Deer Mortality Research Articles

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.

White-tailed deer population dynamics in a multipredator landscape shaped by humans.

Large terrestrial mammals increasingly rely on human-modified landscapes as anthropogenic footprints expand. Land management activities such as timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources and predation risk via changes in habitat, but these effects are not well understood in regions with diverse and changing predator guilds. In northeastern Washington state, USA, white-tailed deer (Odocoileus virginianus) are vulnerable to multiple carnivores, including recently returned gray wolves (Canis lupus), within a highly human-modified landscape. To understand the factors governing predator-prey dynamics in a human context, we radio-collared 280 white-tailed deer, 33 bobcats (Lynx rufus), 50 cougars (Puma concolor), 28 coyotes (C. latrans), and 14 wolves between 2016 and 2021. We first estimated deer vital rates and used a stage-structured matrix model to estimate their population growth rate. During the study, we observed a stable to declining deer population (lambda = 0.97, 95% confidence interval: 0.88, 1.05), with 74% of Monte Carlo simulations indicating population decrease and 26% of simulations indicating population increase. We then fit Cox proportional hazard models to evaluate how predator exposure, use of human-modified landscapes, and winter severity influenced deer survival and used these relationships to evaluate impacts on overall population growth. We found that the population growth rate was dually influenced by a negative direct effect of apex predators and a positive effect of timber harvest and agricultural areas. Cougars had a stronger effect on deer population dynamics than wolves, and mesopredators had little influence on the deer population growth rate. Areas of recent timber harvest had 55% more forage biomass than older forests, but horizontal visibility did not differ, suggesting that timber harvest did not influence predation risk. Although proximity to roads did not affect the overall population growth rate, vehicle collisions caused a substantial proportion of deer mortalities, and reducing these collisions could be a win-win for deer and humans. The influence of apex predators and forage indicates a dual limitation by top-down and bottom-up factors in this highly human-modified system, suggesting that a reduction in apex predators would intensify density-dependent regulation of the deer population owing to limited forage availability.

Mule deer mortality in the northern Great Plains in a landscape altered by oil and natural gas extraction

AbstractA worldwide increasing demand for renewable and non‐renewable energy resources has been ongoing since the mid‐1970s and is projected to increase for the next 2 decades. The effects of oil and natural gas development on wildlife mortality risk may play an important role in mule deer (Odocoileus hemionus) population dynamics. We evaluated the potential effects of oil and natural gas development on mortality risk of mule deer in western North Dakota and eastern Montana, USA. We assessed adult and juvenile female mule deer mortality risk with Poisson point process models using 265 deer fitted with global positioning system (GPS) radio‐collars that were deployed from 2013–2016. Mortality covariates included proportion of area disturbed by oil and natural gas development, distance to oil and natural gas development, distance to roads, temperature, snow depth, normalized difference vegetation index (NDVI), and age of deer. During the study there was no effect of oil and natural gas development or roads on mule deer mortality, though <1% of all deer locations were within 500 m of active drilling rigs. Mule deer mortality was greatest in winter and spring, and positively related to temperature during these seasons. Estimated annual adult survival probability was 0.79 (95% CI = 0.71–0.85). Given the strong influence of season and temperature variables on mortality risk, weather had the strongest influence on mule deer mortality during this study. Although we did not detect an effect of energy development on mule deer mortality, effects on space use resulting from development could influence deer dynamics in the region through displacement and could occur over longer time scales than we evaluated. This study can be used in pre‐development planning in a risk assessment framework to minimize effects of development on mule deer.

