White-tailed Deer Odocoileus Virginianus Research Articles

Molecular Characterization of Ostertagia mossi and Ostertagia dikmansi from White-tailed Deer (Odocoileus virginianus) Confirms They Are the Same Species.

To examine whether Ostertagia mossi and Ostertagia dikmansi from white-tailed deer (Odocoileus virginianus) are separate species, we obtained DNA sequences for the cytochrome C oxidase subunit I and internal transcribed spacer 2 gene targets for phylogenetic analyses. Neither target revealed separation between morphotypes, confirming they are the same species and providing new data on Ostertagia morphotypes.

An Updated Framework for Modeling White-Tailed Deer (Odocoileus virginianus) Habitat Quality in Illinois, USA.

White-tailed deer (Odocoileus virginianus) are a cervid species found mostly in the Americas. Managing white-tailed deer requires understanding their relationship with the environment, which was characterized by Roseberry and Woolf (Wildlife Society Bulletin 1, 1998, 252) for all counties in Illinois, USA, who incorporated habitat quantity and quality in a deer habitat suitability index. However, this index was based on satellite imagery from 1996 and did not explore the smaller spatial scales used by deer. Our study addressed these gaps by developing a deer land cover utility (LCU) score for each TRS (township, range, and section), township, and county in Illinois based on the methodology outlined in Roseberry and Woolf (Wildlife Society Bulletin 1, 1998, 252) but using data from the National Land Cover Database (2001-2021). These deer LCU scores were validated against minimum deer population data using Bayesian regression with additional covariates relevant to hunting and deer density. These models performed well with Bayesian R 2 values of 0.501 (TRS), 0.5 (township), and 0.969 (county). The regression coefficients for the deer LCU scores were statistically significant (95% credibility interval not containing 0) and positive at the TRS, township, and county levels, reflecting the expected relationship between minimum deer density and deer LCU. Predictions made by these regression models on new data were accurate, with the median absolute difference between the true and predicted values being 0.398 deer/km2 for TRS', 0.085 deer/km2 for townships, and 0.066 deer/km2 for counties. This deer LCU could be used in other studies about deer in Illinois or studies in which deer are a relevant factor such as investigations about deer disease or tick distribution. This modeling approach could also be adapted to different wild species, locations, and/or time periods for which land cover data is available.

Insights into archaeological and modern neotropical biomes: Examining diet and shape variation through white-tailed deer lower third molar

The white-tailed deer (Odocoileus virginianus Zimmermann 1780) holds significant ecological importance across the Americas, both historically and in modern times. This species ranges from southern Canada to Brazil and exhibits polytypic characteristics, adapting well to diverse habitats including temperate, subtropical, semi-arid, rainforest, and savanna environments. In paleontology and archaeology, the comparison of dental characteristics between extant mammal species with known diets is commonly employed to infer the feeding behaviors of their ancient counterparts. This method assumes that extant and fossil species share similar dietary preferences, aiding in the identification of past environmental contexts. Consequently, we employed a multiproxy approach, combining the study of dental wear and 2D geometric morphometrics, to investigate potential relationships between molar shape, diet, and biomes among extant white-tailed deer populations across the Americas. Our analysis included a comparison with archaeological data from Panama. We sampled 274 extant lower second molar specimens for micro- and mesowear analysis, along with 105 lower third molar specimens from natural science museums for 2D geometric morphometric analysis. These were compared with a sample of 65 archaeological specimens from Panama. Our findings revealed distinct variations in the shape of lower m3 molars among extant white-tailed deer populations across different biomes, with notable differences observed in the archaeological samples as well. Micro- and mesowear analyses also indicated biome-related differences, suggesting a general browsing diet for white-tailed deer with nuanced variations across biomes. Mesowear analysis further suggested a dietary spectrum ranging from pure browsers to browser-mixed feeders. These findings offer valuable insights for the interpretation of fossil deer specimens recovered from archaeological sites.

