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Factors Influencing the Post-Release Movements of Translocated Fishers: Implications for Translocation Success. JOURNAL OF FISH AND WILDLIFE MANAGEMENT 2021. [DOI: 10.3996/jfwm-21-023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Long distance, post-release movements of translocated wildlife can be a key factor limiting translocation success. Yet, for many species, we have little or no understanding of factors that influence post-release movements. Translocations have been important for recovering fisher Pekania pennanti populations across the southern portion of their North American range. However, little is known about the post-release movements of translocated fishers and how these movements may be influenced by demographic or translocation-process factors. To restore fishers in Washington State, we moved 90 fishers from central British Columbia and released them at nine sites in the Olympic Fisher Recovery Area on the Olympic Peninsula of Washington from 2008 to 2010. We evaluated post-release movements of 48 fishers to determine both the distance and duration of movements prior to home range establishment. Fishers moved extensively following their release. Multi-model selection indicated a high level of support for the hypothesis that post-release movements differed by fisher sex and age; whereas, year of release had no apparent effect on movements, and release date had only a marginal influence on male movements. Mean distance (± 95% CI) from a release site to a home range was greater for adult males (62.0 ± 19.6 km) than for juvenile males (31.4 ± 16.0 km), adult females (30.9 ± 21.1 km), and juvenile females (29.0 ± 13.5 km). Mean number of days from release until home range establishment was similar for the sexes, however the variance in movement duration was greater for females. Twenty-six of 27 females established home ranges over an 11-month period (December-October), while 19 of 21 males did so within a 4-month period (April-July). Mean home range sizes differed between males (128.3 ± 21.1 km2) and females (63.5 ± 9.0 km2) and were among the largest reported for the species. A greater proportion of females (18 of 27; 67%) than males (8 of 21; 38%) established home ranges within or partially within the recovery area. Six females left a previously established home range during the breeding season, presumably to find breeding males. Given the large distances that fishers can move following release, translocation success could be furthered by releasing individuals at fewer sites in the interior of large reintroduction areas to facilitate greater exposure to a recovery area and greater opportunity to interact with conspecifics and potential mates.
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Jensen PG, Humphries MM. Abiotic conditions mediate intraguild interactions between mammalian carnivores. J Anim Ecol 2019; 88:1305-1318. [PMID: 31236935 DOI: 10.1111/1365-2656.13024] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/27/2019] [Indexed: 11/29/2022]
Abstract
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.
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Affiliation(s)
- Paul G Jensen
- Department of Natural Resource Sciences, McGill University, Ste.-Anne-de-Bellevue, Québec, Canada.,Division of Fish and Wildlife, New York State Department of Environmental Conservation, Ray Brook, New York
| | - Murray M Humphries
- Department of Natural Resource Sciences, McGill University, Ste.-Anne-de-Bellevue, Québec, Canada
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3
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Greenhorn JE, Bowman J, Wilson PJ. Genetic monitoring suggests increasing structure following recolonization by fishers. J Wildl Manage 2018. [DOI: 10.1002/jwmg.21495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Janet E. Greenhorn
- Environmental and Life Sciences Graduate Program; Trent University; 2140 East Bank Drive Peterborough ON K9L 0G2 Canada
| | - Jeff Bowman
- Wildlife Research and Monitoring Section; Ontario Ministry of Natural Resources and Forestry; 2140 East Bank Drive Peterborough ON K9L 0G2 Canada
| | - Paul J. Wilson
- Department of Biology; Trent University; 2140 East Bank Drive Peterborough ON K9L 0G2 Canada
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Green DS, Matthews SM, Swiers RC, Callas RL, Scott Yaeger J, Farber SL, Schwartz MK, Powell RA. Dynamic occupancy modelling reveals a hierarchy of competition among fishers, grey foxes and ringtails. J Anim Ecol 2018; 87:813-824. [DOI: 10.1111/1365-2656.12791] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 11/26/2017] [Indexed: 11/29/2022]
Affiliation(s)
- David S. Green
- Institute for Natural Resources Oregon State University Corvallis OR USA
| | - Sean M. Matthews
- Institute for Natural Resources Oregon State University Corvallis OR USA
| | - Robert C. Swiers
- Department of Applied Ecology North Carolina State University Raleigh NC USA
| | | | | | | | | | - Roger A. Powell
- Department of Applied Ecology North Carolina State University Raleigh NC USA
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Bertrand P, Bowman J, Dyer RJ, Manseau M, Wilson PJ. Sex-specific graphs: Relating group-specific topology to demographic and landscape data. Mol Ecol 2017; 26:3898-3912. [PMID: 28488269 DOI: 10.1111/mec.14174] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 04/24/2017] [Accepted: 04/25/2017] [Indexed: 02/01/2023]
Abstract
Sex-specific genetic structure is a commonly observed pattern among vertebrate species. Facing differential selective pressures, individuals may adopt sex-specific life history traits that ultimately shape genetic variation among populations. Although differential dispersal dynamics are commonly detected in the literature, few studies have used genetic structure to investigate sex-specific functional connectivity. The recent use of graph theoretic approaches in landscape genetics has demonstrated network capacities to describe complex system behaviours where network topology represents genetic interaction among subunits. Here, we partition the overall genetic structure into sex-specific graphs, revealing different male and female dispersal dynamics of a fisher (Pekania [Martes] pennanti) metapopulation in southern Ontario. Our analyses based on network topologies supported the hypothesis of male-biased dispersal. Furthermore, we demonstrated that the effect of the landscape, identified at the population level, could be partitioned among sex-specific strata. We found that female connectivity was negatively correlated with snow depth, whereas connectivity among males was not. Our findings underscore the potential of conducting sex-specific analysis by identifying landscape elements or configuration that differentially promotes or impedes functional connectivity between sexes, revealing processes that may otherwise remain cryptic. We propose that the sex-specific graph approach would be applicable to other vagile species where differential sex-specific processes are expected to occur.
