White-tailed Deer Research Articles

Facts about Wildlife Diseases: Warts in White-tailed deer (Cutaneous Fibromas).

Deer warts, or cutaneous fibromas, are skin tumors caused by papillomavirus infection that affect white-tailed deer and other deer. These growths are generally benign, but in rare cases may proliferate and impede functions like sight, movement, or feeding. Deer immune systems usually eradicate the infection over time. Found exclusively on the skin, usually around the eyes, neck, face, and forelegs, warts may be diverse in appearance and size, ranging from small fleshy nodules to larger, pendulous masses or clusters. Transmission mechanisms are suspected to involve skin contact or possibly insect vectors but remain unclear. Diagnosis is by visual examination and histopathological analysis of the wart tissue. Wild deer populations usually do not require treatment, but surgical removal is an option for captive herds. Vaccine development remains plausible but has not yet been pursued extensively.

Variation in white‐tailed and mule deer dental metrics is associated with precipitation gradients in the Americas

AbstractInvestigating the relationship between the physical environment and organismal adaptation is crucial to understanding the selective pressures that drive mammalian evolution. Of the varied approaches to exploring this relationship, macroscopic tooth wear analyses have become widely used due to their economic and simple methodologies. However, more work is needed to understand how assessments of wear patterns operate within finer levels of dietary and environmental contexts. It is specifically unclear if and how tooth wear differs inter‐ and intraspecifically between geographically widespread, large‐bodied mammalian populations. This project characterizes molar hypsodonty indices and mesowear scores of white‐tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) populations across North and Central America, investigating if and how molar wear and morphology vary over the deer's large and ecologically variable geographic distribution. While mesowear scores generally do not strongly track environmental signals within and between Odocoileus species, hypsodonty indices reveal a strong correlation between crown height and aridity, which likely represents an adaptive response to abrasive diets in areas with low precipitation.

Cryo-EM structure of a natural prion: chronic wasting disease fibrils from deer

Chronic wasting disease (CWD) is a widely distributed prion disease of cervids with implications for wildlife conservation and also for human and livestock health. The structures of infectious prions that cause CWD and other natural prion diseases of mammalian hosts have been poorly understood. Here we report a 2.8 Å resolution cryogenic electron microscopy-based structure of CWD prion fibrils from the brain of a naturally infected white-tailed deer expressing the most common wild-type PrP sequence. Like recently solved rodent-adapted scrapie prion fibrils, our atomic model of CWD fibrils contains single stacks of PrP molecules forming parallel in-register intermolecular β-sheets and intervening loops comprising major N- and C-terminal lobes within the fibril cross-section. However, CWD fibrils from a natural cervid host differ markedly from the rodent structures in many other features, including a ~ 180° twist in the relative orientation of the lobes. This CWD structure suggests mechanisms underlying the apparent CWD transmission barrier to humans and should facilitate more rational approaches to the development of CWD vaccines and therapeutics.

Enhanced detection of chronic wasting disease in muscle tissue harvested from infected white-tailed deer employing combined prion amplification assays.

Zoonotic transmission of bovine spongiform encephalopathy or mad cow disease, by presumed consumption of infected beef, has increased awareness of the public health risk associated with prion diseases. Chronic wasting disease (CWD) affects moose, elk, and deer, all of which are frequently consumed by humans. Clear evidence of CWD transmission to humans has not been demonstrated, yet, establishing whether CWD prions are present in muscle tissue preferentially consumed by humans is of increasing interest. Conventional assays including immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA) lack the sensitivity to detect low concentrations of prions presumed to be present outside neural or lymphatic tissues. Here we combined two prion amplification assays, the product of protein misfolding cyclic amplification (PMCA) applied directly into real-time quaking induced conversion (RT-QuIC) [denoted now as PQ] to demonstrate the presence of prion seeding activity (i.e. prions) in ~55% of hamstring muscles harvested from CWD-positive white-tailed deer. This compares to prion detection in only 10% of the same samples employing standard RT-QuIC. To determine the extent of CWD dissemination within muscle tissues commonly consumed we tested 7 additional muscles from a subset of deer by PQ. Tongue demonstrated the highest level of prions with ~92% positive. All negative controls remained negative in all PMCA and RT-QuIC assays. We conclude that the combination of PMCA with RT-QuIC readout permits detection of low prion concentrations present in muscle tissue of CWD-infected deer. These findings further demonstrate the utility of amplification assays as tools to detect very low levels of prion burden and supports their use to fill knowledge gaps in our understanding of CWD pathogenesis and zoonotic potential.

