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Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi) in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ). Mule deer were captured from 2010-2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ = 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.

Quantification of basic demographic parameters such as survival rates and cause-specific mortality is important for effective species management. We conducted a 4-year study (during May 2005-June 2009) of elk Cervus canadensis calf survival and cause-specific mortality in Pennsylvania, USA. We captured and radio-collared 93 elk calves ≤ 7 days old and monitored them weekly to detect mortality and cause of death. Of the 93 radio-collared elk calves, 15 (16%) died during our study. Despite high black bear Ursus americanus and coyote Canis latrans densities, none of the mortalities were the result of predation. Causes of death included poaching (N = 3), legal harvest (N = 2), road kill (N = 2), pneumonia (N = 1) and rumen acidosis (N = 1). We were unable to determine the cause of mortality for six of the elk calves; however, predation was eliminated as a possible source of mortality in all unknown cases. Survival probabilities were similar between sexes and among years. Summer survival (birth-31 October) was 0.92 (SE = 0.03, N = 93) and winter survival (1 November - 1 April) was 0.90 (SE = 0.04, N = 79). Annual estimated elk calf survival was 0.82 (SE = 0.04, N = 93). Our findings suggest that Pennsylvania elk calves have a > 80% chance of survival to one-year of age, despite high densities of predators known to influence elk calf survival elsewhere. The high calf survival rates that we observed indicate the availability of high quality habitat leading to excellent physical condition of elk.

Mammalian carnivores are the primary hosts for the rabies virus in terrestrial disease cycles. While rabies prevalence in Vulpes spp. and Urocyon spp. (foxes), Mephitis mephitis (Striped Skunk), and Procyon lotor (Raccoon) is well documented in Pennsylvania, the reintroduction of Martes pennanti (Fisher) provides another potential vector of this disease. We used a direct, rapid immunohistochemical test to examine brain material from 46 free-ranging Fishers collected throughout Pennsylvania from 2002–2008. Five Fishers had brain material unsuitable for rabies testing, forty Fishers tested negative for the disease, and one individual tested positive. The individual that tested positive was an adult male that was found to be positive for the Eastern Raccoon strain of rabies. This individual was trapped and radio-collared in July 2006 as part of a research project examining Fisher resource selection. Researchers monitored this individual weekly starting July 2006 until October 2006, when it was found dead beneath a brush pile. As Fisher populations continue to expand throughout portions of the northeastern United States, their potential as a vector of rabies should not be overlooked.