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Affiliation(s)
- Philip Bertrand
- Département de Biologie, Chimie & Géographie, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Jeff Bowman
- Wildlife Research & Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Trent University, Peterborough, ON, Canada
| | - Rodney J Dyer
- Center for Environmental Studies, Virginia Commonwealth University, Richmond, VA, USA
| | - Micheline Manseau
- Office of the Chief Ecosystem Scientist, Gatineau, QC, Canada.,Natural Resources Institute, University of Manitoba, Winnipeg, MB, Canada
| | - Paul J Wilson
- Biology Department, Trent University, Peterborough, ON, Canada
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6
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Sweitzer RA, Thompson CM, Green RE, Barrett RH, Purcell KL. Survival of fishers in the southern Sierra Nevada region of California. J Mammal 2015. [DOI: 10.1093/jmammal/gyv177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Fishers in the western United States were recently proposed for listing under the U.S. Endangered Species Act because of concerns for loss of suitable habitat and evidence of a diversity of mortality risks that reduce survival. One of 2 remnant populations of fishers in California is in the southern Sierra Nevada region, where we studied them at 2 research sites in the Sierra National Forest. Our objectives were to evaluate whether survival was lower for male fishers and dispersal-aged individuals or if survival varied seasonally. We captured and monitored 232 radiocollared fishers from March 2007 to March 2014 and used model analyses to identify important predictors of survival. Fifty-two percent ( n = 120) of the radiocollared fishers died, and survival varied by sex and season, but not by age or between study sites. There was no evidence that dispersal-aged fishers experienced lower survival than older fishers. Annual survival trended lower for male (0.62 [95% CI 0.54–0.70]) compared to female fishers (0.72 [95% CI 0.67–0.78]), was lowest in the spring to mid-summer season (0.83 [95% CI 0.78–0.87]), and highest in late fall and winter (0.92 [95% CI 0.89–0.94]). Lower survival among male fishers appeared linked to males moving over large areas to locate mates, while lower survival for females was potentially related to high energetic cost of reproduction. It was possible but unknown if lower survival among all fishers in spring was linked to secondary exposure to toxicants dispersed around illicit marijuana grow sites. Six-month survival of juvenile fishers was 0.85 for females and 0.79 for males, but lower at 0.62 for females and 0.57 for males when adjusted for deaths before late September. Annual survival among adult female fishers was 20% lower than 0.90, a value that prior modeling suggested was required for population expansion in the overall southern Sierra Nevada. Survival data from our study imply a greater challenge for maintaining self-sustaining fisher populations in the southern Sierra Nevada region, and resource managers are working to mitigate several of the human-associated factors that limit population growth.
