Evidence for Depressed Reproduction of Golden Eagles in Washington

Beginning in 1977 the Washington Department of Fish and Wildlife conducted annual surveys to determine statewide golden eagle (Aquila chrysaetos) occupancy and productivity. Current interest in the regional and national status of the species prompted our investigation to determine utility of historical data in assessing trends in reproduction, and to test efficacy of a sampling protocol that surveyed randomly selected territories and also accounted for detection probability. We found evidence indicating poor reproduction from 38 annual surveys conducted at 301 known territories statewide between 1977 and 2014. At 256 territories in eastern Washington, USA, apparent occupancy was low ( = 50.9%) and nesting success declined by 22%. All reproductive parameters were higher than at 45 territories in western Washington. We tested efficacy of a sampling protocol in 2013 and 2014 by surveying 108 randomly selected eastern territories. Probability of detecting eagles for these years from ground (= 89%) was greater than from air (= 66%). Our estimate of territory occupancy, corrected by probability of detection, was lower in 2013 (= 56.7%, 95% CI = 46.3–66.7%) than in 2014 (= 73.7%, 95% CI = 64.8–81.7%), as was the estimated number of breeding pairs (2013: = 158, 95% CI = 151–164; 2014: = 187, 95% CI = 182–192). Higher productivity (young/occupied territory) in 2013 (= 0.59, 95% CI = 0.40–0.82) than in 2014 (= 0.41, 95% CI = 0.27–0.59) and lower proportions of ≥1 immature eagle among nesting pairs in 2013 (16%) than in 2014 (31%), suggested higher immature pairing among sampled pairs contributed to inter-year differences in these reproductive parameters. Current and historical evidence for depressed golden eagle nesting in Washington is consistent with documented effects from habitat conversion, prey declines, lead contamination, and wind power development. We recommend future surveys in eastern Washington adhere to the random sampling protocol and conduct surveys at regular intervals to allow for trend analysis of reproductive parameters to better monitor golden eagle status. Surveys in western Washington, conducted exclusively from ground at all nests, will improve detection and cost efficiency. © 2020 The Wildlife Society.     

Anthropogenic Disturbance and Population Viability of Woodland Caribou in Ontario

One of the most challenging tasks in wildlife conservation and management is to clarify how spatial variation in land cover due to anthropogenic disturbance influences wildlife demography and long-term viability. To evaluate this, we compared rates of survival and population growth by woodland caribou (Rangifer tarandus caribou) from 2 study sites in northern Ontario, Canada that differed in the degree of anthropogenic disturbance because of commercial logging and road development, resulting in differences in predation risk due to gray wolves (Canis lupus). We used an individual-based model for population viability analysis (PVA) that incorporated adaptive patterns of caribou movement in relation to predation risk and food availability to predict stochastic variation in rates of caribou survival. Field estimates of annual survival rates for adult female caribou in the unlogged ( 0.90) and logged ( 0.76) study sites recorded during 2010–2014 did not differ significantly (P > 0.05) from values predicted by the individual-based PVA model (unlogged: = 0.87; logged: 0.79). Outcomes from the individual-based PVA model and a simpler stage-structured matrix model suggest that substantial differences in adult survival largely due to wolf predation are likely to lead to long-term decline of woodland caribou in the commercially logged landscape, whereas the unlogged landscape should be considerably more capable of sustaining caribou. Estimates of population growth rates (λ) for the 2010–2014 period differed little between the matrix model and the individual-based PVA model for the unlogged (matrix model = 1.01; individual-based model = 0.98) and logged landscape (matrix model = 0.88; individual-based model = 0.89). We applied the spatially explicit PVA model to assess the viability of woodland caribou across 14 woodland caribou ranges in Ontario. Outcomes of these simulations suggest that woodland caribou ranges that have experienced significant levels of commercial forestry activities in the past had annual growth rates <0.89, whereas caribou ranges that had not experienced commercial forestry operations had population growth rates >0.96. These differences were strongly related to regional variation in wolf densities. Our results suggest that increased wolf predation risk due to anthropogenic disturbance is of sufficient magnitude to cause appreciable risk of population decline in woodland caribou in Ontario. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Sarcoptes mange (Sarcoptes scabiei) increases diurnal activity of bare-nosed wombats (Vombatus ursinus) in an agricultural riparian environment

