND MT2 MELATONIN RECEPTOR EXPRESSION IN SPLEEN AND THYMUS OF A TROPICAL RODENT FUNAMBULUS PENNANTI DURING REPRODUCTIVELY ACTIVE AND INACTIVE PHASES

Photoperiodic regulation of melatonin receptor types on target tissues, such as lymphatic organs, has never been explored for any seasonal breeder. In the present study, we accessed the high affinity membrane melatonin receptors MT1 and MT2 expression dynamics in lymphoid organs (i.e., spleen and thymus) of a seasonally breeding rodent Funambulus pennanti during two major reproductive phases (i.e., active and inactive), when the internal hormonal (melatonin and gonadal steroid) as well as the ecological conditions were entirely different. Photoperiod regulates circulatory melatonin level; hence, we noted the effect of different photoperiodic regimes (long; 16L:8D and short; 10L:14D photoperiod) equivalent to summer and winter daylength on membrane melatonin receptor MT1 and MT2 expression in spleen and thymus. We have correlated the melatonin receptor expression with two major hormones varying seasonally (i.e., melatonin and testosterone) also being responsible for modulation of immunity of a seasonal breeder. Differential immunoreactivity of MT1 and MT2 receptor in spleen and thymus of F. pennanti suggests an involvement of both the receptor types in signal transduction of photoperiod for seasonal immunomodulation, because in the tropical zone, a slight difference (1:45–2?h) in daylength may change reproductive physiology and immunity of animals for adaptation. Our above suggestion receives strong support from the experiment of photoperiodic exposure on MT1 and MT2 expression at the translational level, where long daylength decreased the circulatory melatonin level and melatonin receptor expression in both lymphatic tissues. On the other hand, under short daylength, expression of MT1 and MT2 receptor increased in both spleen and thymus along with concomitant increase in circulatory melatonin level. Differential hormonal level of melatonin and gonadal hormones during reproductively active and inactive phase and its direct relation with melatonin receptor expression dynamics in lymphoid organs could be responsible for seasonal adjustment of immunity and reproduction. (Author correspondence: chaldar2001@yahoo.com)     

Post-release survival of translocated fishers: implications for translocation success

As a vital tool for the conservation of species at risk, translocations are also opportunities to identify factors that influence translocation success. We evaluated factors associated with post-release survival of 90 radio-tracked fishers (Pekania pennanti) translocated from central British Columbia, Canada, to the Olympic Peninsula of Washington, USA, from 2008 to 2011. We hypothesized that the survival of translocated fishers would be affected by the same factors that influence the survival of resident, native fishers (i.e., sex, age, season, body condition), and additional factors that were associated with the translocation process (e.g., duration of captivity, release date, yr of release). Fisher survival was most strongly influenced by translocation year (i.e., release-yr cohort), season, sex, and age class of fisher; whereas duration of captivity, standardized body mass, release date, and number of intact canines did not influence survival. Survival was lowest for fishers released in cohort 2 in 2009 and during the breeding season (Mar–Jun), and was greatest for juveniles and males. When combined across release-year cohorts, year 1 survival rates were greatest for juvenile males followed by juvenile females, adult females, and adult males. Sex and age-related differences in survival of translocated fishers were counter to those commonly reported for established fisher populations, where adult females often have the highest survival rates and juveniles the lowest. Predation (40%) and vehicle strikes (20%) were the most common causes of known mortality among the 24 recovered fishers for which cause of death was determined. We speculate that females face higher risks of mortality in translocated populations because their small size makes them more vulnerable to predation and because adult females in resident populations are less likely than males and juveniles to disperse. Our findings support designing translocations that favor releasing a preponderance of female fishers in recognition of their lower survival rates and to ensure adequate breeders are established in the population, and juvenile and young adult fishers to enhance survival of both sexes. Releases conducted over multiple years will minimize the impact of stochastic annual events that may adversely affect survival in any given year. Persistence, widespread distribution, and documented reproduction of fishers within our study area for ≥6 years following the last releases indicate that survival parameters we measured contributed toward successful population establishment over the short term.     