Moose and white‐tailed deer mortality peaks in fall and late winter

AbstractThe Grand Portage Band of Lake Superior Chippewa manages for sustainable subsistence harvests of moose (mooz; Alces alces) and white‐tailed deer (waawaashkeshi; Odocoileus virginianus). Moose populations in northern Minnesota, USA, are declining, which may necessitate alterations to Indigenous subsistence practices. Moose and deer exhibit seasonal behaviors such as altered space use and movement strategies, to which gray wolves (ma'iingan; Canis lupus) and humans may adapt, resulting in seasonal mortality patterns. Identifying periods of increased moose and deer vulnerability is important for achieving tribal conservation objectives. We assessed seasonal cause‐specific mortality of adult moose (2010–2021) and deer (2016–2022) fitted with global positioning system collars on and near the Grand Portage Indian Reservation (Gichi Onigaming; GPIR) in Minnesota and hypothesized mortality risk would be influenced by species‐specific space use patterns and weather. We estimated survival rates and mortality risk using time‐to‐event models. We recorded 42 moose mortalities (17 health issues, 8 predations, 4 subsistence harvests, 13 unknown causes) and 49 deer mortalities (26 predations, 13 harvests, 4 other causes, 6 unknown causes). Mean annual moose survival was 83.2%, and mortality risk peaked during late winter (~25 April) and fall (~8 October). Mean annual deer survival was 48.0%, and mortality risk peaked during late winter (~25 March) and during their fall migration period (~11 November). Mortality timing coincided with transitions between space use states (i.e., periods of spatial stability), suggesting ungulates are at greater risk during these transitional periods, though movement strategy (i.e., resident vs. migratory) did not influence mortality risk. Further, increased winter severity corresponded with increased deer mortality. We observed similar temporal peaks in mortality risk when harvest mortalities were censored, suggesting our observed seasonal mortality peaks occur naturally despite harvest comprising most fall deer mortality. Our results can inform population models and harvest regulations by identifying periods of mortality risk on GPIR under Anishinaabe principles of seventh‐generation conservation planning.

Ungulate-vehicle crashes peak a month earlier than 38 years ago due to global warming

Global change has manifested itself as climate warming in Central Europe in recent decades. Average daily air temperatures increased by an average of 2 °C between 1982 and 2018. Air temperature changes have affected the timing of the vegetation periods (phenophases) and have also influenced the behaviour of animals. We worked with data on wildlife-vehicle crashes (WVC) recorded by the Czech Police in the period 1982–2019. Three peaks can usually be observed (spring, summer, and autumn) in the WVC time series. Eighty percent of these records involved roe deer (Capreolus capreolus). Such a high ratio allowed us to assume that any significant changes detected in WVC will be predominantly related to roe deer. We discovered that roe deer mortality on roads occurs earlier at present in the spring than in the past. The spring peak has shifted almost a month to the beginning of the year compared to the situation 38 years ago. The changes in the respective summer and autumn peaks were not statistically significant. The results suggest the effect of climate change on roe deer behaviour through increasing air temperatures and shifting vegetation phenophases. Thus, an earlier onset of deer activity associated with territory delineation and expected higher movement activity can be indirectly determined by the analysis of the WVC time series. The observed shift in the spring WVC peak in the roe deer model reveals a shift in ungulate behavioural patterns that is not evident from other biological data and thus surprisingly offers a suitable study framework for determining the impacts of environmental change on animals.

The Impact of Variation in the Toll-like Receptor 3 Gene on Epizootic Hemorrhagic Disease in Illinois Wild White-Tailed Deer (Odocoileus virginianus).

Epizootic hemorrhagic disease (EHD) leads to high mortality in white-tailed deer (Odocoileus virginianus) and is caused by a double-stranded RNA (dsRNA) virus. Toll-like receptor 3 (TLR3) plays a role in host immune detection and response to dsRNA viruses. We, therefore, examined the role of genetic variation within the TLR3 gene in EHD among 84 Illinois wild white-tailed deer (26 EHD-positive deer and 58 EHD-negative controls). The entire coding region of the TLR3 gene was sequenced: 2715 base pairs encoding 904 amino acids. We identified 85 haplotypes with 77 single nucleotide polymorphisms (SNPs), of which 45 were synonymous mutations and 32 were non-synonymous. Two non-synonymous SNPs differed significantly in frequency between EHD-positive and EHD-negative deer. In the EHD-positive deer, phenylalanine was relatively less likely to be encoded at codon positions 59 and 116, whereas leucine and serine (respectively) were detected less frequently in EHD-negative deer. Both amino acid substitutions were predicted to impact protein structure or function. Understanding associations between TLR3 polymorphisms and EHD provides insights into the role of host genetics in outbreaks of EHD in deer, which may allow wildlife agencies to better understand the severity of outbreaks.