Sarcoptes mange is an important disease that affects the health, mobility and longevity of bare-nosed wombats (Vombatus ursinus) in Australia. We measured the activity patterns of wombats infected with varying levels of mange in an agricultural riparian environment using motion-sensing cameras. Over a 10 month period we observed a greater increase in nocturnal activity of mange-free wombats than those with mange on six or more body sections. The percentage of mange-infected wombats was greater during the day, but in the 6 h after midnight, wombats were detected with fewer mange-infected segments. Air temperature at the time of wombat detections was generally higher for individuals with mange than those without mange. Our results show that diurnal activity of wombats is likely to increase with higher levels of infection by sarcoptes mange. Increased diurnal activity is likely to present serious problems for the persistence of sustainable populations of wild wombats.     

Optimal Strategies for Managing Wildlife Harvest Under System Change

Wildlife populations are experiencing shifting dynamics due to climate and landscape change. Management policies that fail to account for non-stationary dynamics may fail to achieve management objectives. We establish a framework for understanding optimal strategies for managing a theoretical harvested population under non-stationarity. Building from harvest theory, we develop scenarios representing changes in population growth rate () or carrying capacity () and derive time-dependent optimal harvest policies using stochastic dynamic programming. We then evaluate the cost of falsely assuming stationarity by comparing the outcomes of forward projections in which either the optimal policy or a stationary policy is applied. When declines over time, the stationary policy leads to an underharvest of the population, resulting in less harvest over the short term but leaving the population in a higher-value state. When declines over time, the stationary policy leads to overharvest, resulting in greater harvest returns in the short term but leaving the population in a lower and potentially more vulnerable state. This work demonstrates the basic properties of time-dependent harvest management and provides a framework for evaluating the many outstanding questions about optimal management strategies under climate change. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.     

Road impacts a tipping point for wildlife populations in threatened landscapes

The conservation of wildlife populations living adjacent to roads is gaining international recognition as a worldwide concern. Populations living in road-impacted environments are influenced by spatial parameters including the amount and arrangement of suitable habitat. Similarly, heterogeneity in threatening processes can act at a variety of spatial scales and be crucial in affecting population persistence. Common wombats (Vombatus ursinus) are considered both widespread and abundant throughout their eastern Australian continental distribution. They nevertheless face many threats, primarily human induced. As well as impacts from disease and predation by introduced species, high roadside fatality rates on many rural roads are frequently reported. We parameterized a model for common wombat population viability analysis within a 750-km² area of the northwestern corner of Kosciuszko National Park in New South Wales, Australia, and tested its sensitivity to changes in the values of basic parameters. We then assessed the relative efficiency of various mitigation measures by examining the combined impact from roads, disease and predation on wombat subpopulation persistence in the area. We constructed a stage-structured and spatially explicit model incorporating estimates of survival and fecundity parameters for each of the identified subpopulations using RAMAS GIS. Estimates of current threatening processes suggest mitigating road-kill is the most effective management solution. Results highlight the importance of recognizing the interplay between various threats and how their combination has the capacity to drive local depletion events.     

Sarcoptes scabei var. wombati infection in the common wombat (Vombatus ursinus)

Sarcoptic mange has been identified as the most significant infectious disease affecting the common wombat (Vombatus ursinus). Biochemistry and haematology values for wild common wombats have not been published previously. A 35% of the wombat population were exhibiting clinical signs of the disease. Significant changes in blood haematology and biochemistry parameters were observed in affected animals. A seasonal variation in numbers of animals affected was demonstrated. Females appeared to be more commonly affected than males although the reason for this is not forthcoming.     