Study on sentinel hosts for surveillance of future COVID-19-like outbreaks

The spread of SARS-CoV-2 to animals has the potential to evolve independently. In this study, we distinguished several sentinel animal species and genera for monitoring the re-emergence of COVID-19 or the new outbreak of COVID-19-like disease. We analyzed SARS-CoV-2 genomic data from human and nonhuman mammals in the taxonomic hierarchies of species, genus, family and order of their host. We find that SARS-CoV-2 carried by domestic dog (Canis lupus familiaris), domestic cat (Felis catus), mink (Neovison vison), and white-tailed deer (Odocoileus virginianus) cluster closely to human-origin viruses and show no differences in the majority of amino acids, but have the most positively selected sites and should be monitored to prevent the re-emergence of COVID-19 caused by novel variants of SARS-CoV-2. Viruses from the genera Panthera (especially lion (Panthera leo)), Manis and Rhinolophus differ significantly from human-origin viruses, and long-term surveillance should be undertaken to prevent the future COVID-19-like outbreaks. Investigation of the variation dynamics of sites 142, 501, 655, 681 and 950 within the S protein may be necessary to predict the novel animal SARS-CoV-2 variants.

Effective Field Sampling of Rectoanal Mucosa-Associated Lymphoid Tissue for Antemortem Chronic Wasting Disease Testing in White-tailed Deer (Odocoileus virginianus).

Chronic wasting disease (CWD) is a fatal prion disease of cervids that has spread across much of North America. Although gold standard CWD diagnostics involve postmortem testing of medial retropharyngeal lymph nodes or obex (brain stem), a key tissue sample for antemortem testing is rectoanal mucosa-associated lymphoid tissue (RAMALT). However, collection of an adequate sample (i.e., enough lymphoid follicles) may be affected by factors such as deer age, repeated sampling, skill of the sampler, and adverse conditions during collection. Here, we document the protocol used to train personnel for RAMALT collection in a large study of free-ranging white-tailed deer (Odocoileus virginianus) in Wisconsin, USA, and determine factors that contributed to the occurrence of inadequate RAMALT samples. Our training protocol included hands-on experience with postmortem tissues, as well as a mentored collection process in the field. Collection of RAMALT under field conditions was highly successful, with 763/806 (94.7%) samples deemed adequate for subsequent testing. Although inadequate samples were rare, they were more likely to occur with older deer and when samples were collected at dusk (i.e., limited ambient lighting). We conclude that RAMALT collection can be highly successful under adverse field conditions, including with technicians with limited prior veterinary experience, and we provide details of our training program to facilitate repeatability in other antemortem CWD testing efforts.

Demographic Risk Factors Vary in the Invasion Front of Chronic Wasting Disease in West Virginia, USA.

After detecting chronic wasting disease (CWD) in white-tailed deer (Odocoileus virginianus) in Hampshire County, West Virginia, USA, in 2005, we investigated the change of CWD apparent prevalence and potential factors influencing infection risk during the invasion front. Over eight sampling years (2006-2012 and 2017) during a 12-yr period within a 101-km2-area monitoring zone, we sampled and tested a total of 853 deer for CWD by ELISA and immunohistochemistry. Bayesian logistic regression of risk factors included collection year, age class, sex, and adjusted body weight (weight after accounting for sex, age, kidney fat index, and number of fetuses). In the whole-herd model (n=634), collection year, age, and adjusted body weight were associated with increased odds of CWD, whereas an age-weight interaction had a negative relationship. We found that males drove the positive associations with age and adjusted body weight, whereas females were responsible for the negative interaction effect. These findings suggest potential behavioral and physiological mechanisms related to sex that may influence CWD exposure. Older males exhibited higher CWD prevalence, aligning with previous studies. Notably, the novel finding of adjusted body weight as a risk factor in males warrants further investigation, and this study highlights the need for future research on social behavior and its role in CWD transmission within white-tailed deer populations.