Assigning Culicoides larvae to species using DNA barcoding of adult females and phylogenetic associations

BackgroundOrbivirus-induced hemorrhagic diseases cause high mortality in wild and captive white-tailed deer in North America. The role of different Culicoides species in Orbivirus transmission outside of areas of intensive animal production has not been established. At our study location, bluetongue virus (BTV) RNA-positive female Culicoides debilipalpis pools have been detected annually since 2012 when BTV transmission was noted in a captive deer herd. Identifying specific larval habitats of suspected vectors at active transmission sites is crucial both for identifying the source of the vectors and for subsequently planning intervention actions. Since C. debilipalpis larvae are known to develop in tree holes, this study was designed to use DNA barcoding to identify larvae collected from tree holes.MethodsAdult female Culicoides were collected using light or emergence traps and morphologically identified to 11 species. Culicoides sonorensis were also obtained from a laboratory colony. Substrate was collected from tree holes and flooded with water to harvest floating larvae. Total DNA from three to seven adult females per species and 19 larvae was extracted. Two loci of the nuclear 18S ribosomal RNA (rRNA) gene, one locus each of the mitochondrial cytochrome oxidase subunit I (COI) gene and the nuclear 28S rRNA gene were amplified using loci-specific primers.ResultsAll 61 adults were sequenced at each of the four loci under study. Since no single locus delineated all putative species and the COI locus yielded unreliable pseudogenes for two individuals of C. arboricola, sequences of all four loci were concatenated to maximize species separation and allow for larval association with identified adults. Sixteen larvae were clearly assigned to species based on DNA barcoding and phylogenetic results. Multiple larvae were assigned to each of the C. debilipalpis clade, the C. villosipennis clade, the C. arboricola clade and the C. nanus clade.ConclusionsOf the approximately 62 species described in the southeast USA, 21 have now been barcoded and sequences are publicly available. In this study, we constructed a database composed of species-specific sequences of adult Culicoides and then identified larvae to species by matching their corresponding sequences with adults. Since Culicoides larvae are difficult to identify, using DNA barcoding to facilitate larval habitat surveys can be a valuable tool.Graphical

Compensatory human and predator risk trade-offs in neonatal white-tailed deer

Neonatal mortality is a primary determinant of ungulate population dynamics and occurs from multiple proximal causes, but few studies have compared relationships between risk factors and cause-specific mortality. We evaluated how landscape and physiological characteristics influenced white-tailed deer ( Odocoileus virginianus ) fawn risk from predators (American black bears [ Ursus americanus ], bobcats [ Lynx rufus ], coyotes [ Canis latrans ], and wolves [ Canis lupus ]), anthropogenic causes, and non-predation natural causes (i.e ., disease, injury, or starvation). We monitored 363 fawns and identified 166 mortalities in the Upper Peninsula of Michigan, USA during 2009–2019. Human development reduced fawn predation, particularly from coyotes, but predation was compensated by vehicle collisions. Coyote predation also was reduced in more forested areas, which was offset by increased predation from black bears, bobcats, and wolves. Smaller birth mass increased risk of non-predation natural mortality but did not influence predation or anthropogenic mortality. Our results suggest that for prey living alongside human development, the survival advantage of a “human shield” from predation can be offset by anthropogenic mortality. Birth mass relationships with mortality contradicted the hypothesis that predators select weaker individuals. We conclude that landscape attributes and fawn characteristics may interact with top-down, bottom-up, and anthropogenic processes to shape neonatal white-tailed deer mortality. Because some causes of mortality have opposing relationships with risk factors, combined mortality risk assessment may mask the processes driving specific mortality causes.