Using a genetic network to parameterize a landscape resistance surface for fishers, Martes pennanti

Knowledge of dispersal-related gene flow is important for addressing many basic and applied questions in ecology and evolution. We used landscape genetics to understand the recovery of a recently expanded population of fishers (Martes pennanti) in Ontario, Canada. An important focus of landscape genetics is modelling the effects of landscape features on gene flow. Most often resistance surfaces in landscape genetic studies are built a priori based upon nongenetic field data or expert opinion. The resistance surface that best fits genetic data is then selected and interpreted. Given inherent biases in using expert opinion or movement data to model gene flow, we sought an alternative approach. We used estimates of conditional genetic distance derived from a network of genetic connectivity to parameterize landscape resistance and build a final resistance surface based upon information-theoretic model selection and multi-model averaging. We sampled 657 fishers from 31 landscapes, genotyped them at 16 microsatellite loci, and modelled the effects of snow depth, road density, river density, and coniferous forest on gene flow. Our final model suggested that road density, river density, and snow depth impeded gene flow during the fisher population expansion demonstrating that both human impacts and seasonal habitat variation affect gene flow for fishers. Our approach to building landscape genetic resistance surfaces mitigates many of the problems and caveats associated with using either nongenetic field data or expert opinion to derive resistance surfaces.     

Evaluating management risks using landscape trajectory analysis: A case study of California fisher

Ecosystem management requires an understanding of how landscapes vary in space and time, how this variation can be affected by management decisions or stochastic events, and the potential consequences for species. Landscape trajectory analysis, coupled with a basic knowledge of species habitat selection, offers a straightforward approach to ecological risk analysis and can be used to project the effects of management decisions on species of concern. The fisher (Martes pennanti) occurs primarily in late-successional forests which, in the Sierra Nevada mountains, are susceptible to high-intensity wildfire. Understanding the effects of fuels treatments and fire on the distribution of fisher habitat is a critical conservation concern. We assumed that the more a treated landscape resembled occupied female fisher home ranges, the more likely it was to be occupied by a female and therefore the lower the risk to the population. Thus, we characterized important vegetation attributes within the home ranges of 16 female fishers and used the distribution of these attributes as a baseline against which the effects of forest management options could be compared. We used principal components analysis to identify the major axes defining occupied female fisher home ranges and these, in addition to select univariate metrics, became our reference for evaluating the effects of landscape change. We demonstrated the approach at two management units on the Sierra National Forest by simulating the effects of both no action and forest thinning, with and without an unplanned fire, on vegetation characteristics over a 45-yr period. Under the no action scenario, landscapes remained similar to reference conditions for approximately 30-yr until forest succession resulted in a loss of landscape heterogeneity. Comparatively, fuel treatment resulted in the reduction of certain forest elements below those found in female fisher home ranges yet little overall change in habitat suitability. Adding a wildfire to both scenarios resulted in divergence from reference conditions, though in the no action scenario the divergence was 4× greater and the landscape did not recover within the 45-yr timeframe. These examples demonstrate that combining the results of forest growth and disturbance modeling with habitat selection data may be used to quantify the potential effects of vegetation management activities on wildlife habitat. © 2011 The Wildlife Society.     

The Debate About Bait: A Red Herring in Wildlife Research

The use of bait (or attractants) to lure animals to a sampling site is common in wildlife research and important for optimizing species detection rates. The effect of bait on animal movement and space-use, however, is contested, fueled by concerns bait may affect animal movement and increase residency time. If founded, bait may bias parameter estimates from density, species distribution, resource selection, or behavioral models, produce spurious ecological inferences, and skew resulting management recommendations. To test whether animal movement varies with proximity to bait, we used high-resolution global positioning system telemetry data of 10 fishers (Pekania pennanti), temporally paired with 64 baited wildlife camera traps, to quantify the effect of bait on individual and population movement metrics. Although bait appeared to have a significant correlative effect on 1-hour movement segments, landscape characteristics had an effect 1.7 times greater, where the proportion of mixed forest and cultivation explained the majority of variability in animal movements. We contend that maximizing probability of detection and controlling or modeling local-scale landscape variability that could affect the probability of detection is a more important consideration in wildlife research than the effect of bait, which is eclipsed by differences incurred by natural habitat heterogeneity. Failing to maximize the probability of detection may obscure the modest bias potentially presented by the use of bait, or attractants, on ecological inference. © 2019 The Wildlife Society     

