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Mitigating human-caused mortality for large carnivores is a pressing global challenge for wildlife conservation. However, mortality is almost exclusively studied at local (within-population) scales creating a mismatch between our understanding of risk and the spatial extent most relevant to conservation and management of wide-ranging species. Here, we quantified mortality for 590 radio-collared mountain lions statewide across their distribution in California to identify drivers of human-caused mortality and investigate whether human-caused mortality is additive or compensatory. Human-caused mortality, primarily from conflict management and vehicles, exceeded natural mortality despite mountain lions being protected from hunting. Our data indicate that human-caused mortality is additive to natural mortality as population-level survival decreased as a function of increasing human-caused mortality and natural mortality did not decrease with increased human-caused mortality. Mortality risk increased for mountain lions closer to rural development and decreased in areas with higher proportions of citizens voting to support environmental initiatives. Thus, the presence of human infrastructure and variation in the mindset of humans sharing landscapes with mountain lions appear to be primary drivers of risk. We show that human-caused mortality can reduce population-level survival of large carnivores across large spatial scales, even when they are protected from hunting.

We conducted a range-wide investigation of the dynamics of site-level reproductive rate of northern spotted owls using survey data from 11 study areas across the subspecies geographic range collected during 1993-2018. Our analytical approach accounted for imperfect detection of owl pairs and misclassification of successful reproduction (i.e., at least one young fledged) and contributed further insights into northern spotted owl population ecology and dynamics. Both nondetection and state misclassification were important, especially because factors affecting these sources of error also affected focal ecological parameters. Annual probabilities of site occupancy were greatest at sites with successful reproduction in the previous year and lowest for sites not occupied by a pair in the previous year. Site-specific occupancy transition probabilities declined over time and were negatively affected by barred owl presence. Overall, the site-specific probability of successful reproduction showed substantial year-to-year fluctuations and was similar for occupied sites that did or did not experience successful reproduction the previous year. Site-specific probabilities for successful reproduction were very small for sites that were unoccupied the previous year. Barred owl presence negatively affected the probability of successful reproduction by northern spotted owls in Washington and California, as predicted, but the effect in Oregon was mixed. The proportions of sites occupied by northern spotted owl pairs showed steep, near-monotonic declines over the study period, with all study areas showing the lowest observed levels of occupancy to date. If trends continue it is likely that northern spotted owls will become extirpated throughout large portions of their range in the coming decades.

Significance Invasive species can cause extinctions of native species and widespread biodiversity loss. Invader removal is a common management response, but the use of long-term field experiments to characterize effectiveness of removals in benefitting impacted native species is rare. We used a large-scale removal experiment to investigate the demographic response of a threatened native species, the northern spotted owl, to removal of an invasive competitor species, the barred owl. Removal of barred owls had a strong, positive effect on survival of spotted owls, which arrested long-term population declines of spotted owls. The results demonstrate that the long-term persistence of spotted owls will depend heavily on reducing the negative impacts of barred owls while simultaneously addressing other threats, such as habitat loss., Changes in the distribution and abundance of invasive species can have far-reaching ecological consequences. Programs to control invaders are common but gauging the effectiveness of such programs using carefully controlled, large-scale field experiments is rare, especially at higher trophic levels. Experimental manipulations coupled with long-term demographic monitoring can reveal the mechanistic underpinnings of interspecific competition among apex predators and suggest mitigation options for invasive species. We used a large-scale before–after control–impact removal experiment to investigate the effects of an invasive competitor, the barred owl (Strix varia), on the population dynamics of an iconic old-forest native species, the northern spotted owl (Strix occidentalis caurina). Removal of barred owls had a strong, positive effect on survival of sympatric spotted owls and a weaker but positive effect on spotted owl dispersal and recruitment. After removals, the estimated mean annual rate of population change for spotted owls stabilized in areas with removals (0.2% decline per year), but continued to decline sharply in areas without removals (12.1% decline per year). The results demonstrated that the most substantial changes in population dynamics of northern spotted owls over the past two decades were associated with the invasion, population expansion, and subsequent removal of barred owls. Our study provides experimental evidence of the demographic consequences of competitive release, where a threatened avian predator was freed from restrictions imposed on its population dynamics with the removal of a competitively dominant invasive species.