Implementing wildlife fences along highways at the appropriate spatial scale: A case study of reducing road mortality of Florida Key deer

Florida Key deer mortality data (1966–2017) showed that about 75% of all reported deer mortalities were related to collisions with vehicles. In 2001–2002, the eastern section of US Hwy 1 on Big Pine Key (Florida, USA) was mitigated with a wildlife fence, 2 underpasses, and 4 deer guards. After mitigation, the number of reported Key deer road mortalities reduced substantially in the mitigated section, but this was negated by an increase in collisions along the unmitigated section of US Hwy 1 on Big Pine Key, both in absolute numbers and expressed as a percentage of the total deer population size. The data also showed that the increase in Key deer collisions along the unmitigated highway section on the island could not be explained through an increase in Key deer population size, or by a potential increase in traffic volume. The overall Key deer road mortality along US Hwy 1 was not reduced but was moved from the mitigated section to the nearby unmitigated section. Thus, there was no net benefit of the fence in reducing collisions. After mitigation, a significant hotspot of Key deer-vehicle collisions appeared at the western fence-end, and additional hotspots occurred further west along the unmitigated highway. Exploratory spatial analyses led us to reject the unmitigated highway section on Big Pine Key as a suitable control for a Before-After-Control-Impact (BACI) analysis into the effectiveness of the mitigation measures in reducing deer-vehicle collisions. Instead, we selected highway sections west and east of Big Pine Key as a control. The BACI analysis showed that the wildlife fence and associated mitigation measures were highly effective (95%) in reducing deer-vehicle collisions along the mitigated highway section. Nonetheless, in order to reduce the overall number of deer-vehicle collisions along US Hwy 1, the entire highway section on Big Pine Key would need to be mitigated. However, further mitigation is complicated because of the many buildings and access roads for businesses and residences. This case study illustrates that while fences and associated measures can be very effective in reducing collisions, wildlife fences that are too short may result in an increase in collisions in nearby unmitigated road sections, especially near fence-ends. Therefore it is important to carefully consider the appropriate spatial scale over which highway mitigation measures are implemented and evaluated.

Role of wild animals in epizootology of infectious diseases inYakutia

It is known that wild animals and birds can be reservoirs and carriers of many infectious diseases of animals and humans. A cadastre of disadvantaged anthrax settlements was developed based on the study of epizootology, which will help optimize epizootological and epidemiological measures for the prevention of anthrax in animals (wild and domestic) and the population. We first identified yersinia (Yersinia enterocolitica and Yersinia pseudotuberculosis) from the material for shooting moose and roe deer living in the Central zone of Yakutia. Antibodies to the serogroups Leptospira Pomona, Grippotyphosa, and Icterohaemorrhagiae serogroups were detected in forest bisons exported from Canada to Yakutia for acclimatization. We developed a method for sampling frozen urine with snow at low temperatures (minus 10-50 ?С) to diagnose leptospirosis of wild animals and dogs, in places of natural habitat of wild mammals (without seizure and capture). The bactericidal effect of the probiotic strains of bacteria Bacillus subtilis TNP-3 and TNP-5 on the causative agent of leptospirosis of various serological groups has been established. The methods are protected by the Russian Federation patents for the invention. There was marked disease and mortality of roe deer from salmonellosis caused by Sal. abortus equi. There has been established the circulation of viruses of infectious rhinotracheitis, diarrhea in the deer population of the Arctic regions, the causative agents of which may be migratory birds and animals of the disadvantaged settlements. In the period of intensive exploration of Actica, climate warming and changes in the fauna, the migration routes of wild animals and birds, growing threat of zoonoses it is necessary to conduct large-scale monitoring of infections, especially viral diseases.

