Hoopa, CA, United States
Hoopa, CA, United States

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Stephenson N.,University of California at Davis | Blaney A.,University of California at Davis | Clifford D.,University of California at Davis | Gabriel M.,University of California at Davis | And 6 more authors.
Ticks and Tick-borne Diseases | Year: 2017

Far northern California forests are highly biodiverse in wildlife reservoirs and arthropod vectors that may propagate rickettsial pathogens in nature. The proximity of small rural communities to these forests puts people and domestic animals at risk of vector-borne infection due to spillover from wildlife. The current study was conducted to document exposure to rickettsial pathogens in people and domestic animals in a rural community, and identify which rickettsiae are present in sylvatic and peri-domestic environments near this community. Blood samples from people, domestic animals (dogs, cats, and horses) and wild carnivores were tested for Rickettsia spp. antibodies and DNA (people and domestic animals only) by serology and real time (RT)-PCR, respectively. Ectoparasites were collected from dogs, wild carnivores and from vegetation by flagging, and tested for Rickettsia spp. DNA by RT-PCR. DNA sequencing of the rickettsial 17. kDa protein gene or the ompA gene was used for species identification. Despite a seroprevalence of 3% in people, 42% in dogs, 79% in cats, 33% in gray foxes, and 83% in bobcats, RT-PCR on blood was consistently negative, likely because the sensitivity of this test is low, as Rickettsia spp. do not often circulate in high numbers in the blood. Rickettsia spp. DNA was found in four flea species collected from bobcats and Ctenocephalides felis collected from domestic dogs. All amplicons sequenced from fleas were R. felis. Ixodes pacificus collected by flagging were commonly infected with a Rickettsia sp. endosymbiont. Rickettsia rhipicephali DNA was found in Dermacentor variabilis from dogs, black bears, a gray fox, and a D. occidentalis collected by flagging. Dermacentor variabilis from dogs and black bears also contained R. montanensis DNA. Multiple Rickettsia spp. (including species with zoonotic and pathogenic potential) were found among human biting arthropod vectors of both wild and domestic carnivores and on flags. Knowledge of the diversity of Rickettsia spp. that are present within arthropod vectors to which people and domestic animals are exposed is an essential first step is making an accurate diagnosis and in better understanding the epidemiology of these potential pathogens. Within-host and vector interaction among these species may play a role in spillover into human and domestic animals. © 2017 Elsevier GmbH.


Gabriel M.W.,Integral Ecology Research Center | Gabriel M.W.,University of California at Davis | Woods L.W.,University of California at Davis | Poppenga R.,University of California at Davis | And 10 more authors.
PLoS ONE | Year: 2012

Anticoagulant rodenticide (AR) poisoning has emerged as a significant concern for conservation and management of non-target wildlife. The purpose for these toxicants is to suppress pest populations in agricultural or urban settings. The potential of direct and indirect exposures and illicit use of ARs on public and community forest lands have recently raised concern for fishers (Martes pennanti), a candidate for listing under the federal Endangered Species Act in the Pacific states. In an investigation of threats to fisher population persistence in the two isolated California populations, we investigate the magnitude of this previously undocumented threat to fishers, we tested 58 carcasses for the presence and quantification of ARs, conducted spatial analysis of exposed fishers in an effort to identify potential point sources of AR, and identified fishers that died directly due to AR poisoning. We found 46 of 58 (79%) fishers exposed to an AR with 96% of those individuals having been exposed to one or more second-generation AR compounds. No spatial clustering of AR exposure was detected and the spatial distribution of exposure suggests that AR contamination is widespread within the fisher's range in California, which encompasses mostly public forest and park lands Additionally, we diagnosed four fisher deaths, including a lactating female, that were directly attributed to AR toxicosis and documented the first neonatal or milk transfer of an AR to an altricial fisher kit. These ARs, which some are acutely toxic, pose both a direct mortality or fitness risk to fishers, and a significant indirect risk to these isolated populations. Future research should be directed towards investigating risks to prey populations fishers are dependent on, exposure in other rare forest carnivores, and potential AR point sources such as illegal marijuana cultivation in the range of fishers on California public lands.