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Larroque J, Ruette S, Vandel JM, Devillard S. “False heat,” big testes, and the onset of natal dispersal in European pine Martens (Martes martes). EUR J WILDLIFE RES 2014. [DOI: 10.1007/s10344-014-0889-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Lubelczyk C, Lacombe EH, Elias SP, Beati L, Rand PW, Smith RP. Parasitism of mustelids by ixodid ticks (Acari: Ixodidae), Maine and New Hampshire, U.S.A. Ticks Tick Borne Dis 2014; 5:432-5. [PMID: 24690190 DOI: 10.1016/j.ttbdis.2014.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/20/2013] [Accepted: 02/07/2014] [Indexed: 11/25/2022]
Abstract
Ticks collected from mustelids from four counties in Maine and one in New Hampshire were identified after harvest. Of the 18 fishers Martes pennanti Erxleben, two mink Neovison vison Schreber, and one long-tailed weasel Mustela frenata Lichtenstein, 589 ticks were collected and identified. They were identified as, in order of abundance, Ixodes gregsoni Lindquist, Wu, and Redner (158 larvae, 189 nymphs, four adults), Ixodes cookei Packard (99 larvae, 77 nymphs, six adults), Ixodes scapularis Say (53 adults), Dermacentor variabilis Say (two nymphs), and Ixodes angustus Neumann (one nymph). Seasonally, all but the D. variabilis were collected in winter. This study reports the first record of adult I. scapularis from a M. pennanti in the northeastern United States.
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Affiliation(s)
- Charles Lubelczyk
- Maine Medical Center Research Institute, Vector-borne Disease Laboratory, 75 John Roberts Road Suite 9B, South Portland, ME 04106, USA.
| | - Eleanor H Lacombe
- Maine Medical Center Research Institute, Vector-borne Disease Laboratory, 75 John Roberts Road Suite 9B, South Portland, ME 04106, USA
| | - Susan P Elias
- Maine Medical Center Research Institute, Vector-borne Disease Laboratory, 75 John Roberts Road Suite 9B, South Portland, ME 04106, USA
| | - Lorenza Beati
- United States National Tick Collection, Georgia Southern University, P.O. Box 8056, Statesboro, GA 30460, USA
| | - Peter W Rand
- Maine Medical Center Research Institute, Vector-borne Disease Laboratory, 75 John Roberts Road Suite 9B, South Portland, ME 04106, USA
| | - Robert P Smith
- Maine Medical Center Research Institute, Vector-borne Disease Laboratory, 75 John Roberts Road Suite 9B, South Portland, ME 04106, USA
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Weir RD, Lofroth EC, Phinney M, Harris LR. Spatial and Genetic Relationships of Fishers in Boreal Mixed-Wood Forests of Northeastern British Columbia. NORTHWEST SCIENCE 2013. [DOI: 10.3955/046.087.0204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Matthews SM, Higley JM, Rennie KM, Green RE, Goddard CA, Wengert GM, Gabriel MW, Fuller TK. Reproduction, recruitment, and dispersal of fishers (Martes pennanti) in a managed Douglas-fir forest in California. J Mammal 2013. [DOI: 10.1644/11-mamm-a-386.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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11
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Leoniak G, Barnum S, Atwood JL, Rinehart K, Elbroch M. Testing GIS-Generated Least-Cost Path Predictions forMartes pennanti(Fisher) and its Application for Identifying Mammalian Road-crossings in Northern New Hampshire. Northeast Nat (Steuben) 2012. [DOI: 10.1656/045.019.0201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Jordan MJ, Barrett RH, Purcell KL. Camera trapping estimates of density and survival of fishers Martes pennanti. WILDLIFE BIOLOGY 2011. [DOI: 10.2981/09-091] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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13
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GARROWAY COLINJ, BOWMAN JEFF, WILSON PAULJ. Using a genetic network to parameterize a landscape resistance surface for fishers, Martes pennanti. Mol Ecol 2011; 20:3978-88. [DOI: 10.1111/j.1365-294x.2011.05243.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Garroway CJ, Bowman J, Carr D, Wilson PJ. Applications of graph theory to landscape genetics. Evol Appl 2008; 1:620-30. [PMID: 25567802 PMCID: PMC3352384 DOI: 10.1111/j.1752-4571.2008.00047.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 08/24/2008] [Indexed: 12/03/2022] Open
Abstract
We investigated the relationships among landscape quality, gene flow, and population genetic structure of fishers (Martes pennanti) in ON, Canada. We used graph theory as an analytical framework considering each landscape as a network node. The 34 nodes were connected by 93 edges. Network structure was characterized by a higher level of clustering than expected by chance, a short mean path length connecting all pairs of nodes, and a resiliency to the loss of highly connected nodes. This suggests that alleles can be efficiently spread through the system and that extirpations and conservative harvest are not likely to affect their spread. Two measures of node centrality were negatively related to both the proportion of immigrants in a node and node snow depth. This suggests that central nodes are producers of emigrants, contain high-quality habitat (i.e., deep snow can make locomotion energetically costly) and that fishers were migrating from high to low quality habitat. A method of community detection on networks delineated five genetic clusters of nodes suggesting cryptic population structure. Our analyses showed that network models can provide system-level insight into the process of gene flow with implications for understanding how landscape alterations might affect population fitness and evolutionary potential.