Understanding environmental patterns of canid predation on white-tailed deer (Odocoileus virginianus)

The outcome of encounters between predators and prey affects predation rates and ultimately population dynamics. Determining how environmental features influence predation rates helps guide conservation and management efforts. We studied where gray wolves (Canis lupus Linnaeus, 1758) and coyotes (Canis latrans Say, 1823) killed white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) in northern Wisconsin, USA. We monitored 499 white-tailed deer for cause-specific mortality between 2011 and 2014 using VHF radio collars. We investigated the locations of 125 deer mortalities and determined that 63 were canid (wolf or coyote) kill sites. We analyzed spatial patterns of kill sites using resource selection functions in a model selection framework, incorporating environmental variables including vegetative cover, human development, snow depth, and water. We found no evidence that vegetative cover or human development affected predation risk; however, we did find that increasing snow depth resulted in increased relative predation risk. This finding is consistent with existing research on the influence of snow cover on white-tailed deer survival. Our results suggest that understanding the spatial and temporal patterns of white-tailed deer predation requires a better understanding of snow depth variation in space and time. As climate change scenarios predict changes in snowfall throughout the northern hemisphere, understanding the effect on predator–prey spatial dynamics will be important for management and conservation efforts.

Assessing EDR and a novel deer repellent for reducing by-kill of white-tailed deer (Odocoileus virginianus), during aerial 1080 operations

ABSTRACT A 2014 carcass search survey confirmed that Tiakina Ngā Manu aerial 1080 operations, undertaken to protect resident mohua (Mohoua ochrocephala) from increases to predator populations following substantial beech (Nothofagus sp.) mast events, cause mortality for Wakatipu white-tailed deer. Non-target by-kill of deer generates significant public opposition to predator control operations. We assessed if a current deer repellent (EDR) and a repellent in development (Pestex-DR) were effective at repelling captive white-tailed deer from consumption of nontoxic baits, commonly used in Tiakina Ngā Manu operations. Both repellents were found to significantly decrease bait consumption, and we observed clear displays of aversion to repellent baits by captive deer. Ten GPS collared wild white-tailed deer were then monitored following a Tiakina Ngā Manu operation using EDR in 2016. One collared deer was poisoned following the operation, confirming that EDR is not 100% effective. We recommend the most effective available deer repellent be used for future Tiakina Ngā Manu operations over the Wakatipu white-tailed deer habitat to minimise public opposition to these predator control operations. In addition, our results suggest that differences in the boundary size and shape of operations may account for some of the variability in non-target by-kill observed between studies.

Diagnostic evaluation of unknown white-tailed deer morbidity and mortality in New York State: 2011–2017

White-tailed deer Odocoileus virginianus are the most popular big game animal in the United States. Recreational harvest of these animals is a critical tool in population management, as well as an important financial resource for state economies and wildlife agencies. Thus, herd health evaluations can provide information to wildlife managers tasked with developing sustainable harvest practices while monitoring for emergent problems. The purpose of our study was to document causes of illness and natural mortality in New York white-tailed deer submitted for post mortem evaluation. Animals were presented by members of the public and wildlife management personnel due to abnormal behavior or unexplained death. We describe demographic and seasonal associations among gross and histologic evaluation and diagnostic testing. Post mortem examinations were performed on 735 white-tailed deer submitted for necropsy in New York from January 2011 to November 2017. Causes of euthanasia or mortality were classified into nine categories. The most common findings were bacterial infections, trauma not evident at time of collection, and nutritional issues, primarily starvation. Using a multinomial logistic regression model, we looked for associations between the mortality categories and age, sex and season. Compared to the baseline of bacterial deaths, adults were less likely to have died from nutritional and parasitic causes, males were less likely to have died from other causes, and risk of death from nutritional reasons decreased from season to season, with lowest risk in winter. These methods can help wildlife biologists track changes in disease dynamics over time.