Bobcat Hair Cortisol Correlates with Land Use and Climate

Bobcats (Lynx rufus) have been increasing in abundance in the northeast United States despite a corresponding trend of increased anthropogenic land uses. Inhabiting areas of high human land use can affect stress levels, and hence cortisol titers, for wildlife species by increasing frequency of human interaction and altering habitats. In turn, increased cortisol levels can have negative effects at the individual and population level including decreased immune function, slowed growth and tissue repair, reduced reproductive capacity, and nutritional deficiencies. We quantified cortisol in bobcats across New Hampshire and Vermont, USA, using hair samples, then explored associations between hair cortisol and various organismal, land use, land cover, and climatic variables at 2 different spatial scales. Hair cortisol differed by season and bobcat mass. On average, cortisol levels were higher in fall than in spring, and larger bobcats had lower cortisol levels. Anthropogenic land uses—especially residential and agricultural uses—were the most important predictors of hair cortisol at the town scale ( area = 93 km²). At a larger scale (Wildlife Management Units; area = 1,256 km²), temperature and precipitation were better predictors of hair cortisol, suggesting that extreme weather may have significant effects on bobcat population dynamics. Our results highlight the importance of landscape composition and local conditions in the sustainable management of furbearer populations. © 2021 The Wildlife Society.     

Genetic Characteristics of Restored Elk Populations in Kentucky

Translocations are a common management practice to restore or augment populations. Understanding the genetic consequences of translocation efforts is important for the long-term health of restored populations. The restoration of elk (Cervus canadensis) to Kentucky, USA, included source stocks from 6 western states, which were released at 8 sites in southeastern Kentucky during 1997–2002. We assessed genetic diversity in restored herds and compared genetic similarity to source stocks based on 15 microsatellite DNA loci. Genetic variation in the restored populations was comparable to source stocks ( allelic richness = 3.52 and 3.50; expected heterozygosity = 0.665 and 0.661 for restored and source, respectively). Genetic differentiation among all source and restored populations ranged from 0.000 to 0.065 for pairwise F_ST and 0.034 to 0.161 for pairwise Nei's D_A. Pairwise genetic differentiation and Bayesian clustering revealed that stocks from Utah and North Dakota, USA, contributed most to restored populations. Other western stocks appeared less successful and were not detected with our data, though our sampling was not exhaustive. We also inferred natural movements of elk among release sites by the presence of multiple genetic stocks. The success of the elk restoration effort in Kentucky may be due, in part, to the large number of elk (n = 1,548), repeated releases, and use of diverse source stocks. Future restoration efforts for elk in the eastern United States should consider the use of multiple stock sources and a large number of individuals. In addition, preservation of genetic samples of founder stock will enable detailed monitoring in the future. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Liver lesions in the common wombat associated with migrating Taenia hydatigena larvae

Four mature female wombats (Vombatus ursinus) were experimentally infected per os with 10,000 viable eggs of Taenia hydatigena. One wombat was killed and examined on each of days 7, 14, 28 and 56 post-inoculation (PI). Subcapsular haemorrhagic and healing tracks were found in the livers on each day, and on day 56 PI a granuloma, probably a reaction to a degenerating larvae, was evident. There were no signs of further development in the peritoneal cavity and it was concluded that the wombat is probably an aberrant host for this cestode. Similar lesions in the livers of three of seven wombats examined in South Gippsland, Victoria suggested strongly that these had been caused by migrating T. hydatigena larvae.     

A seroprevalence survey of Toxoplasma gondii in common wombats (Vombatus ursinus)

Serum was collected from 23 wild common wombats (Vombatus ursinus) on a pastoral property in the Southern Tablelands of New South Wales, Australia (231N 616E) between 3rd August 2001 and 25th March 2002. The serum was tested using three serological methods for antibodies to Toxoplasma gondii. Six animals (26.1%) were shown to have antibodies to T. gondii. The latex agglutination test proved to be less sensitive than the direct agglutination test or the modified agglutination test. This is the first serological survey of T. gondii in wombats. This is the first recorded use of the latex agglutination test on wombat serum. This study demonstrated the highest percentage of seropositive animals in any serological survey for T. gondii in marsupials.     