Selection of habitat characteristics by reproductive females during neonate development can mediate the influence of adverse environmental conditions on the fitness of offspring. Previous research has suggested that cavities and burrows used for reproduction by cavity-obligate species offer thermoregulatory benefits, access to prey, and can limit predation pressure. As fishers (Pekania pennanti) are secondary cavity-obligate breeders, we hypothesized that they select particular characteristics of reproductive den cavities at discrete stages of offspring development to mediate adverse biotic and environmental effects on their neonates. To test our hypothesis, we located 406 reproductive dens and 154 cavity rest sites used by 65 individual adult female fishers during 11 reproductive seasons (2005–2016) in northwestern California. We counted 53 (27 F, 26 M) kits in 31 litters born to 19 females during six of these reproductive seasons. The weight of kits varied significantly by sex and by age, whereas the length of kits varied only by age, suggesting that adult females in this population might be preferentially investing in male kits. We found that natal and early-maternal dens buffered minimum temperatures significantly more than late-maternal dens and cavities used during the nonreproductive season. A male fisher skull was also less likely to fit through the cavity openings of natal dens than through the openings of cavities used by adult females during the nonreproductive season. Litter survival was significantly lower at natal dens than at late-maternal dens. The age of adult female fishers did not affect the probability of litter survival. Our results emphasize the vulnerability of vertebrate offspring during early developmental periods and how cavity-obligate species select cavities to mediate environmental conditions during reproduction.

The northern spotted owl (Strix occidentalis caurina) inhabits older coniferous forests in the Pacific Northwest and has been at the center of forest management issues in this region. The immediate threats to this federally listed species include habitat loss and competition with barred owls (Strix varia), which invaded from eastern North America. We conducted a prospective meta-analysis to assess population trends and factors affecting those trends in northern spotted owls using 26 years of survey and capture-recapture data from 11 study areas across the owls' geographic range to analyze demographic traits, rates of population change, and occupancy parameters for spotted owl territories. We found that northern spotted owl populations experienced significant declines of 6–9% annually on 6 study areas and 2–5% annually on 5 other study areas. Annual declines translated to ≤35% of the populations remaining on 7 study areas since 1995. Barred owl presence on spotted owl territories was the primary factor negatively affecting apparent survival, recruitment, and ultimately, rates of population change. Analysis of spotted and barred owl detections in an occupancy framework corroborated the capture-recapture analyses with barred owl presence increasing territorial extinction and decreasing territorial colonization of spotted owls. While landscape habitat components reduced the effect of barred owls on these rates of decline, they did not reverse the negative trend. Our analyses indicated that northern spotted owl populations potentially face extirpation if the negative effects of barred owls are not ameliorated while maintaining northern spotted owl habitat across their range.

The literature on ecosystem services has been criticized for inadequately acknowledging culture values and for de‐emphasizing economic disservices. While economic loss due to tree damage by American black bears (Ursus americanus, hereafter bears) may negatively affect timber production, it also alters forest structure and habitat that may contribute to forest wildlife diversity, including culturally significant species. We examined the relationship between bear damage to Douglas‐fir trees (Pseudotsuga menziesii var. menziesii) and response of cavity‐nesting birds on the Hoopa Valley Indian Reservation. We measured disservices from bear damage by calculating current and future timber revenue loss, and ecosystem services by calculating forest structural complexity, abundance and diversity of cavity‐nesting birds, and woodpecker activity. Bear damage was correlated negatively with tree growth and positively with estimated timber loss. Forest structural complexity was positively correlated with bear damage, and cavity‐nester abundance and woodpecker foraging activity were positively correlated with forest structural complexity and bear damage. Pileated woodpeckers (Dryocopus pileatus) and red‐breasted sapsuckers (Sphyrapicus ruber) used bear‐damaged trees out of proportion to their availability, and pileated woodpeckers selected for more structurally complex sample units. Information from this study advances our understanding of the potential for bear foraging to negatively affect economic revenue and the trade‐offs with habitat conditions favoring other important wildlife species. Understanding the costs and benefits of bear damage can help guide management decisions vital to forest managers both on and off tribal lands.