Complex interactions of deer herbivory, soil chemistry, and competing vegetation explain oak–hickory forest tree regeneration in central Pennsylvania, USA

The root causes of forest tree regeneration failure are difficult to resolve, although numerous studies show ungulate herbivory, soil conditions, and competition from undesirable vegetation as likely contributors. To better understand the relative importance of each issue, we conducted a 7-year manipulative experiment to assess the interactive effects of white-tailed deer ( Odocoileus virginianus) herbivory, soil acidity, and competing vegetation on tree regeneration in oak–hickory forests of central Pennsylvania, USA. Outcomes depended on initial tree seedling abundance, and all three factors had significant interactions. At low initial seedling abundance, fencing resulted in the greatest increase, but all treatments had a positive effect on seedling growth and abundance. At higher initial seedling abundance, abundance failed to recover 7 years after herbicide treatment and soil pH was an important predictor. When soil pH was >4.6 from lime application, seedling growth and abundance in unfenced controls with high initial abundance was comparable to the fenced-only treatment. Competing vegetation, assumed to be a symptom of excessive, long-term deer herbivory, does not seem to be the primary factor limiting tree regeneration in our study area. Ameliorating acid deposition warrants greater consideration as a management action because it could provide long-lasting benefits compared to short-term fence installations.

Dear Malaria: Deer Have Malaria! Prevalence ofPlasmodium odocoilei Infection in White-tailed deer in Pennsylvania

Abstract Background To combat antimalarial treatment resistance, better understanding of malaria pathogenesis is needed, but existing animal model have various limitations. Notably, prevailing murine models require laboratory infection of non-natural host species. In 2016, the parasite Plasmodium odocoilei was identified in white-tailed deer (Odocoileus virginianus). This was the first non-human mammalian malaria parasite identified in North America, representing a novel naturally occurring model system that allows for integrated examination of host, vector, and systems parasite biology. In addition, sickle hemoglobinopathy is exceptionally common among white-tailed deer, occurring in up to 60% of apparently healthy animals. In humans, the prevalence of sickle hemoglobinopathy in individuals with ancestry from malaria-endemic regions is due to the protective effects of sickle trait against severe malaria. Thus, the white-tailed deer-P. odocoilei system represents the only known naturally occurring model of the association between malaria parasite biology and sickle cell disease. Pennsylvania white-tailed deer have not previously been surveyed for infection. In this study, we determined P. odocoilei prevalence in a sample of 170 Pennsylvania white-tailed deer. Methods We amplified the CytB gene of P. odocoilei by nested PCR from DNA extracted from homogenized white-tailed deer tongue tissue obtained from the PennVet Wildlife Futures Program. We confirmed samples screening positive on gel electrophoresis via unprimed sequencing (Plasmidsaurus, USA) and NCBI-BLAST analysis. Results We estimate the prevalence of P. odocoilei infection in Pennsylvania white-tailed deer to be 0.6% (1 of 170 samples). Sequencing of the positive sample revealed a 621-bp sequence with close sequence identity to previous North American isolates of P. odocoilei (query cover 91-100%, percent identity 99.34-100.00%). Biobank metadata showed the positive sample originated from a roadkilled yearling male picked up at GPS coordinates (40.8423, -79.0409) on August 15, 2022. Conclusion P. odocoilei is endemic to Pennsylvania white-tailed deer. Our future directions include screening of additional samples, determination of host hemoglobin allele frequencies, detailed parasite genetic studies, and entomologic studies to elucidate vector biology. In addition, granular sample metadata collected by the PennVet Wildlife Futures Program will allow us to analyze the effects of geographic, demographic, and temporal variables on epidemiology. In sum, our survey data empowers future Pennsylvania-based studies to take advantage of the only known naturally occurring animal model of sickling and its association with protozoan infection.

Measuring the benefit of a defensive trait: Vigilance and survival probability.