Strange bedfellows: Mammal burrow disturbances may provide thermoregulatory microsites for fossorial reptiles in densely vegetated dunes

Burrow excavation by mammals generates heterogeneity within landscapes. Globally, these disturbances are known to provide significant ecosystem benefits. Most investigations of native Australian burrowing mammal disturbances has focused on the role of burrows in landscape function and interspecific thermal refugia. Herein, we present a novel observation of the fossorial skink Lerista bougainvillii utilizing burrow mounds of the common wombat (Vombatus ursinus) for possible thermoregulatory gains. In the early morning, when thermoregulatory opportunities were limited, L. bougainvillii were detected in mounds that appeared hotter than adjoining vegetation. These observations suggest that in densely vegetated habitats thermal heterogeneity caused by mammal burrows may offer important thermoregulatory opportunities for fossorial species with limited climbing capacity.     

Disturbance-Mediated Apparent Competition Decouples in a Northern Boreal Caribou Range

The most widely reported threat to boreal and mountain populations of woodland caribou (Rangifer tarandus caribou; caribou) involves habitat- or disturbance-mediated apparent competition (DMAC). With DMAC, natural and anthropogenic disturbances that increase the abundance of deciduous-browsing cervids (e.g., moose [Alces alces], deer [Odocoileus spp.]) are thought to promote predator (especially wolf [Canis lupus]) numbers, which heightens predation risk to caribou. We know most about the effects of DMAC on caribou where the species is under threat by anthropogenic activities in relatively productive southern boreal and mountain systems. Yet, >60% of extant boreal caribou range in North America consists of northern shield and taiga ecoregions of low productivity where caribou may compete with only 1 ungulate species (moose) in the context of DMAC. In this environment, we know very little of how DMAC acts as a limiting factor to caribou. In Saskatchewan, Canada, from 2014–2018, using a combination of vegetation sampling, aerial surveys, and telemetry data (n = 38 wolves), we searched for evidence of DMAC (trends in data consistent with the hypothesis) in an 87,193-km² section of the Western Boreal Shield, a poorly productive but pristine region (0.18% of land cover classed as an anthropogenic feature) with a historically high fire-return interval (47% of stands aged <40 years). Despite the high levels of disturbance, moose density was relatively low (47 moose/1,000 km²), likely because of the scarcity of deciduous or mixed-wood stands and low abundance of deciduous browse in the young conifer stands that dominated the landscape. In contrast, boreal caribou density was relatively high for the species (37 caribou/1,000 km²). Wolf density (3.1 wolves/1,000 km²) and pack sizes ( = 4.0 wolves/pack) were low and resident (established) territories were large ( = 4,360 km²; 100% minimum convex polygon). The low density of wolves mirrored the low (standardized) ungulate biomass index (UBI; moose + boreal caribou) of the study area (0.36 UBI/km²). We conclude that wolf and hence caribou populations were not responding in accordance with the outcomes generally predicted by DMAC in our study area because the requisite strong, positive response to fire of deciduous-browse and alternate-prey abundance was lacking. As a limiting factor to caribou, DMAC is likely modulated at a macroecological scale by factors such as net primary productivity, a corollary to the general hypothesis that we advance here (i.e., primary productivity hypothesis of DMAC). We caution against managing for caribou based on the presumption of DMAC where the mechanism does not apply, which may include much of boreal caribou range in the north. © 2020 The Wildlife Society.     