White‐Tailed Deer, Weather and Predation: a New Understanding of Winter Severity for Predicting Deer Mortality

ABSTRACTVariation in white‐tailed deer (Odocoileus virginianus) mortality during winter affects population growth in cold climates. Across the northern extent of their range, mortality increases with colder temperatures and snow. Few studies have examined the relationships between winter conditions and deer mortality, and no studies have concurrently studied this relationship for different ages of deer across multiple years and landscapes. We used recently developed cause‐specific mortality models to evaluate temporal and age‐class variation in deer mortality in farmland areas and compared to published results from forest areas in Wisconsin, USA, from 2011–2014. We then used temporally varying snow and temperature covariates to predict mortality trends using telemetry information from 860 deer. Cause‐specific mortality in the farmland varied by age and year, similar to results from previous research in the forest. Human‐related mortality was the leading cause of mortality in the farmland during most years and ranged from 4.3% to 10.3% for juveniles and 3.6% to 9.1% for adults from 2011–2014. Very little predation occurred in the farmland, and this differed from previous research in the forest where predation was the leading cause of mortality. During more severe winters (2013 and 2014), other mortality, usually associated with starvation, was the leading cause of mortality for juveniles in the farmland but not adults. In the forest, we found support for saturating effects of accumulated snow depth days >30.5 cm and accumulated temperature days >0°C on mortality. We also found support for the relationship of mortality with accumulated temperature days >0°C in the farmland but no relationship with snow depth. Deer tolerate sustained cold temperatures, but the timing of winter to spring transition is more important for deer survival in both forested and agricultural areas. In the absence of empirical survival information, managers can use our model to predict annual winter effects on deer survival, which can provide improved inference compared to traditional winter severity indices. Our results suggest changes in predator abundance may have minor influence on overwinter survival compared to winter weather. Based on mortality estimates from previous research, the highest predation rates on juvenile deer in the forest occurred when wolf (Canis lupus) counts were lowest and when wolf abundance was highest, juvenile deer predation rates were lowest. © 2021 The Wildlife Society.

Mule Deer Migrations and Highway Underpass Usage in California, USA

ABSTRACTRoadways may pose barriers to long‐distance migrators such as some ungulates. Highway underpasses mitigate wildlife‐vehicle collisions and can be an important management tool for protecting migration corridors. In northern California, 3 underpasses were built on United States Route 395 (Route 395) in Hallelujah Junction Wildlife Area (HJWA) in the 1970s for a migratory mule deer (Odocoileus hemionus) herd that had been negatively affected by highway traffic. To determine whether these underpasses were still reducing mule deer mortalities >40 years after construction, we investigated deer use of the underpasses from 2006–2019 using cameras, global positioning system (GPS) collars, and roadkill records. We used occupancy models, approximations of GPS‐collared mule deer movement paths, and roadkill locations to estimate the highway crossing patterns of deer. From camera data, there was higher use of the underpasses by deer during migration (spring [Mar–Jun], fall [Oct–Dec]) than in summer (Jul–Sep), when only resident deer were present. Higher underpass usage occurred in the spring compared to fall migrations. Eleven of 21 GPS‐collared migrating mule deer crossed Route 395. We estimated 30% of the crossings (by 7 of the 11 deer) occurred south of the underpasses where deer could easily access the highway because of short (1‐m high) and deteriorating highway fencing. Roadkill data confirmed that deer‐vehicle collisions were occurring south of the underpasses and at the underpasses. This was likely due to deteriorating infrastructure at the underpasses that allows wildlife access to the highway. Overall, our study indicated that although underpasses can provide safe passage for migratory deer decades (>40 yr) after their construction, deteriorating infrastructure such as fencing and gates can lead to wildlife mortalities on highways near underpasses. © 2021 The Wildlife Society.