Home Range and Population Density of Fishers in Eastern Ontario

Abstract: Fishers (Martes pennanti) were almost extirpated in Ontario, Canada, south of the French and Mattawa rivers by the 1940s but have recolonized much of their former range over the past several decades. We assessed the effect of the current harvest quota on a fisher population in eastern Ontario by estimating home range size and population density from a sample of radiocollared animals. Mean (± SD) adult home ranges (based on annual 95% min. convex polygons) were consistently smaller than those reported in the literature (M: 11 ± 4.4 km²; F: 2.1 ± 0.8 km²), with up to 71% overlap of adjacent intrasexual home ranges. This yielded an estimated adult fisher population density of 32.7/100 km² of suitable habitat, as defined by the habitat composition within observed home ranges. We further estimated that between 2003 and 2005, trappers harvested 17.8-42.3% of the pretrapping population. These results suggest that although current fisher population density is high in our study area compared to reported densities in other areas, harvest rate is also high and an increase in quota is unwarranted.     

Occupancy Patterns in a Reintroduced Fisher Population during Reestablishment

Monitoring population performance in the years following species reintroductions is key to assessing population restoration success and evaluating assumptions made in planning species restoration programs. From 2008–2010 we translocated 90 fishers (Pekania pennanti) from British Columbia, Canada, to Washington's Olympic Peninsula, USA, providing the opportunity to evaluate modeling assumptions used to identify the most suitable reintroduction areas in Washington and enhance understanding of fisher habitat associations in the late-successional forest ecosystems in the coastal Pacific Northwest. From 2013–2016, we deployed 788 motion-sensing cameras and hair (DNA)-snaring devices distributed among 263 24-km² primary sampling units across the Olympic Peninsula. Our objectives were to determine whether occupancy patterns of the reestablishing population supported assumptions of the initial habitat assessment models, whether the population had expanded or shifted in distribution since the initial reintroductions, compare physical habitat attributes among land-management designations, and determine whether the founding fishers had successfully reproduced. We predicted that site occupancy by fishers would be associated with landscapes characterized by high proportional coverage of dense forest canopies and medium-sized and large trees, a diversity of stand structural classes, and area near the administrative boundary separating wilderness from more intensively managed forest lands. We detected fishers across designated wilderness, federal lands outside of wilderness, and other land designations in proportion to land availability on the Peninsula. We found negligible support for predictions that occupancy by fishers was associated with percent forest cover, tree-size class, or structural class diversity. Rather, occupancy was strongly associated with lands near the wilderness boundary on both sides. We speculate that the boundary between wilderness and more intensively managed forest lands provided fishers with the most suitable prey in proximity to contiguous expanses of low- to mid-elevation late-successional forests that provided optimal resting, denning, and security values. Occupancy patterns shifted toward the west and south along a precipitation gradient during the study, indicating that population distribution had not yet stabilized 5–8 years following translocation. Genetic results indicated that ≥2 generations of fishers have been produced on the Peninsula. Annual occupancy rates across the Peninsula (0.08–0.24) were lower than in other previously studied and established fisher populations, indicating that not all habitat was fully occupied or that initial estimates of the extent of habitat was overestimated. The strong selection fishers exhibited for wilderness edge and weak selection against extensive forested wilderness areas suggested that habitat managers should strive for maintaining a suitable interspersion of required forest structures and biotic habitat components, such as prey resource availability. © 2019 The Wildlife Society.     

Factors Affecting Landscape Occupancy by Fishers in North-Central British Columbia

ABSTRACT To better understand distribution and density of fishers (Martes pennanti) in industrial forests of north-central British Columbia, Canada, we examined factors affecting the probability of a potential home range being occupied by 10 radiotagged resident fishers in the Sub-Boreal Spruce biogeoclimatic zone between 1996 and 2000. Percentage of a home range in wetlands and recently logged (within past 12 yr) best predicted likelihood of occupancy by each fisher. Probability of a home range area being occupied by a resident fisher decreased with increasing amounts of wetlands and recent logging present in the area. We estimated that a 5% increase in wetlands or recent logging decreased the relative probability of occupancy of a potential home range by 50%. The accelerated rate of timber harvest in forests affected by mountain pine beetle (Dendroctonus ponderosae) infestations may have substantial implications for the ability of the landscape of central British Columbia to support sustainable populations of fishers.