Stephenson N.,University of California at Davis | Higley J.M.,Hoopa Tribal Forestry | Chomel B.B.,University of California at Davis | Brown R.N.,Humboldt State University | Foley J.E.,University of California at Davis
Vector-Borne and Zoonotic Diseases | Year: 2015

American black bears (Ursus americanus) are common, widely distributed, and broad-ranging omnivorous mammals in northern California forests. Bears may be susceptible to pathogens infecting both domestic animals and humans. Monitoring bear populations, particularly in changing ecosystems, is important to understanding ecological features that could affect bear population health and influence the likelihood that bears may cause adverse impacts on humans. In all, 321 bears were captured between May, 2001, and October, 2003, and blood samples were collected and tested for multiple zoonotic and vector-borne diseases. We found a PCR prevalence of 10% for Anaplasma phagocytophilum, and a seroprevalence of 28% for Toxoplasma gondii, 26% for Borrelia burgdorferi, 26% for A. phagocytophilum, 8% for Trichinella spiralis, 8% for Francisella tularensis and 1% for Yersinia pestis. In addition, we tested bears for pathogens of domestic dogs and found a seroprevalence of 15% for canine distemper virus and 0.6% for canine parvovirus. Our findings show that black bears can become infected with pathogens that are an important public health concern, as well as pathogens that can affect both domestic animals and other wildlife species. © 2015 Mary Ann Liebert, Inc.


Gabriel M.W.,Integral Ecology Research Center | Gabriel M.W.,University of California at Davis | Wengert G.M.,Integral Ecology Research Center | Wengert G.M.,University of California at Davis | And 7 more authors.
Journal of Wildlife Diseases | Year: 2010

Wildlife managers often need to assess the current health status of wildlife communities before implementation of management actions involving surveillance, reintroductions, or translocations. We estimated the sensitivity and specificity of a commercially available domestic canine rapid diagnostic antigen test for canine parvovirus and a rapid enzyme-linked immunosorbent assay for the detection of antibodies toward Anaplasma phagocytophilum on populations of fishers (Martes pennanti) and sympatric gray foxes (Urocyon cinereoargenteus). Eighty-two fecal samples from 66 fishers and 16 gray foxes were tested with both SNAP®PARVO rapid diagnostic test (RDT) and a nested polymerase chain reaction (PCR). Whole blood samples from 23 fishers and 53 gray foxes were tested with both SNAP 4Dx® RDT and immunofluorescence assays (IFAs). The SNAP PARVO RDT detected no parvovirus, whereas PCR detected the virus in 17 samples. Eleven samples were positive using the SNAP 4Dx RDT, whereas 46 samples tested by IFA were positive for A. phagocytophilum. Both RDTs had low sensitivity and poor test agreement. These findings clearly demonstrate the importance of validating RDTs developed for domesticated animals before using them for wildlife populations. © Wildlife Disease Association 2010.


Gabriel M.W.,Integral Ecology Research Center | Gabriel M.W.,University of California at Davis | Woods L.W.,University of California at Davis | Wengert G.M.,Integral Ecology Research Center | And 16 more authors.
PLoS ONE | Year: 2015

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.


Wengert G.M.,University of California at Davis | Gabriel M.W.,Integral Ecology Research Center | Matthews S.M.,Wildlife Conservation Society | Higley J.M.,Hoopa Tribal Forestry | And 10 more authors.
Journal of Wildlife Management | Year: 2014

Interspecific killing is common among carnivores and can have population-level effects on imperiled species. The fisher (Pekania [Martes] pennanti) is a rare forest carnivore in western North America and a candidate for listing under the United States Endangered Species Act. Interspecific killing and intraguild predation are poorly understood in fishers and potential threats to existing western populations. We studied the prevalence and patterns of interspecific killing of fishers in the southern Sierra Nevada and Coastal Range of California. We collected forensic evidence and samples from the carcasses and predation sites, conducted full necropsies when possible, and used molecular methods to determine species of predators responsible for killing fishers. We recovered 101 (59 female, 42 male) fisher carcasses; for 62 (61%) carcasses, we attributed cause of death to interspecific killing. We found that bobcats (Lynx rufus, n = 25 fisher mortalities), mountain lions (Puma concolor, n = 20), and coyotes (Canis latrans, n = 4) were predators of fishers in our study areas. Bobcats killed only female fishers, whereas mountain lions more frequently killed male than female fishers, confirming our hypothesis that female fishers would suffer lethal attacks by smaller predators than would male fishers. Coyotes rarely killed fishers. We found differences in pathologic characteristics of the predation events among the 3 predator species, which may be helpful in identifying predator species. © 2014 The Wildlife Society.


PubMed | Hoopa Tribal Forestry, Wildlife Investigations Laboratory, Integral Ecology Research Center, Humboldt State University and 4 more.
Type: Journal Article | Journal: PloS one | Year: 2015

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.