Sudden Mortality in Captive White-Tailed Deer With Atypical Infestation of Winter Tick.

In October 2020, three captive male white-tailed deer, Odocoileus virginianus [Zimmermann] (artiodactyla: Cervidae), were found dead in central Pennsylvania and a fourth was euthanized due to extreme lethargy. The deer presented with high burdens of Dermacentor albipictus (Packard) (Ixoda: Ixodidae) (winter tick). There were no other clinical symptoms and deer were in otherwise good physical condition with no observed alopecia. Winter tick epizootics have been associated with mortalities of moose, Alces alces [Linnaeus] (artiodactyla: cervidae), and more recently elk, Cervus canadensis [Erxleben] (artiodactyla: cervidae), in Pennsylvania, but have not been reported in white-tailed deer. Mild winters are favorable to winter ticks and deer producers and managers should be aware of possible infestations as a result.

Twenty Years of Passive Disease Surveillance of Roe Deer (Capreolus capreolus) in Slovenia.

Simple SummaryWildlife can serve as a reservoir for highly contagious and deadly diseases, many of which are infectious to domestic animals and/or humans. Wildlife disease surveillance can be considered an essential tool to provide important information on the health status of the population and for the protection of human health. Between 2000 and 2019, examinations of 510 roe deer carcasses were conducted by comprehensive necropsy and other laboratory tests. In conclusion, the results of this research indicate a broad spectrum of roe deer diseases, but no identified disease can be considered a significant health threat to other wildlife species and/or to humans.In this paper, we provide an overview of the causes of death of roe deer (Capreolus capreolus) diagnosed within the national passive health surveillance of roe deer in Slovenia. From 2000 to 2019, postmortem examinations of 510 free-ranging roe deer provided by hunters were conducted at the Veterinary Faculty, Slovenia. A comprehensive necropsy was performed. According to the results of the necropsy, the samples were subjected to microscopic, histopathological, bacteriological, parasitological, or virological examination. The most frequent causes of death in roe deer were infectious diseases (67%), followed by noninfectious diseases (28%). Of all deaths, parasitic infections represented 48%, bacterial infections 14.8%, trauma 12.5%, and metabolic disorders 9.8%. Less frequent causes were diseases like neoplasia and mycotic infections, winter starvation, hernias, and lightning strike. This study covered an estimated 1% of the total disease-related mortality of roe deer in Slovenia. Comparisons of sex/age structure indicated that hunters did not provide random samples (e.g., young males were disproportionately represented). Therefore, such monitoring does not ensure an unbiased assessment of the significance of the individual disease for the mortality of the population; however, it can provide credible evidence of whether or not a particular disease is present in a population. We show that no identified disease in roe deer in Slovenia can be considered a significant health threat to roe deer, other wildlife species, or humans.

Survival is negatively associated with glucocorticoids in a wild ungulate neonate.

It is unknown how ungulate physiological responses to environmental perturbation influence overall population demographics. Moreover, neonatal physiological responses remain poorly studied despite the importance of neonatal survival to population growth. Glucocorticoid (GC) hormones potentially facilitate critical physiological and behavioral responses to environmental perturbations. However, elevated GC concentrations over time may compromise body condition and indirectly reduce survival. We evaluated baseline salivary cortisol (CORT; a primary GC in mammals) concentrations in 19 wild neonatal white-tailed deer (Odocoileus virginianus) in a northern (NS) and southern (SS) area in Pennsylvania. After ranking survival models consisting of variables hypothesized to influence neonate survival (i.e. weight, sex), the probability of neonate survival was best explained by CORT concentrations, where elevated CORT concentrations were associated with reduced survival probability to 12 weeks of age. Cortisol concentrations were greater in the SS where predation rates and predator densities were lower. As the first evaluation of baseline CORT concentrations in an ungulate neonate to our knowledge, this is also the first study to demonstrate CORT concentrations are negatively associated with ungulate survival at any life stage. Glucocorticoid hormones could provide a framework in which to better understand susceptibility to mortality in neonatal white-tailed deer.

