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PLoS One. 2015 Nov 4;10(11):e0140640. doi: 10.1371/journal.pone.0140640. eCollection 2015.

Patterns of Natural and Human-Caused Mortality Factors of a Rare Forest Carnivore, the Fisher (Pekania pennanti) in California.

Author information

1
Integral Ecology Research Center, Blue Lake, California, United States of America.
2
Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, University of California Davis, Davis, California, United States of America.
3
California Animal Health and Food Safety Laboratory System, University of California Davis, California, United States of America.
4
University of California Davis, School Veterinary Medicine, Davis, CA, United States of America.
5
Wildlife Department, Hoopa Tribal Forestry, Hoopa, California, United States of America.
6
Pacific Southwest Research Station-Sierra Nevada Research Center, United States Forest Service, Fresno, California, United States of America.
7
Wildlife Conservation Society, Hoopa, California, United States of America.
8
Sierra Nevada Adaptive Management Project, University of California, Berkeley, California, United States of America.
9
Department of Pathology, Microbiology and Immunology, University of California Davis, Davis, California, United States of America.
10
Department of Wildlife, Humboldt State University, Arcata, California, United States of America.
11
Wildlife Investigations Laboratory, California Department of Fish and Wildlife, Rancho Cordova, California, United States of America.
12
Department of Population Health and Reproduction, University of California Davis, Davis, California, United States of America.

Abstract

Wildlife populations of conservation concern are limited in distribution, population size and persistence by various factors, including mortality. The fisher (Pekania pennanti), a North American mid-sized carnivore whose range in the western Pacific United States has retracted considerably in the past century, was proposed for threatened status protection in late 2014 under the United States Endangered Species Act by the United States Fish and Wildlife Service in its West Coast Distinct Population Segment. We investigated mortality in 167 fishers from two genetically and geographically distinct sub-populations in California within this West Coast Distinct Population Segment using a combination of gross necropsy, histology, toxicology and molecular methods. Overall, predation (70%), natural disease (16%), toxicant poisoning (10%) and, less commonly, vehicular strike (2%) and other anthropogenic causes (2%) were causes of mortality observed. We documented both an increase in mortality to (57% increase) and exposure (6%) from pesticides in fishers in just the past three years, highlighting further that toxicants from marijuana cultivation still pose a threat. Additionally, exposure to multiple rodenticides significantly increased the likelihood of mortality from rodenticide poisoning. Poisoning was significantly more common in male than female fishers and was 7 times more likely than disease to kill males. Based on necropsy findings, suspected causes of mortality based on field evidence alone tended to underestimate the frequency of disease-related mortalities. This study is the first comprehensive investigation of mortality causes of fishers and provides essential information to assist in the conservation of this species.

PMID:
26536481
PMCID:
PMC4633177
DOI:
10.1371/journal.pone.0140640
[Indexed for MEDLINE]
Free PMC Article

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