Prey Specialization by Cougars on Feral Horses in a Desert Environment

Natural controls on the distribution, abundance, or growth rates of exotic species are a desirable mode of intervention because of lower costs compared to anthropogenic controls and greater social acceptance. In the Great Basin, cougars (Puma concolor) are the most widely distributed carnivore capable of killing large ungulate prey. Populations of feral horses (Equus ferus) are widely distributed throughout the Great Basin and can grow at rates up to 20%/year. Although cougars exhibit distributional overlap with horses, it has been assumed that predation is minimal because of differences in habitat use and body-size limitations. To evaluate this hypothesis, we monitored the diets of 21 global positioning system (GPS)-collared cougars in the western Great Basin (5 males, 8 females) and eastern Sierra Nevada (2 males, 6 females) from 2009–2012. We investigated 1,310 potential kill sites and located prey remains of 820 predation events. We compared prey composition and kill rates of cougars inhabiting the Sierra Nevada and Great Basin, and among male and female cougars across seasons. We used generalized linear mixed models (GLMMs) to examine the effects of prey availability and habitat characteristics on the probability of predation on horses by cougars. Mule deer (Odocoileus hemionus) comprised 91% of prey items killed on the Sierra Nevada reference site but only comprised 29% of prey items in the Great Basin study area. Average annual kill rates for deer differed between the Sierra Nevada ( = 0.85 deer/week, range = 0.44–1.3) and Great Basin ( = 0.21 deer/week, range = 0.00–0.43). Diets of cougars in the Great Basin were composed predominantly of horses (59.6%, n = 460 prey items; 13 individuals). Ten cougars regularly consumed horses, and horses were the most abundant prey in the diet of 8 additional individuals in the Great Basin. Cougars on average killed 0.38 horses/week in the Great Basin (range=0.00–0.94 horses/week). Differences in predation on horses between the sexes of cougars were striking; Great Basin females incorporated more horses across all age classes year-round, whereas male cougars tended to exploit neonatal young during spring and summer before switching to deer during winter. Within GLMM models, the probability of predation on horses compared to other prey species increased with elevation, horse density, and decreasing density of mule deer on the landscape, and was more likely to occur in sagebrush (Artemesia spp.) than in pinyon (Pinus monophylla)–juniper (Juniperus osteosperma) forests. Behavior of individual cougars accounted for more than a third of the variation explained by our top models predicting predation on horses in the Great Basin. At landscape scales, cougar predation is unlikely to limit the growth of feral horse populations. In the Great Basin ecosystem, however, cougars of both sexes successfully preyed on horses of all age classes. Moreover, some reproductive, female cougars were almost entirely dependent on feral horses year-round. Taken together, our data suggest that cougars may be an effective predator of feral horses, and that some of our previous assumptions about this relationship should be reevaluated and integrated into management and planning. © 2021 The Wildlife Society.     

GENETIC VARIATION AMONG STRAINS OF THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM (DINOPHYCEAE)

The toxic dinoflagellate Gymnodinium catenatum Graham has formed recurrent toxic blooms in southeastern Tasmanian waters since its discovery in the area in 1986. Current evidence suggests that this species might have been introduced to Tasmania prior to 1973, possibly in cargo vessel ballast water carried from populations in Japan or Spain, followed by recent dispersal to mainland Australia. To examine this hypothesis, cultured strains from G. catenatum populations in Australia, Spain, Portugal, and Japan were examined using allozymes and randomly amplified polymorphic DNA (RAPD). Allozyme screening detected very limited polymorphism and was not useful for population comparisons; however, Australian, Spanish, Portuguese, and Japanese strains showed considerable RAPD diversity, and all strains examined represented unique genotypes. Multidimensional scaling analysis (MDS) of RAPD genetic distances between strains showed clear separation of strains into three nonoverlapping regional clusters: Australia, Japan, and Spain/Portugal. Analysis of genetic distances between strains from the three regional populations indicated that Australian strains were almost equally related to both the Spanish/Portuguese population and the Japanese population. Analysis of molecular variance (AMOVA) found that genetic variation was partitioned mainly within populations (87%) compared to the variation between the regions (8%) and between populations within regions (5%). The potential source population for Tasmania’s introduced G. catenatum remains equivocal; however, strains from the recently discovered mainland Australian population (Port Lincoln, South Australia, 1996) clustered with Tasmanian strains, supporting the notion of a secondary relocation of Tasmanian G. catenatum populations to the mainland via a shipping vector. Geographic and temporal clustering of strains was evident among the Tasmanian strains, indicating that genetic exchange between neighboring estuaries is limited and that Tasmanian G. catenatum blooms are composed of localized, estuary-bound subpopulations.     

