Deer Populations 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.

Roe Deer Reproduction in Western Poland: The Late Autumn Rut Phenomenon

Roe deer (Capreolus capreolus L.) populations in Poland are characterized by low productivity, which is why their reproductive potential was investigated. The presence of corpora lutea (CL) on the ovaries of females hunted in autumn and winter in the years 2015 and 2016 was assessed. Most animals were post-rut and most often had multiple ovulations. However, in early autumn 2015, 60% of the females had no CL. Therefore, they did not participate in mating at the turn of July/August. Those that did ovulate were found to have one CL. In late autumn, 97% of the females were post-rut, mostly with twin ovulations. This confirmed the occurrence of a late autumn rut. This phenomenon had been suggested in studies but not confirmed. In contrast, almost 100% of roe deer ovulated in summer in 2016. It was hypothesized that the reason for the low mating activity of roe deer in the summer of 2015 was heat stress and limited food resources. The summer was exceptionally hot, with many days in July and August when temperatures exceeded 30 °C. The heat combined with low rainfall led to extreme drought. Meanwhile, July and August are the months of mating activity for roe deer. The late autumn rut allowed the roe deer—a monoestrous species—to limit the consequences of a decrease in mating activity or fertility during the hot summer. Global warming may affect roe deer reproduction, so climatic conditions should be considered in population studies, not only in terms of food availability.

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.

Montane willow scrub restoration in Scotland: reviewing 30 years of progress to reestablish the altitudinal treeline

Many mountain woodlands across the globe have undergone anthropogenic degradation with negative implications for the ecological and socioeconomic systems dependent on them. Montane willows are arctic‐alpine species of high nature conservation concern within the altitudinal treeline. Scotland has been pioneering the restoration of montane willow scrub for three decades following widespread loss linked particularly to overgrazing by sheep and deer since the eighteenth century. In the 1990s, the total area of montane willows throughout the country was less than 10 ha, with most remaining populations highly fragmented, in rapid decline, and restricted to inaccessible cliffs. Subsequently, montane willow scrub restoration has been part of an overall 2659 ha area managed for the recovery of mountain woodlands in Scotland. By May 2023, 396,868 montane willows were planted in projects encompassing large‐scale habitat creation, relict population reinforcement by genetic rescue, fencing, and landscape‐scale management for low‐density deer populations. This review summarizes restoration methods and outcomes with case study examples to promote conservation evidence and research on plant growth and survival, planting sites, associated biodiversity, molecular ecology, genomics, and long‐term population sustainability. With the potential for montane scrub restoration to be widely expanded, improved connectivity to revive a treeline mosaic shaped by regeneration will tackle biodiversity loss and help mitigate climate change impacts on a national scale. However, caution must be applied to creating definitions of distinct habitats for restoration that are based on non‐natural or ecologically degraded systems. These experiences are particularly relevant to montane and circumpolar regions with strongly modified landscape histories.

Body mass change over winter is consistently sex-specific across roe deer (Capreolus capreolus) populations

Body mass change over winter is consistently sex-specific across roe deer (Capreolus capreolus) populations

Annual variation in recruitment rates for the sika deer (Cervus nippon) population in eastern Hokkaido, Japan

Annual variation in recruitment rates for the sika deer (<i>Cervus nippon</i>) population in eastern Hokkaido, Japan

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.

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.

Comparison of thermal cameras and human observers to estimate population density of fallow deer (Dama dama) from aerial surveys in Tasmania, Australia

Context The population of introduced fallow deer (Dama dama) is thought to have increased exponentially across much of the island of Tasmania, Australia, since 2000. Historically, deer management decisions have relied on population trend data from vehicular spotlight surveys. Renewed focus on the contemporary management of the species requires development of more robust and precise population estimation methodology. Aims This study demonstrates two aerial survey methods – conventional counts by trained human observers, and thermal imaging footage recorded during the same flights – to inform future survey practices. Methods Conventional counts were carried out by three observers, two seated on the left side of the helicopter, and one on the right. A high-resolution thermal camera was fitted to the helicopter and was orientated to meet the assumptions of distance sampling methodologies. Both survey methods were used to generate deer population density estimates. Spatial distribution of deer was also analysed in relation to patches of remnant native vegetation across an agricultural landscape. Mark–recapture distance sampling was used to estimate density from human observer counts and provide a comparison to the distance sampling estimates derived from the thermal camera. Key results Human observer counts gave a density estimate of 2.7 deer per km2, while thermal camera counts provided an estimate of 2.8 deer per km2. Deer population density estimates calculated via both methods were similar, but variability of the thermal camera estimate (coefficient of variation (CV) of 36%) was unacceptably high. Human observer data was within acceptable bounds of variability (CV, 19%). The estimated population size in central and north-eastern Tasmania for 2019 approximated 53,000 deer. Deer were primarily congregated within 200 metres of the interface between canopy cover and open pasture. Conclusions The population density estimate provides a baseline for monitoring and managing the Tasmanian deer population. Human observer data was more precise than thermal camera data in this study, but thermal counts could be improved by reducing sources of variability. Implications Improvements for the collection of thermal imagery are recommended. Future control efforts may be more efficient if they preferentially target habitat edges at this time of year, paired with random or grid-based searches where population density is lower.