Slow ecological processes challenge conservation. Short-term variability can obscure the importance of slower processes that may ultimately determine the state of a system. Furthermore, management actions with slow responses can be hard to justify. One response to slow processes is to explicitly concentrate analysis on state dynamics. Here, we focus on identifying drivers of Northern Spotted Owl (Strix occidentalis caurina) territorial occupancy dynamics across 11 study areas spanning their geographic range and forecasting response to potential management actions. Competition with Barred Owls (Strix varia) has increased Spotted Owl territory extinction probabilities across all study areas and driven recent declines in Spotted Owl populations. Without management intervention, the Northern Spotted Owl subspecies will be extirpated from parts of its current range within decades. In the short term, Barred Owl removal can be effective. Over longer time spans, however, maintaining or improving habitat conditions can help promote the persistence of northern spotted owl populations. In most study areas, habitat effects on expected Northern Spotted Owl territorial occupancy are actually greater than the effects of competition from Barred Owls. This study suggests how intensive management actions (removal of a competitor) with rapid results can complement a slower management action (i.e., promoting forest succession).

The literature on fishers - medium-sized, North American carnivores - is broad, despite being limited, and traditional ecological knowledge of Native Americans contributes to our understanding of fishers. Fishers are generalist predators but also specialized predators of North American porcupines. Over trapping, habitat loss and climate change reduced fisher populations after European colonization of North America. Protection and reintroductions led to general but not to universal population recovery, contributing to the understanding of reintroduction science, including population genetics of both rare and expanding populations. Although adapted to live in old forests with complex structure, some fishers have colonized fragmented habitats, including suburbs. Models of fisher habitat, energetics, sexual dimorphism, genetics, and use of space illustrate the diversity of approaches possible for carnivore studies. Thus, the fisher has become a model organism for ecological and conservation research on mammalian carnivores.