Defensive traits are hypothesized to benefit prey by reducing predation risk from a focal predator but come at a cost to the fitness of the prey. Variation in the expression of defensive traits is seen among individuals within the same population, and in the same individual in response to changes in the environment (i.e., phenotypically plastic responses). It is the relative magnitude of the cost and benefit of the defensive trait that underlies the defensive trait expression and its consequences to the community. However, whereas the cost has received much attention in ecological research, the benefit is seldom examined. Even in a defensive trait as extensively studied as vigilance, there are few studies of the purported benefit of the behavior, namely that vigilance enhances survival. We examined whether prey vigilance increased survival and quantified that benefit in a natural system, with white-tailed deer (Odocoileus virginianus) experiencing unmanipulated levels of predation risk from Florida panther (Puma concolor coryi). Deer that spent more time vigilant (as measured by head position using camera trap data) had a higher probability of survival. Indeed, an individual deer that was vigilant 75% of the time was more than three times as likely to be killed by panthers over the course of a year than a deer that was vigilant 95% of the time. Our results therefore show that within-population variation in the expression of a defensive trait has profound consequences for the benefit it confers. Our results provide empirical evidence supporting a long-held but seldom-tested hypothesis, that vigilance is a behavior that reduces the probability of predation and quantifies the benefit of this defensive trait. Our work furthers an understanding of the net effects of a trait on prey fitness and predator-prey interactions, within-population variation in traits, and predation risk effects.

Isotope values reveal “canopy effect” in deer territoriality and maize consumption for dogs from archaeological sites in Kentucky dating to the Middle Woodland through Late Fort Ancient time periods

This research analyzes stable carbon, nitrogen, and oxygen isotope values in tooth collagen and enamel to investigate foraging and territorial behavior in white-tailed deer (Odocoileus virginianus Zimmermann) and maize (Zea mays Linneaus) consumption in dogs (Canis familiaris Linneaus). The study analyzed 22 deer teeth from 13 archaeological sites in Kentucky covering a span of approximately 1,500 years of human occupation. The article presents evidence of foraging and territorial behavior in white-tailed deer, identified through the “canopy effect” observed in deer stable carbon isotope values in remains spanning from the Middle Woodland (200 BCE – CE 500) to Late Fort Ancient (CE 1400 – 1680) time periods in Kentucky. Additionally, teeth samples from nine dog and one wolf (Canis lupus Linneaus) were analyzed and indicate significant consumption of maize in seven of the dog samples. These specimens came from seven archaeological sites in Kentucky dating from the Early through Late Fort Ancient (CE 1400 – 1680) time periods. The study also contributes to the growing database of isotope studies in the Eastern Woodlands by presenting carbon and nitrogen isotope values on deer bone collagen from nine deer bone samples from three of the same archaeological sites dating to the Middle Woodland to Early Late Woodland.

Estimation of Contact Time Among Animals from Telemetry Data

Continuous processes in most applications are measured discretely with error. This complicates the task of detecting intersections and the number of intersections between two continuous processes (i.e., when the processes have the same value). Intersections of continuous processes are scientifically important, but challenging to estimate from data. For example, in the field of animal ecology, intersections of the paths of moving animals tracked with satellite technologies can be used to understand disease transmission. We illustrate how to quantify contact between animals using telemetry data (i.e., the recorded locations of an animal over time). We introduce our method to quantify contact time with accessible concepts from introductory stochastic process literature, such as Brownian motion. Then, we provide two data examples using white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) telemetry data in a region with high prevalence of chronic wasting disease. Our work provides a needed connection between existing model-based literature for animal movement and rule-based literature for animal interaction. Further, our work illustrates a unique statistical problem receiving minimal attention with broad applicability in human and livestock tracking.

Causes of mortality in farmed white-tailed deer in the midwestern United States, 2004-2023.