Eagle visitation rates to carrion in a winter scavenging guild

Understanding the behavioral ecology of species of conservation concern can help to inform better management. During winters 2011 through 2017, we placed camera traps at stations baited with carrion to investigate characteristics of winter scavenging by golden eagles (Aquila chrysaetos) and bald eagles (Haliaeetus leucocephalus) in eastern Washington and Oregon, USA. Our objectives were to better understand exposure risk of individual eagles to lead contaminants and evaluate factors that affect eagle visitation to carrion to inform measures that reduce lead exposure. We studied photo sequences from 108 traps ( = 2,725 ± 306 [SE] images/trap) and used plumage and physical characteristics to track visitation of 183 individual golden eagles and 90 bald eagles at deer (Odocoileus spp.) carrion until it was totally consumed. At least 1 eagle visited 76% of traps ( = 2.5 ± 0.3 unique eagles/trap). On average, an eagle visited a trap 3.4 ± 0.2 times (range = 1–19 visits) over 1.9 ± 0.1 days (range = 1–9 days). We used general linear mixed models to identify influences on number of eagle visits and pooled visit duration. Individual golden eagles visited carrion about 25% more often and 50% longer than bald eagles, and individual juvenile eagles visited carrion more often and longer than immature and adult eagles. On average, an eagle made an additional visit to carrion for every golden eagle that came to the same trap. Eagles spent less time at offal ( = 26.2 ± 6.4 min) than at a whole carcass ( = 92.9 ± 7.5 min), and understory vegetation immediately surrounding carrion was associated with a 30% reduction in visitation time. In the Pacific Northwest during winter, adult and juvenile golden eagles, by virtue of their abundance and visitation to carrion compared to the immature age class and bald eagles of all ages, have the highest potential for exposure to anthropogenic effects from carrion visitation. Concealment of offal piles in vegetation may reduce, but not eliminate, eagle use because of competing scavengers that expose carrion locations. We found no evidence that carrion proximity to nearest known nests, topography, or snow cover affect visitation by eagles. Thus, short of using alternative ammunition to lead, we recommend burial or removal of offal from hunter-killed ungulates. © 2019 The Wildlife Society.     

Assessing Population Viability of Black Bears using Spatial Capture-Recapture Models

The Central Georgia Bear Population (CGP) is the least abundant and most isolated of Georgia's 3 American black bear (Ursus americanus) populations. Beginning in 2011, changes to regulations governing harvest of the CGP resulted in an increase in female bear harvest, creating concern that future harvest could be an important influence on population viability. Hence, our objective was to assess viability of the CGP under various levels of female mortality. During 2012–2016, we used barbed-wire hair snares to collect bear hair samples from within the range of the CGP in Georgia, USA. We used microsatellite genotyping to identify individual bears and created robust-design, spatial detection histories for all female bears detected. We fit open population spatial capture-recapture (SCR) models to the detection histories in a Bayesian framework. We used the Widely Applicable Information Criterion (WAIC) to rank models that varied with respect to sources of variation in detection probability, survival, and per capita recruitment, and used the model with the lowest WAIC to forecast dynamics of the CGP 50 years into the future under various levels of female mortality. We assessed the 50-year extinction probability under a continuation of mortality levels documented during 2012–2016, and under incremental increases in female mortality above this baseline. The top model included density-dependent per capita recruitment, annual variation in detection probability, and a trap-level behavioral response. Abundance increased from 106 (95% CI = 86–132) females in 2012 to 136 (95% CI = 113–161) females in 2013 and remained relatively stable thereafter. Annual female survival was 0.75 (95% CI = 0.69–0.82) and did not vary among years. The per capita recruitment rate decreased over time as density increased, and was 0.49 (95% CI = 0.33–0.66) during the first time interval and 0.29 (95% CI = 0.20–0.38) during the final time interval. Annual growth rate () was 1.28 (95% CI = 1.07–1.52) between 2012 and 2013 but decreased throughout the study, ending at 1.04 (95% CI = 0.93–1.17). Forecasts indicated continuation of the female mortality levels experienced from 2012–2016 were sustainable over 50 years, with the estimated extinction risk being <0.001%. Increasing annual harvest by 5 females introduced a negligible increase in the 50-year probability of extinction, but harvesting an additional 10 females/year caused extinction risk to rise to 1.15%. We recommend that harvest regulations are structured such that mortality rates remain at current levels or do not increase by more than an annual average of 5 females above levels observed during our study. Furthermore, we recommend that managers continue to monitor the population so that harvest regulations and population models can be refined over time. © 2020 The Wildlife Society.     