Estimates of species' vital rates and an understanding of the factors affecting those parameters over time and space can provide crucial information for management and conservation. We used mark-recapture, reproductive output, and territory occupancy data collected during 1985-2013 to evaluate population processes of Northern Spotted Owls (Strix occidentalis caurina) in 11 study areas in Washington, Oregon, and northern California, USA. We estimated apparent survival, fecundity, recruitment, rate of population change, and local extinction and colonization rates, and investigated relationships between these parameters and the amount of suitable habitat, local and regional variation in meteorological conditions, and competition with Barred Owls (Strix varia). Data were analyzed for each area separately and in a meta-analysis of all areas combined, following a strict protocol for data collection, preparation, and analysis. We used mixed effects linear models for analyses of fecundity, Cormack-Jolly-Seber open population models for analyses of apparent annual survival (phi), and a reparameterization of the Jolly-Seber capture-recapture model (i.e. reverse Jolly-Seber; RJS) to estimate annual rates of population change (lambda(RJS)) and recruitment. We also modeled territory occupancy dynamics of Northern Spotted Owls and Barred Owls in each study area using 2-species occupancy models. Estimated mean annual rates of population change (lambda) suggested that Spotted Owl populations declined from 1.2% to 8.4% per year depending on the study area. The weighted mean estimate of lambda for all study areas was 0.962 (+/- 0.019 SE; 95% CI: 0.925-0.999), indicating an estimated range-wide decline of 3.8% per year from 1985 to 2013. Variation in recruitment rates across the range of the Spotted Owl was best explained by an interaction between total winter precipitation and mean minimum winter temperature. Thus, recruitment rates were highest when both total precipitation (29 cm) and minimum winter temperature (-9.5 degrees C) were lowest. Barred Owl presence was associated with increased local extinction rates of Spotted Owl pairs for all 11 study areas. Habitat covariates were related to extinction rates for Spotted Owl pairs in 8 of 11 study areas, and a greater amount of suitable owl habitat was generally associated with decreased extinction rates. We observed negative effects of Barred Owl presence on colonization rates of Spotted Owl pairs in 5 of 11 study areas. The total amount of suitable Spotted Owl habitat was positively associated with colonization rates in 5 areas, and more habitat disturbance was associated with lower colonization rates in 2 areas. We observed strong declines in derived estimates of occupancy in all study areas. Mean fecundity of females was highest for adults (0.309 +/- 0.027 SE), intermediate for 2-yr-olds (0.179 +/- 0.040 SE), and lowest for 1-yr-olds (0.065 +/- 0.022 SE). The presence of Barred Owls and habitat covariates explained little of the temporal variation in fecundity in most study areas. Climate covariates occurred in competitive fecundity models in 8 of 11 study areas, but support for these relationships was generally weak. The fecundity meta-analysis resulted in 6 competitive models, all of which included the additive effects of geographic region and annual time variation. The 2 top-ranked models also weakly supported the additive negative effects of the amount of suitable core area habitat, Barred Owl presence, and the amount of edge habitat on fecundity. We found strong support for a negative effect of Barred Owl presence on apparent survival of Spotted Owls in 10 of 11 study areas, but found few strong effects of habitat on survival at the study area scale. Climate covariates occurred in top or competitive survival models for 10 of 11 study areas, and in most cases the relationships were as predicted; however, there was little consistency among areas regarding the relative importance of specific climate covariates. In contrast, meta-analysis results suggested that Spotted Owl survival was higher across all study areas when the Pacific Decadal Oscillation (PDO) was in a warming phase and the Southern Oscillation Index (SOI) was negative, with a strongly negative SOI indicative of El Nino events. The best model that included the Barred Owl covariate (BO) was ranked 4th and also included the PDO covariate, but the BO effect was strongly negative. Our results indicated that Northern Spotted Owl populations were declining throughout the range of the subspecies and that annual rates of decline were accelerating in many areas. We observed strong evidence that Barred Owls negatively affected Spotted Owl populations, primarily by decreasing apparent survival and increasing local territory extinction rates. However, the amount of suitable owl habitat, local weather, and regional climatic patterns also were related to survival, occupancy (via colonization rate), recruitment, and, to a lesser extent, fecundity, although there was inconsistency in regard to which covariates were important for particular demographic parameters or across study areas. In the study areas where habitat was an important source of variation for Spotted Owl demographics, vital rates were generally positively associated with a greater amount of suitable owl habitat. However, Barred Owl densities may now be high enough across the range of the Northern Spotted Owl that, despite the continued management and conservation of suitable owl habitat on federal lands, the long-term prognosis for the persistence of Northern Spotted Owls may be in question without additional management intervention. Based on our study, the removal of Barred Owls from the Green Diamond Resources (GDR) study area had rapid, positive effects on Northern Spotted Owl survival and the rate of population change, supporting the hypothesis that, along with habitat conservation and management, Barred Owl removal may be able to slow or reverse Northern Spotted Owl population declines on at least a localized scale. USDA Forest ServiceUnited States Department of Agriculture (USDA)United States Forest Service; USDI Bureau of Land Management; USDI National Park Service; Green Diamond Resource Company; Plum Creek Timber Company; Louisiana Pacific Lumber Company; Hancock Forest Management; Hoopa Tribe; USDI Bureau of Land Management via a Cost Reimbursable Research Agreement with Oregon State University Funding for demographic studies of Northern Spotted Owls on federal lands was provided primarily by the USDA Forest Service, USDI Bureau of Land Management, and USDI National Park Service. Funding for studies on nonfederal lands came from the Green Diamond Resource Company, Plum Creek Timber Company, Louisiana Pacific Lumber Company, Hancock Forest Management, and the Hoopa Tribe. Funding for the workshop was provided by the USDA Forest Service and USDI Bureau of Land Management via a Cost Reimbursable Research Agreement with Oregon State University. The U.S. Geological Survey and USDA Forest Service required approval of the final manuscript before publication, but none of the funding agencies associated with this meta-analysis had any influence on the content of the submitted or published manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Ethics statement: All data from study areas in which K.M.D., E.D.F., and A.B.F. were principal investigators (CLE, OLY, COA, HJA, TYE, CAS, and NWC) were collected following protocols approved under animal care and use permits overseen by Oregon State University's and Colorado State University's Institutional Animal Care and Use Committees. These protocols were followed and all relevant state and federal permits were acquired and maintained for all study areas included in this meta-analysis. Public domain – authored by a U.S. government employee