Spatiotemporal responses of ungulates to hunting in a fenced multi-use area

Context Human activities, such as tourism and hunting, affect the spatiotemporal behaviour of wildlife. For example, it is well documented that ungulates change their spatiotemporal behaviour as a response to hunting pressure, but less is known about ungulate responses to hunting in areas where human activity is common throughout the year and ungulates are constrained by fences. Aims In this camera-trap study, we analysed the change in spatiotemporal behaviour of wild ungulates (elk, Cervus canadensis (3519 events), moose, Alces alces (1153 events), and white-tailed deer, Odocoileus virginianus (2708 events)) in response to the hunting period in a recreational and fenced park, the Cooking Lake–Blackfoot Provincial Area, Canada. Methods We used general linear models to compare species-specific patterns of intensity of use, calculated as events per week, in response to changes in the nature of human disturbance, namely a shift from recreation to hunting activity. In particular, we compared intensity of use in and out of the hunting season to determine whether species engaged in spatial patterns of avoidance with respect to hunting. We used daily and seasonal patterns of activity to determine how ungulates shifted their temporal use in response to hunting activity and whether they became more nocturnal as a result. Key results We found that ungulates responded temporally to the hunting period by generally shifting their activity to more nocturnal hours, with white-tailed deer showing the biggest temporal shift, suggesting that the ungulates distinguish between consumptive and non-consumptive human activities. Nevertheless, temporal overlap between humans and all ungulate species increased during the hunting period as humans targeted times of increased ungulate activity. Spatially, the response was less distinctive and was species-specific. Elk showed little change in spatial behaviour in response to the hunting period. In contrast, moose decreased the use of trail areas and other areas frequented by humans, whereas deer, counterintuitively, increased the use of trail areas, albeit their use became much more nocturnal. Conclusions We have shown that responses of ungulates to hunting exceed those to non-consumptive recreational use, and whereas temporal responses (increased nocturnality) were consistent across ungulate species, spatial responses were species-specific. Implications Management in small fenced multi-use areas needs to account for shifts in the intensity of disturbance resulting from a change in human disturbance from recreational activity to hunting. Providing spatial opportunities for avoidance of humans is key for most species if hours of operation in these areas already limit the timing of human activity.

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.

Inter-laboratory comparison of real-time quaking-induced conversion (RT-QuIC) for the detection of chronic wasting disease prions in white-tailed deer retropharyngeal lymph nodes.

The rapid geographic spread of chronic wasting disease (CWD) in white-tailed deer (WTD; Odocoileus virginianus) increases the need for the development and validation of new detection tests. Real-time quaking-induced conversion (RT-QuIC) has emerged as a sensitive tool for CWD prion detection, but federal approval in the United States has been challenged by practical constraints on validation and uncertainty surrounding RT-QuIC robustness between laboratories. To evaluate the effect of inter-laboratory variation on CWD prion detection using RT-QuIC, we conducted a multi-institution comparison on a shared anonymized sample set. We hypothesized that RT-QuIC can accurately and reliably detect the prions that cause CWD in postmortem samples from medial retropharyngeal lymph node (RPLN) tissue despite variation in laboratory protocols. Laboratories from 6 U.S. states (Michigan, Minnesota, Missouri, New York, Pennsylvania, Wisconsin) were enlisted to compare the use of RT-QuIC in determining CWD prion status (positive or negative) among 50 anonymized RPLNs of known prion status. Our sample set included animals of 3 codon 96 WTD genotypes known to affect CWD progression and detection (G96G, G96S, S96S). All 6 laboratories successfully identified the true disease status consistently for all 3 tested codon 96 genotypes. Our results indicate that RT-QuIC is a suitable test for the detection of CWD prions in RPLN tissues in several genotypes of WTD.

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.

One Health collaboration is more effective than single-sector actions at mitigating SARS-CoV-2 in deer

One Health aims to achieve optimal health outcomes for people, animals, plants, and shared environments. We describe a multisector effort to understand and mitigate SARS-CoV-2 transmission risk to humans via the spread among and between captive and wild white-tailed deer. We first framed a One Health problem with three governance sectors that manage captive deer, wild deer populations, and public health. The problem framing included identifying fundamental objectives, causal chains for transmission, and management actions. We then developed a dynamic model that linked deer herds and simulated SARS-CoV-2. Next, we evaluated management alternatives for their ability to reduce SARS-CoV-2 spread in white-tailed deer. We found that single-sector alternatives reduced transmission, but that the best-performing alternative required collaborative actions among wildlife management, agricultural management, and public health agencies. Here, we show quantitative support that One Health actions outperform single-sector responses, but may depend on coordination to track changes in this evolving system.