Effects of Midazolam on Corticosterone and Blood Gases in Spectacled Eiders Prior to Transmitter Implantation

Stress and physical exertion may affect the physiology and behavior of wildlife during and after capture, and consequently, survival following release. Such effects may reduce the quality and quantity of the data obtained from captured wildlife. We captured spectacled eiders (Somateria fischeri), a species listed as threatened under the United States Endangered Species Act, in western Alaska, USA, during spring 2018 for surgical implantation of satellite transmitters. We evaluated the efficacy of midazolam, a benzodiazepine sedative given at capture, to reduce stress and physical exertion. We dosed spectacled eiders with either midazolam (5 mg/ml, = 2.2 mg/kg intramuscular; n = 20) or saline (0.7 ml intramuscular; n = 20) at the point of capture. We assessed sedation level and collected blood samples upon arrival to the field surgery site and at anesthetic induction. We found that midazolam reduced mean corticosterone concentration by 29% and median lactate concentration by 30.3% at the mean arrival time (42 min post-dosing) relative to the control group. These effects had abated by the mean induction time (99 min post-dosing). Unexpectedly, blood pH was reduced in the midazolam treatment relative to controls at both arrival and induction, which likely resulted from sedative-induced respiratory depression that was easily treated with intubation and mechanical ventilation, and administration of the reversal drug, flumazenil. Low blood pH was not associated with negative post-surgical outcomes, as had been found in spectacled eiders with acidosis caused by anaerobic metabolism typical of physical exertion. Intramuscular injection of midazolam in the field effectively reduced stress and physical exertion in spectacled eiders prior to surgical implantation of transmitters. © 2021 The Wildlife Society.     

Nest survival and productivity of translocated and resident burrowing owls in Arizona

Development activities associated with urbanization can directly displace animals, causing high mortality and dispersal rates. Wildlife managers have attempted to mitigate the impacts of development on burrowing owls (Athene cunicularia), a species susceptible to ground-disturbing activities, by translocating them away from areas slated for development. In this study, we evaluated the effects of translocation on burrowing owl reproduction by comparing nest survival and productivity of owls involved in an ongoing translocation program in Arizona, USA, with that of resident owls. We used nest survival models to evaluate differences in nest survival and generalized linear models with Poisson error to assess differences in productivity. In 2017, cumulative nest survival (CNS) was lower among current-year translocated owls (i.e., owls translocated within the last year; CNS = 0.34, 95% CI = 0.18, 0.51) compared to non-translocated resident owls (0.83, 95% CI = 0.71, 0.94), but CNS was similar between previously translocated owls (i.e., those translocated >1 yr ago, CNS = 0.81, 95% CI = 0.64, 0.98) and residents. Likewise, in 2018, CNS was lower for current-year translocated owls (CNS = 0.12, 95% CI = 0.00, 0.24) compared to residents (CNS = 0.68, 95% CI = 0.50, 0.87) and previously translocated owls (CNS = 0.65, 95% CI = 0.40, 0.90). Productivity was significantly lower for current-year translocated owls ($\bar{x}$ = 0.5 fledglings/nest) compared to residents ($\bar{x}$ = 2.4 fledglings/nest) and previously translocated owls ($\bar{x}$ = 1.5 fledglings/nest) across sites and years. With the current methods of translocation, owls had poor reproductive success in the first year after release, but if they survived 2 years after release, they had similar nest survival and productivity compared to residents. Our results demonstrate that the current practice of releasing translocated burrowing owls in the Phoenix, Arizona area during the breeding season depresses reproduction and should be substantially changed. Nest survival was low and this was mainly attributed to nest establishment of translocated owls within release tents (acclimation structures used in translocations that involve soft release) where 85% of nests failed following tent removal. Translocation approaches that reflect a closer fit to the timing and behavior of the species should be tested to determine whether they result in better success. In particular, future studies should examine the translocation results of releasing owls as male-female pairs or single birds during the nonbreeding period.     