Farmed cervids are of growing economic importance in the midwestern United States. Although diseases of wild and captive cervids have been examined in more northerly climates, little information exists on the health challenges of deer in the Midwest. We characterized and summarized the causes of mortality in farmed white-tailed deer (Odocoileus virginianus) submitted to the University of Missouri Veterinary Medical Diagnostic Laboratory (Columbia, MO, USA) over a 19-y period (2004-2023). Of 388 cases examined, 253 (65%) were carcasses submitted for autopsy, and 135 (35%) cases were tissue samples harvested by field veterinarians. Infectious disease was the most common cause of mortality (n = 335; 86.3%). Of infectious causes, primary pneumonia was most common (n = 140; 41.7%), followed by septicemia (n = 68; 20.1%), and primary enteritis (n = 64; 19.1%). Viruses were detected in 18% of pneumonia cases. The most common non-infectious diagnoses were emaciation and trauma (both 4 each; 1%). Thirteen animals (3.4%) died of unknown causes. Forty-nine percent of cases were juvenile deer <1-y-old. Most cases were received in the summer (212; 54.6%). Infectious diseases, particularly bacteria and viruses, pose a significant health challenge to farmed deer in the midwestern United States.

Modeling platform to assess the effectiveness of single and integrated Ixodes scapularis tick control methods

BackgroundLyme disease continues to expand in Canada and the USA and no single intervention is likely to curb the epidemic.MethodsWe propose a platform to quantitatively assess the effectiveness of a subset of Ixodes scapularis tick management approaches. The platform allows us to assess the impact of different control treatments, conducted either individually (single interventions) or in combination (combined efforts), with varying timings and durations. Interventions include three low environmental toxicity measures in differing combinations, namely reductions in white-tailed deer (Odocoileus virginianus) populations, broadcast area-application of the entomopathogenic fungus Metarhizium anisopliae, and fipronil-based rodent-targeted bait boxes. To assess the impact of these control efforts, we calibrated a process-based mathematical model to data collected from residential properties in the town of Redding, southwestern Connecticut, where an integrated tick management program to reduce I.xodes scapularis nymphs was conducted from 2013 through 2016. We estimated parameters mechanistically for each of the three treatments, simulated multiple combinations and timings of interventions, and computed the resulting percent reduction of the nymphal peak and of the area under the phenology curve.ResultsSimulation outputs suggest that the three-treatment combination and the bait boxes–deer reduction combination had the overall highest impacts on suppressing I. scapularis nymphs. All (single or combined) interventions were more efficacious when implemented for a higher number of years. When implemented for at least 4 years, most interventions (except the single application of the entomopathogenic fungus) were predicted to strongly reduce the nymphal peak compared with the no intervention scenario. Finally, we determined the optimal period to apply the entomopathogenic fungus in residential yards, depending on the number of applications.ConclusionsComputer simulation is a powerful tool to identify the optimal deployment of individual and combined tick management approaches, which can synergistically contribute to short-to-long-term, costeffective, and sustainable control of tick-borne diseases in integrated tick management (ITM) interventions.Graphical

Range-wide salamander densities reveal a key component of terrestrial vertebrate biomass in eastern North American forests.

Characterizing the population density of species is a central interest in ecology. Eastern North America is the global hotspot for biodiversity of plethodontid salamanders, an inconspicuous component of terrestrial vertebrate communities, and among the most widespread is the eastern red-backed salamander, Plethodon cinereus. Previous work suggests population densities are high with significant geographic variation, but comparisons among locations are challenged by lack of standardization of methods and failure to accommodate imperfect detection. We present results from a large-scale research network that accounts for detection uncertainty using systematic survey protocols and robust statistical models. We analysed mark-recapture data from 18 study areas across much of the species range. Estimated salamander densities ranged from 1950 to 34 300 salamanders ha-1, with a median of 9965 salamanders ha-1. We compared these results to previous estimates for P. cinereus and other abundant terrestrial vertebrates. We demonstrate that overall the biomass of P. cinereus, a secondary consumer, is of similar or greater magnitude to widespread primary consumers such as white-tailed deer (Odocoileus virginianus) and Peromyscus mice, and two to three orders of magnitude greater than common secondary consumer species. Our results add empirical evidence that P. cinereus, and amphibians in general, are an outsized component of terrestrial vertebrate communities in temperate ecosystems.