Matthews S.M.,Wildlife Conservation Society | Matthews S.M.,University of Massachusetts Amherst | Higley J.M.,Hoopa Tribal Forestry | Yaeger J.S.,Hoopa Tribal Forestry | And 2 more authors.
Wildlife Society Bulletin | Year: 2011

We used a mark-resight design to calculate density estimates of fisher (Martes pennanti), a candidate for listing under the United States Endangered Species Act, on the Hoopa Valley Indian Reservation in northwestern California, USA in order to determine population status in 1998 and 2005. Our density estimation results and simultaneous population-monitoring data provided a post hoc opportunity to evaluate the relative efficacy of 3 classical indexing techniques (catch-per-unit-effort, frequency of detection at camera stations, and frequency of detection at track-plate stations) and small-scale occupancy estimation to accurately detect population change. We calculated densities (and 95% CI) of 52 (43-64) and 14 (13-16) fishers/100 km 2 in 1998 and 2005, respectively. We detected a decline in the relative abundance of fishers between 1998 and 2005 using catch-per-unit-effort indices (x 2 ≥ 10.18, P ≤ 0.007), but not in magnitude similar to our density estimates. We detected an increase (x 2 = 4.23, P = 0.040) and no difference (x 2 = 1.38, P = 0.240) in the relative abundance of fishers between surveys using frequency of detection indices at camera stations and at track-plate stations, respectively. Occupancy estimates did not differ between 1998 and 2005. We speculate changes in prey habitat, increases in predation, disease, or some combination of these potential causes, were responsible for the population decline. Our results reinforce the importance of careful thought given to the study goals and potential limitations of any technique. For populations deemed valuable (e.g., at risk or sensitive), we suggest managers consider adopting more defensible, large-scale occupancy estimation or mark-recapture methods to monitor changes in population sizes. © 2011 The Wildlife Society.


Matthews S.M.,Wildlife Conservation Society | Higley J.M.,Hoopa Tribal Forestry | Rennie K.M.,Hoopa Tribal Forestry | Green R.E.,Hoopa Tribal Forestry | And 4 more authors.
Journal of Mammalogy | Year: 2013

Many demographic parameters of imperiled fishers (Martes pennanti) in the Pacific Northwest remain poorly understood but are necessary to develop conservation strategies; herein we report on fisher reproduction, recruitment, and dispersal on the Hoopa Valley Indian Reservation, California, to help fill key knowledge gaps. Forty radiocollared, breeding-age females exhibited denning behavior on 80 (87%) of 92 opportunities between 2005 and 2011. Twenty-eight female fishers weaned offspring in 55 (65%) of 85 adequately monitored denning opportunities. Two-year-old female fishers were less likely than older females to den and wean kits. We counted 52, and extracted and marked 51, kits comprising 28 litters of 19 females between 2005 and 2008. Average litter size was 1.9 kits (27 females, 24 males, and 1 unknown) 4-12 weeks postbirth. Mean distances between natal dens and centroids of newly established ranges for 7 juvenile females was 4.0 km (range = 0.8-18.0 km); this distance for 1 male was 1.3 km. The recruitment rate of juveniles that successfully established a home range per adult female was 0.19 (0.16 for females and 0.02 for males). Our results suggest that managers should work toward increasing female survival rates and consider translocations to increase and expand existing fisher populations. © 2013 American Society of Mammalogists.


Matthews S.M.,Wildlife Conservation Society | Higley J.M.,Hoopa Tribal Forestry | Finn J.T.,University of Massachusetts Amherst | Rennie K.M.,Hoopa Tribal Forestry | And 6 more authors.
Journal of Mammalogy | Year: 2013

Conservation concern for fishers (Pekania Martes pennanti) in the Pacific states has highlighted a need to develop cost-effective methods of monitoring reproduction in extant and reintroduced fisher populations. We evaluated the efficacy of nipple size as a predictive index of weaning success for females with known reproductive histories from 3 study areas in California. We captured and radiocollared 91 female fishers on 146 occasions between 2004 and 2011 and measured the width and height of all 4 nipples and quantified reproductive status via radiotelemetry. We classified each radiomarked female into 1 of 3 reproductive classes (nonbreeders, attempted breeders, and current breeders) based on our telemetry observations during the den season prior to capture. We used a modified random forests (RF) procedure to account for repeated measures of individual females sampled in multiple years. Our modified RF procedure correctly classified reproductive class for 130 (89%) and 131 (90%) of our 146 observations using raw and weighted vote totals, respectively. We calculated Cohen's kappa of 0.80 and 0.81 using raw and weighted vote totals, respectively, indicating strong model performance. We conclude that nipple sizes of female fishers measured during a livetrapping effort can be used as a cost-effective index of the weaning rates of adult female fishers. © 2013 American Society of Mammalogists.

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