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Affiliation(s)
- Colin J Garroway
- Environmental and Life Sciences Graduate Program, Trent University Peterborough, ON, Canada
| | - Jeff Bowman
- Wildlife Research and Development Section, Ontario Ministry of Natural Resources Peterborough, ON, Canada
| | - Denis Carr
- Environmental and Life Sciences Graduate Program, Trent University Peterborough, ON, Canada
| | - Paul J Wilson
- Biology Department, Trent University Peterborough, ON, Canada
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Davis FW, Seo C, Zielinski WJ. Regional variation in home-range-scale habitat models for fisher (Martes pennanti) in California. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2007; 17:2195-2213. [PMID: 18213963 DOI: 10.1890/06-1484.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We analyzed recent survey data and mapped environmental variables integrated over a home range scale of 10 km2 to model the distribution of fisher (Martes pennanti) habitat in California, USA. Our goal was to identify habitat factors associated with the current distribution of fishers in California, and to test whether those factors differ for widely disjunct northern and southern populations. Our analyses were designed to probe whether poor habitat quality can explain the current absence of fishers in the historically occupied central and northern Sierra Nevada region that separates these two populations. Fishers were detected at 64/433 (14.8%) sample units, including 35/111 (32%) of sample units in the Klamath/Shasta region and 28/88 (32%) of sample units in the southern Sierra Nevada. Generalized additive models (GAM) that included mean annual precipitation, topographic relief, forest structure, and a spatial autocovariate term best predicted fisher detections over the species' recent historical range in California. Models derived using forest structure data from ground plots were comparable to models derived from Landsat Thematic Mapper imagery. Models for the disjunct Klamath/Cascades and southern Sierra Nevada populations selected different environmental factors and showed low agreement in the spatial pattern of model predictions. Including a spatial autocovariate term significantly improved model fits for all models except the southern Sierra Nevada. We cannot rule out dispersal or habitat in explaining the absence of fishers in the northern and central Sierra Nevada, but mapped habitat quality is low over much of the region. Landscapes with good fisher habitat may exist in rugged forested canyons of the currently unoccupied northern Sierra Nevada, but these areas are fragmented and at least 60 km from the nearest recent fisher detections.
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Affiliation(s)
- Frank W Davis
- Donald Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106-5131, USA.
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16
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Blanco JC, Cortés Y. Dispersal patterns, social structure and mortality of wolves living in agricultural habitats in Spain. J Zool (1987) 2007. [DOI: 10.1111/j.1469-7998.2007.00305.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Carr D, Bowman J, J. Wilson P. Density-dependent dispersal suggests a genetic measure of habitat suitability. OIKOS 2007. [DOI: 10.1111/j.0030-1299.2007.15568.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Proulx G. Using forest inventory data to predict winter habitat use by fisherMartes pennanti in British Columbia, Canada. ACTA ACUST UNITED AC 2006. [DOI: 10.1007/bf03192679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kyle CJ, Robitaille JF, Strobeck C. Genetic variation and structure of fisher (Martes pennanti) populations across North America. Mol Ecol 2001; 10:2341-7. [PMID: 11555275 DOI: 10.1046/j.1365-294x.2001.01351.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
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.
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Affiliation(s)
- C J Kyle
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada.
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Fuller TK, York EC, Powell SM, Decker TA, DeGraaf RM. An evaluation of territory mapping to estimate fisher density. CAN J ZOOL 2001. [DOI: 10.1139/z01-129] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated winter-territory mapping as a method for estimating fisher (Martes pennanti) density in a 210-km2 survey area in north-central Massachusetts in 1994 and 1995 by comparing estimates with simultaneous camera markresight estimates. Assuming intrasexual territoriality and accounting for all occupied habitat, territories of resident radio-marked fishers were mapped (mean = 54% of all territories in the study area), and those of unmarked resident fishers were identified from tracks and photographs. The total number indicated a population of 40 (19/100 km2) and 49 (23/100 km2) residents for 1994 and 1995, respectively. Results from replicated automatic-camera capturemarkresight surveys suggested slightly higher total numbers and densities of fishers in 1994 (44.5; 21/100 km2) and 1995 (52.9; 25/100 km2), but these estimates likely also included nonresident juveniles. Territory mapping and automatic-camera markresight methods resulted in very similar population estimates, but both require large numbers of radio-marked fishers to effectively detect small population changes (e.g., such as the 20% observed in this study). Individually marking animals would enhance markrecapture estimates.
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