Laparoscopic artificial insemination of white-tailed deer with fresh sex-sorted semen

This case study describes the feasibility of using chilled, sex-sorted semen for laparoscopic artificial insemination (AI) in the captive white-tailed deer (Odocoileus virginianus) industry. Ejaculates from 3 bucks were collected, extended, and shipped overnight for flow cytometric sex-sorting. Sex-sorted semen was chilled and shipped back overnight. Synchronized does were bred using chilled, sex-sorted (n = 30, farm 1; n = 10, farm 2) or conventional frozen (n = 7, farm 2) semen by laparoscopic AI. Does were subsequently turned out with bucks. Percentage of bucks born via AI with sex-sorted semen was 85% (28/33) for farm 1 and 100% (16/16) for farm 2. Percentage of bucks born by natural cover was 50% (12/24) for farm 1 and percentage of bucks born by using either conventional semen or live cover was 56% (9/14) for farm 2. This case study demonstrated acceptable results using chilled, sex-sorted semen in white-tailed deer herds as a technique to manipulate the sex proportions per breeding season.

Patterns of Hemorrhagic Disease in White-Tailed Deer (Odocoileus virginianus) in the Great Plains of the USA, 1982-2020.

Hemorrhagic disease (HD) of deer is caused by epizootic hemorrhagic disease virus (EHDV) or bluetongue virus (BTV) and is considered one of the most important viral diseases of white-tailed deer (Odocoileus virginianus). Despite evidence of changing patterns of HD in the northeastern and upper midwestern US, the historical and current patterns of HD in the Great Plains remain poorly described. We used results from an annual survey documenting HD mortality to characterize historic and current patterns of HD in the northern and central Great Plains (North Dakota, South Dakota, Nebraska, Kansas, and Oklahoma), US, between 1982 and 2020. Further, we assessed temporal change using linear regression to determine change in annual reporting intensity (percentage of counties in a state with reported HD) and change in reporting frequency (the number of years a county or state reported HD) during each decade between 1982 and 2020. Across the 38-yr study period, HD reports expanded northeast across latitude and longitude. Intensity of HD reports significantly increased during this period for three (North Dakota, South Dakota, Kansas) of five states examined. Frequency of reports also increased for all five states. Such changes in northern latitudes might lead to increased deer mortality in regions where HD epizootics have been historically less frequent. Understanding how patterns of HD are changing on the landscape is important when considering future deer management in the face of other mortality factors.

Activity responses of a mammal community to a 17-year cicada emergence event

Abstract During a limited period in the summer of 2021, 17-year cicada species (Magicicada cassini, M. septendecula, M. septendecim) represented a large pulse of easily accessible food unique to forest ecosystems in the eastern United States. Using trail cameras and acoustic recorders, we tested whether the activity levels of 8 mammal species in northwestern Indiana shifted in response to spatial and temporal variation in cicada densities from 18 May to 20 June 2021. Cicada densities varied temporally and spatially across all study sites. Most mammal species with sufficient data showed no response to cicada emergence, including 2 tree squirrel species, Peromyscus mice, Eastern Chipmunks (Tamias striatus), and 2 species of bats. Raccoons (Procyon lotor), likely cicada predators, showed a quadratic or more complex activity response to cicada abundance, indicating a potential saturation point at densities near 1 cicada per m2. Surprisingly, White-tailed Deer (Odocoileus virginianus) activity decreased to almost 0 at the same cicada densities when we expected no change in activity. While size or accessibility may exclude cicadas as prey for small and volant mammals, our results suggest predation and satiation by Raccoons. In contrast, deer may be avoiding areas of cicada abundance due to other stimuli, such as high noise output, which may decrease their ability to detect predators.

Estimating encounter-habitat relationships with scale-integrated resource selection functions.