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.

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.

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.

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 km2 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 (χ2 ≥ 10.18, P ≤ 0.007), but not in magnitude similar to our density estimates. We detected an increase (χ2 = 4.23, P = 0.040) and no difference (χ2 = 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.

Accurate and precise population estimates are necessary to answer many management questions, but these estimates are generally unavailable for large carnivores because of their extensive movements, low densities, and secretive natures. These traits also often prevent the bounding of occupied areas necessary to estimate densities. We used a modified Petersen mark–recapture methodology to estimate black bear density in 1998 at 2 study sites on the Hoopa Valley Reservation, California, from mark–resight data. We used culvert traps to capture, radiocollar, and eartag bears, radio telemetry to establish closure, and remote cameras to collect resighting data. We calculated bear densities (90% confidence intervals) of 0.18 (0.09–0.32) and 1.33 (0.54–3.29) bears/km2 on the 2 sites. Knowledge of bear densities can now be incorporated into forest management actions and associated bear control measures on the Hoopa Valley Reservation.

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.

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.

Although granulocytic anaplasmosis, caused by infection of Anaplasma phagocytophilum, is an emerging human and domestic animal disease, the ecology and natural history of the parasite is not well understood. Gray foxes (Urocyon cinereoargenteus) are relatively common, occasionally peri-urban mesocarnivores whose geographic distribution overlaps the reported distribution of granulocytic anaplasmosis in humans and domestic animals in North America. We evaluated the potential of foxes as hosts and reservoirs of A. phagocytophilum in both urban and backcountry habitats of the Hoopa Valley Indian Reservation, Humboldt County, California, USA. We trapped 54 individual foxes and had 16 recaptures for a total of 70 fox samples between June 2003 and October 2004 in delineated urban and backcountry zones. We collected 296 adult and 145 nymphal ticks from the 70 captured foxes including 193 Ixodes pacificus, 149 Ixodes texanus, 98 Dermacentor variabilis, and one Dermacentor occidentalis. There were seasonal differences in tick intensities, with most I. pacificus adults occurring in winter and spring (P < 0.001), most I. texanus nymphs in spring (P = 0.03), and most D. variabilis adults in spring and summer (P = 0.01). Thirty-six (51%) of the 70 fox sera had antibodies against A. phagocytophilum, with a higher (P = 0.24) prevalence in backcountry foxes (16 of 23) than in urban-zone foxes (12 of 31). Six (9%) of 70 fox samples were polymerase chain reaction-positive for A. phagocytophilum. Twenty-eight (31%) of 90 domestic dogs sampled from vaccine clinics within the study area were seropositive for A. phagocytophilum. There was a significant difference in prevalence between dogs and backcountry foxes (70%), but no differences were found between dogs and urban foxes (39%). We propose that gray foxes are a good sentinel species for A. phagocytophilum infections in northwestern California.

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.