Relative Fluctuating Asymmetry and Predictive Metrics of Cast Antler Pairs in White-Tailed Deer (Odocoileus virginianus)

Relative Fluctuating Asymmetry and Predictive Metrics of Cast Antler Pairs in White-Tailed Deer (Odocoileus virginianus)

Using Unmanned Aerial Vehicles Equipped with Thermal Cameras to Survey a Known Population of White-Tailed Deer

Abstract New technologies are emerging that may have potential for yielding more reliable population estimates for white-tailed deer Odocoileus virginianus than traditional manned aerial surveys. In a study conducted in a 116.55-ha enclosure in the Edwards Plateau ecoregion of Texas, USA, we tested the accuracy and precision of population counts by using an unmanned aerial vehicle equipped with a dual thermal–red green blue (heat detection and color video) camera to conduct a complete area count of a known, closed population of white-tailed deer. We flew surveys during 2–4 December 2019 in preprogrammed transects and replicated them three times, in both the morning and afternoon. Detection was higher during morning surveys, when we detected almost all deer that were present, compared with afternoon surveys. The accuracy and precision of morning surveys reported herein justify further research into the development of a method using this equipment for surveying large mammal populations in certain habitats.

Testing secondary sex ratio bias hypotheses in white-tailed deer in Mississippi, USA.

Natural selection favors individuals with the highest inclusive fitness (i.e., total number of descendants). In cases where one sex is more productive, one or both parents may maximize their inclusive fitness by investing in the offspring of the more prolific sex. Such preferential production can lead to skewed sex ratios at various life history stages, including at birth, resulting in secondary sex ratio bias. Several competing hypotheses have been proposed to explain observed variation in secondary sex ratios including Fisher's frequency dependence and two hypotheses related to maternal condition: Trivers-Willard and the local resource hypotheses. Although it has been shown that maternal condition can influence the number of offspring produced in white-tailed deer, there is no consensus as to which of the hypotheses drives sex ratio bias in wild populations. Using a spatiotemporally extensive dataset of pregnant white-tailed deer from Mississippi, USA, we examined fetal sex ratio in relation to the Fisherian frequency-dependence hypothesis and hypotheses related to maternal condition. While there was a male-sex ratio bias in pregnant females that reduced in intensity with the number of offspring, there was no support for condition-related hypotheses. Instead, secondary sex ratios for white-tailed deer in Mississippi were nearly consistent with Fisherian frequency dependence. Our findings add to the body of literature on secondary sex biases in white-tailed deer and help inform sex bias ratios for a southern population of a cervid of management importance in the US.

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.

Occurrence of Fox Squirrels Influenced by Fine-Scale Landscape Characteristics on a College Campus.

Urbanization and urban sprawl generally degrade and diminish wildlife habitat, threatening to extirpate local populations. However, certain synanthropic species (e.g., coyotes, white-tailed deer, and squirrels) are able to persist in urban environments and may even occur at greater densities than they do in their natural habitats. Eastern fox squirrels (Sciurus niger) are large tree squirrels that are known to be present in greater densities within urban areas. To determine how landscape characteristics may affect fox squirrel presence, we conducted line-transect surveys along sidewalks on the Texas A&M University-College Station campus to record presence of fox squirrels and nearest tree species. We calculated Jacobs' index of selectivity (D) for use of trees by fox squirrels along the transects. Squirrel density was calculated for all transects and modeled using linear regression with environmental (e.g., tree density) and survey (e.g., transect distance) variables. Fox squirrels preferred only a small number of the available tree species, primarily Quercus and Ulmus species. Observed fox squirrel density significantly increased with time of day, temperature, density of oaks (Quercus spp.), and density of all trees, and decreased with distance and area of the transect. These results suggest that even when urban areas contain suitable habitat, use of urban environments by wildlife is still highly selective and dependent on specific habitat requirements.

Temporal Characterization of Prion Shedding in Secreta of White-Tailed Deer in Longitudinal Study of Chronic Wasting Disease, United States.

Chronic wasting disease (CWD) affects cervids in North America, Asia, and Scandinavia. CWD is unique in its efficient spread, partially because of contact with infectious prions shed in secreta. To assess temporal profiles of CWD prion shedding, we collected saliva, urine, and feces from white-tailed deer for 66 months after exposure to low oral doses of CWD-positive brain tissue or saliva. We analyzed prion seeding activity by using modified amyloid amplification assays incorporating iron oxide bead extraction, which improved CWD detection and reduced false positives. CWD prions were detected in feces, urine, and saliva as early as 6 months postinfection. More frequent and consistent shedding was observed in deer homozygous for glycine at prion protein gene codon 96 than in deer expressing alternate genotypes. Our findings demonstrate that improved amplification methods can be used to identify early antemortem CWD prion shedding, which might aid in disease surveillance of cervids.

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.

Phenotypic characteristics of successful parental pairs in white-tailed deer: evidence of non-random mating

Phenotypic characteristics of successful parental pairs in white-tailed deer: evidence of non-random mating