Encounters between animals occur when animals are close in space and time. Encounters are important in many ecological processes including sociality, predation and disease transmission. Despite this, there is little theory regarding the spatial distribution of encounters and no formal framework to relate environmental characteristics to encounters. The probability of encounter could be estimated with resource selection functions (RSFs) by comparing locations where encounters occurred to available locations where they may have occurred, but this estimate is complicated by the hierarchical nature of habitat selection. We developed a method to relate resources to the relative probability of encounter based on a scale-integrated habitat selection framework. This framework integrates habitat selection at multiple scales to obtain an appropriate estimate of availability for encounters. Using this approach, we related encounter probabilities to landscape resources. The RSFs describe habitat associations at four scales, home ranges within the study area, areas of overlap within home ranges, locations within areas of overlap, and encounters compared to other locations, which can be combined into a single scale-integrated RSF. We apply this method to intraspecific encounter data from two species: white-tailed deer (Odocoileus virginianus) and elk (Cervus elaphus) and interspecific encounter data from a two-species system of caribou (Rangifer tarandus) and coyote (Canis latrans). Our method produced scale-integrated RSFs that represented the relative probability of encounter. The predicted spatial distribution of encounters obtained based on this scale-integrated approach produced distributions that more accurately predicted novel encounters than a naïve approach or any individual scale alone. Our results highlight the importance of accounting for the conditional nature of habitat selection in estimating the habitat associations of animal encounters as opposed to 'naïve' comparisons of encounter locations with general availability. This method has direct relevance for testing hypotheses about the relationship between habitat and social or predator-prey behaviour and generating spatial predictions of encounters. Such spatial predictions may be vital for understanding the distribution of encounters driving disease transmission, predation rates and other population and community-level processes.

Effect of Herbivory on the Nutritional Value of Six Hardwood Species for White-Tailed Deer in the Allegheny Forest

Abstract Herbivores alter plant quantity and quality through direct tissue consumption and indirectly via the structural and chemical allocational strategies plants deploy in response to herbivory. Herein, we examine how browsing by white-tailed deer Odocoileus virginianus alters nutritional quality of six regenerating hardwood species: red maple Acer rubrum, black cherry Prunus serotina, birch Betula spp., pin cherry Prunus pennsylvanica, white ash Fraxinus americana, and American beech Fagus grandifolia. Using an established, large-scale experiment that manipulated deer access to fenced plots, we tested whether browsing altered the nutritional quality and biomass as well as nutritional capacity to support deer of six hardwood species in an early successional hardwood forest of Pennsylvania, USA. Pin cherry was the most nutritious of the six species, with greater dry matter digestibility and digestible protein and lesser neutral detergent fiber. Areas exposed to browsing had less browse biomass of stems and leaves yet greater digestible protein, an effect driven by digestible protein of pin cherry. We found no effect of browsing on neutral detergent fiber or dry matter digestibility. Although deer browsing reduced biomass of the six hardwood species, it did not alter the nutritional capacity to support lactating females in the summer. Our results confirm that browsing limits tree regeneration and available browse and provides conservative conclusions on how deer can alter their diet quality.

Predicting chronic wasting disease in white-tailed deer at the county scale using machine learning

Continued spread of chronic wasting disease (CWD) through wild cervid herds negatively impacts populations, erodes wildlife conservation, drains resource dollars, and challenges wildlife management agencies. Risk factors for CWD have been investigated at state scales, but a regional model to predict locations of new infections can guide increasingly efficient surveillance efforts. We predicted CWD incidence by county using CWD surveillance data depicting white-tailed deer (Odocoileus virginianus) in 16 eastern and midwestern US states. We predicted the binary outcome of CWD-status using four machine learning models, utilized five-fold cross-validation and grid search to pinpoint the best model, then compared model predictions against the subsequent year of surveillance data. Cross validation revealed that the Light Boosting Gradient model was the most reliable predictor given the regional data. The predictive model could be helpful for surveillance planning. Predictions of false positives emphasize areas that warrant targeted CWD surveillance because of similar conditions with counties known to harbor CWD. However, disagreements in positives and negatives between the CWD Prediction Web App predictions and the on-the-ground surveillance data one year later underscore the need for state wildlife agency professionals to use a layered modeling approach to ensure robust surveillance planning. The CWD Prediction Web App is at https://cwd-predict.streamlit.app/.