SPATIAL VARIATION OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) POPULATION IMPACTS AND RECOVERY FROM EPIZOOTIC HEMORRHAGIC DISEASE.

Epizootic hemorrhagic disease (EHD) is the most significant source of viral disease-related mortality in white-tailed deer (Odocoileus virginianus) in the US. Deer mortality from EHD has increased in the state of Michigan, US, since 2006, with the largest outbreak occurring in 2012. The 2012 outbreak provided an opportunity to evaluate how this disease affected EHD-related mortality in deer populations at a spatial scale typical of that expected for the greatest disease risk. Our objectives were to quantify the population impacts and spatial extent of EHD associated with areas of disease risk for deer populations and to determine how populations recovered over time following localized EHD impacts. We estimated the annual local abundance of deer for 5 yr immediately following a recent EHD outbreak. Because proximity to wetlands may affect EHD occurrence, we surveyed deer at varying distances (about 1 km and 5 km) from a riparian corridor to determine spatial variation in population impacts. Further, we assessed differences in deer abundance for sites affected and unaffected by EHD. Abundance estimates were lower along transects near the riparian corridor only in the affected area, reflecting EHD mortality associated with wetlands. The only change in abundance over time was a significant increase in the riparian strata in the EHD-affected site.

Evaluating Indirect Effects of Hunting on Mule Deer Spatial Behavior

ABSTRACTMule deer (Odocoileus hemionus) are widely hunted throughout western North America and are experiencing population declines across much of their range. Consequently, understanding the direct and indirect effects of hunting is important for management of mule deer populations. Managers can influence deer mortality rates through changes in hunting season length or authorized tag numbers. Little is known, however, about how hunting can affect site fidelity patterns and subsequent habitat use and movement patterns of mule deer. Understanding these patterns is especially important for adult females because changes in behavior may influence their ability to acquire resources and ultimately affect their productivity. Between 2008 and 2013, we obtained global positioning system locations for 42 adult female deer at the Starkey Experimental Forest and Range in northeast Oregon, USA, during 5‐day control and treatment periods in which hunters were absent (pre‐hunt), present but not actively hunting (scout and post‐hunt), and actively hunting male mule deer (hunt) on the landscape. We estimated summer home ranges and 5‐day use areas during pre‐hunt and hunt periods and calculated overlap metrics across home ranges and use areas to assess site fidelity within and across years. We used step selection functions to evaluate whether female mule deer responded to human hunters by adjusting fine‐scale habitat selection and movement patterns during the hunting season compared to the pre‐hunt period. Mule deer maintained site fidelity despite disturbance by hunters with 72 ± 4% (SE) within‐year overlap between summer home ranges and hunt use areas and 54 ± 7% inter‐annual overlap among pre‐hunt use areas and 56 ± 7% among hunt use areas. Mule deer diurnal movement rates, when hunters are active on the landscape, were higher during the hunting period versus pre‐hunt or scout periods. In contrast, nocturnal movement rates, when hunters are inactive on the landscape, were similar between hunting and non‐hunting periods. Additionally, during the hunt, female mule deer hourly movements increased in areas with high greenness values, indicating that mule deer spent less time in areas with more vegetative productivity. Female mule deer maintained consistent habitat selection patterns before and during hunts, selecting areas that offered more forest canopy cover and high levels of vegetative productivity. Our results indicate that deer at Starkey are adopting behavioral strategies in response to hunters by increasing their movement rates and selecting habitat in well‐established ranges. Therefore, considering site fidelity behavior in management planning could provide important information about the spatial behavior of animals and potential energetic costs incurred, especially by non‐target animals during hunting season. © 2020 The Wildlife Society.