A tale of two populations: vital rates of fishers in British Columbia,Canada

Fishers (Pekania pennanti) are a forest-dependent carnivore of conservation concern in British Columbia, Canada. Ecological, spatial, and genetic evidence suggests that there are 2 distinct populations (Boreal and Columbian) that occur in forests at low to moderate elevations in the boreal and central interior regions of the province. In British Columbia, fishers occur at low densities relative to other parts of their range in North America, are trapped for their fur, and are sensitive to habitat change. Despite these factors, little demographic information exists to assist with management decisions for these populations. We collated and analyzed survival and reproductive data from 100 radio-tagged fishers from 5 independent studies conducted between 1990 and 2012 in British Columbia: 2 in the Boreal population, and 3 in the Columbian population. We also collated litter size data from 1 den box study and a translocation project of fishers from the Columbian population. Annual survival rates were not significantly different between the populations or between males and females; however, adult survival rates were higher than subadults (0.79 and 0.63, respectively). Subadult females had significantly lower survival rates than other sex or age classes. Reproductive rates were significantly different between the 2 populations (denning rate = 0.54 [Columbian], 0.82 [Boreal]; $\overline{x}$ litter size = 1.7 [Columbian], 2.6 [Boreal]). These differences resulted in net reproductive rates in the Columbian population that were less than half of those in the Boreal population (0.92 kits/reproductive season compared to 2.13, respectively). Population growth rates suggest that the Columbian population may have been declining during the studies, whereas the Boreal population may have been increasing (0.96 compared to 1.20). Consequently, we suggest that focused and intensive habitat and population management for fishers are needed in British Columbia to ensure population sustainability, particularly for the Columbian population.     

Sarcoptes scabiei: The Mange Mite with Mighty Effects on the Common Wombat (Vombatus ursinus)

Parasitism has both direct and indirect effects on hosts. Indirect effects (such as behavioural changes) may be common, although are often poorly described. This study examined sarcoptic mange (caused by the mite Sarcoptes scabiei) in the common wombat (Vombatus ursinus), a species that shows severe symptoms of infection and often causes mortality. Wombats showed alterations to above ground behaviours associated with mange. Infected wombats were shown to be active outside of the burrow for longer than healthy individuals. Additionally, they spent more time scratching and drinking, and less time walking as a proportion of time spent above ground when compared with healthy individuals. They did not spend a higher proportion of time feeding, but did have a slower feeding rate and were in poorer body condition. Thermal images showed that wombats with mange lost considerably more heat to the environment due to a diminished insulation layer. Infection status did not have an effect on burrow emergence time, although this was strongly dependent on maximum daily temperature. This study, through the most detailed behavioural observations of wombats to date, contributes to a broader understanding of how mange affects wombat health and abundance, and also to our understanding of the evolution of host responses to this parasite. Despite being globally dispersed and impacting over 100 species with diverse intrinsic host traits, the effects of mange on hosts are relatively poorly understood, and it is possible that similar effects of this disease are conserved in other host species. The indirect effects that we observed may extend to other pathogen types.