Chronic wasting disease (CWD) is an infectious transmissible spongiform encephalopathy that naturally affects white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi). High CWD prevalence in southeastern Wyoming appeared to contribute to local mule deer population declines during the last decade. Our objectives were to; 1) investigate the contribution of CWD to the population decline by determining the impact of disease on vital rates and estimating the population growth rate (λ) using CWD incidence, survival, and recruitment metrics; 2) identify modifications to behavior mediated by CWD by estimating home range size, distance traveled, and activity levels of infected and uninfected deer; and 3) determine CWD susceptibility of different prion protein genotyped (Prnp) deer by calculating Prnp-specific CWD incidence and use these parameters to develop a stochastic simulation model to predict population trends and genetic frequencies during the next 100 years. We captured deer using helicopter net-gun on winter range along the LaPrele Valley, southwest of Douglas, Wyoming from 2010-2014. Adult female and male deer were tonsil biopsied to test for CWD, females were tested for pregnancy using blood samples, all deer were genotyped at codon 225 within the Prnp gene, and deer were marked with global positioning system (GPS) radio-collars equipped with a mortality sensor that was activated after 4 hours of immobility. Marked deer were monitored at least twice weekly during the study and mortalities were investigated to determine cause of death. Deer were recaptured annually to retest previously uninfected deer for CWD and females for pregnancy status. During the study, 143 mule deer (118 females and 25 males) were captured and average annual CWD prevalence ranged from 21-27%. Average annual female CWD incidence was 0.26 and 0.45 for males. An extended Cox proportional hazards model revealed CWD-positive deer were over three times more likely to die during our study compared to CWD-negative deer and males were twice as likely to die compared to females. Kaplan-Meier annual survival estimates were significantly ( 2 = 40.10, p < 0.01) different between CWD-negative (0.76, SE = 0.04) and CWD-positive deer (0.32, SE = 0.06). Mean annual pregnancy (CWD-negative = 0.99, SD = 0.11; CWD-positive = 0.94, SD = 0.24) and fawn recruitment (CWD-negative = 0.48, SD = 0.65; CWD-positive = 0.56, SD = 0.65) was similar between CWD-negative and CWD-positive females with no effect of age, body condition, Prnp genotype, and observation year on these vital rates using a repeated measures analysis. Using a pre-breeding, age- and CWD-structured, female-only Leslie matrix model, we estimated λ 1 = 0.81, corresponding to a 19% annual decline in the population. When CWD was removed from our matrix, λ1 = 1.00 suggesting the population would be stable in the absence of CWD. These findings suggested the effect of CWD on adult survival was important in shaping population growth rates and CWD contributed to the observed mule deer population decline. Behavior of mule deer was also affected by CWD but differently for males and females. Home range size, estimated using local nearest-neighbor convex-hull (LoCoH) methods, was smaller for CWD-positive deer compared to CWD-negative deer except for females on summer range, but all comparisons were not statistically significant except when considering resident females. Non-migratory females that were CWD-positive had significantly smaller home ranges (3.53 km2) compared to CWD-negative females (5.25 km2). Weekly distances traveled and net displacement of CWD-positive deer were consistently shorter compared to CWD-negative deer for both males and females, but these differences were not statistically significant. Mean 24-hour activity levels were mediated by sex and season, but not by CWD status using a linear mixed effects analysis. No clear trends in activity between CWD-negative and CWD-positive females were observed, but higher peaks in activity of CWD-positive males during spring, summer, and winter were observed. Similar activity levels were observed among males regardless of CWD status during fall. These results suggested differences observed in male activity based on CWD status, but not observed in females could potentially explain higher CWD prevalence in males (average during the study = 43%) compared to females (18%). Greater activity in CWD-positive males was not associated with increased travel; rather CWD-positive males may have been more active prior to infection making them more at risk of encountering infected deer and contaminated environments. We calculated the percent overlap of CWD-negative deer home ranges with known CWD-positive deer, but did not find an association between increased home range overlap and CWD infection likely due to coarse-scale analysis, unknown CWD-positive deer in the area, and evidence that home range overlap is not a good proxy for contact among deer. Altered behavior of CWD-positive deer potentially explained higher probability of infected deer killed by mountain lions and hunters in our study. We documented 97 mortalities and mountain lion predation was the number one cause of natural mortality followed by clinical CWD. Lastly, we found that mule deer that had at least one phenylalanine (F) at codon 225 in the Prnp gene had reduced incidence of CWD (0.02, SE = 0.06) compared to homozygous serine (S) deer (0.49, SE = 0.05). Incorporation of genotype-specific CWD incidence in our spreadsheet models dramatically changed the predicted outcome, with the population remaining stable (λ1 = 1.00) with genetic-specific vital rates compared to population extirpation within 50 years when genetic-specific information was excluded. Our models with genotype-specific CWD incidence predicted a dramatic decline in the population with only 10% of the original population size remaining, but with the remnant population composed mostly of less susceptible 225FF mule deer. The non-disease-associated fitness characteristics of mule deer based on their Prnp genotypes is not known and could potentially influence the sustainability of a remnant 225FF mule deer population. While natural selection in favor of these less susceptible genotyped mule deer appears probable under the current CWD conditions, further investigations regarding the influence of CWD on observed changes in Prnp frequencies in the population are warranted.

Estimating habitat and spatial associations for wildlife is common across ecological studies and it is well known that individual traits can drive population dynamics and vice versa. Thus, it is commonly assumed that individual‐ and population‐level data should represent the same underlying processes, but few studies have directly compared contemporaneous data representing these different perspectives. We evaluated the circumstances under which data collected from Lagrangian (individual‐level) and Eulerian (population‐level) perspectives could yield comparable inference to understand how scalable information is from the individual to the population. We used Global Positioning System (GPS) collar (Lagrangian) and camera trap (Eulerian) data for seven species collected simultaneously in eastern Washington (2018–2020) to compare inferences made from different survey perspectives. We fit the respective data streams to resource selection functions (RSFs) and occupancy models and compared estimated habitat‐ and space‐use patterns for each species. Although previous studies have considered whether individual‐ and population‐level data generated comparable information, ours is the first to make this comparison for multiple species simultaneously and to specifically ask whether inferences from the two perspectives differed depending on the focal species. We found general agreement between the predicted spatial distributions for most paired analyses, although specific habitat relationships differed. We hypothesize the discrepancies arose due to differences in statistical power associated with camera and GPS‐collar sampling, as well as spatial mismatches in the data. Our research suggests data collected from individual‐based sampling methods can capture coarse population‐wide patterns for a diversity of species, but results differ when interpreting specific wildlife‐habitat relationships.