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.

Antler size in red deer: declining selection and increasing genetic variance with age, but little senescence

Abstract While senescence is a common occurrence in wild populations, not all traits decline with age simultaneously and some do not show any senescence. A lack of senescence in secondary sexual traits is thought to be due to their importance for reproductive success. However, if reproductive success senesces, why would secondary sexual traits apparently not senesce? Here, we explored this question in a wild population of red deer (Cervus elaphus) using antler form (number of points), a secondary sexual trait which shows little senescence, despite the occurrence of reproductive senescence. In line with expectations for traits that senesce, genetic variance in antler form increased with age and selection weakened with age. Therefore, there was no indication that a stronger selection on individuals that survived to older ages was countering the dilution of selection due to fewer individuals being alive. Furthermore, the effect of selective disappearance masking a slight decline in antler form in the oldest years was small. Interestingly, although genetic variance and positive selection of antler form were found, there was no evidence of a response to selection, supporting a genetic decoupling of antler senescence and reproductive senescence. Finally, a positive genetic covariance in antler form among age classes provides a possible explanation for the lack of senescence. These findings suggest that the antler form is under a genetic constraint that prevents it from senescing, providing an interesting evolutionary explanation for negligible senescence in a secondary sexual trait, and consequently, the existence of asynchrony in senescence among traits within populations.

Site fidelity trumps disturbance: aerial shooting does not cause surviving fallow deer (Dama dama) to disperse

Context Aerial shooting is an important tool for managing the economic and environmental impacts of widespread wild fallow deer populations in eastern Australia and could be crucial for mounting an effective response to an emergency animal disease incursion. However, there is a concern that the disturbance caused by aerial shooting could cause infected animals to disperse, thereby transmitting pathogens to previously uninfected areas. Aims We sought to describe the nature and extent of spatial behavioural changes in fallow deer exposed to aerial shooting to: (1) assess the risk that aerial shooting poses to disease spread, and (2) better understand how aerial shooting can contribute to routine deer management programs. Methods We contrasted movement rates, activity range areas, and daily activity patterns of 48 GPS-collared fallow deer before, during and after exposure to aerial shooting at three sites in New South Wales. Key results No collared deer left its pre-shoot activity range area during shooting or within 30 days after shooting finished. Observed behaviour changes included increased daily and hourly distance travelled by female deer during and after shooting, increased activity range areas for female deer after shooting, and increased nocturnal activity in female and male deer during shooting. However, observed changes were minor, temporary, localised, and variable among sites. Conclusions Collared deer showed strong site fidelity despite repeated intense disturbance and substantial population reductions. We found no evidence to support concerns that aerial shooting poses a hazard of disease spread. Implications Aerial shooting should be retained as a key control tool for managing wild fallow deer populations in Australia, including for reducing disease host population densities in the event of an emergency animal disease incursion.

Seed dispersal of Zoysia japonica by sika deer: An example of the “foliage is the fruit” hypothesis

AbstractZoysia japonica, a low growing grass, is tolerant to grazing and trampling. Kinkazan Island in northern Japan is inhabited by sika deer (Cervus nippon). The deer population increased in the 1970s at a shrine garden in the western part of the island, leading to expansion of Zoysia swards around the shrine garden and their colonization of remote open patches. The expansion around the garden is due to elongation of the rhizome, but expansion to remote places may be due to endozoochory by deer. This appears to be a good example of the “foliage is the fruit” hypothesis (the FF hypothesis) proposed by Janzen (1984; American Naturalist 123:338–353). To demonstrate this, we confirmed the expansion of the Zoysia swards and tested the traits of Zoysia by field surveys and indoor experiments. The Zoysia peduncles stood among the leaves, and sika deer fed on both the seeds and leaves. One deer fecal pellet contained about 20 seeds at its peak in June. In the feeding experiment, the survival rate through digestion was 38%. In the greenhouse experiment, the germination rate was 72%. An outdoor experiment showed that germination rates of the ingested seeds were 5% in a dark habitat and 58% in a bright habitat. Zoysia exhibited many of the traits presented by the FF hypothesis, and sika deer functioned as seed dispersal agents. Therefore, the Zoysia—sika deer relationship seems to support the FF hypothesis.

Climate change and deer in boreal and temperate regions: From physiology to population dynamics and species distributions.

Climate change causes far-reaching disruption in nature, where tolerance thresholds already have been exceeded for some plants and animals. In the short term, deer may respond to climate through individual physiological and behavioral responses. Over time, individual responses can aggregate to the population level and ultimately lead to evolutionary adaptations. We systematically reviewed the literature (published 2000-2022) to summarize the effect of temperature, rainfall, snow, combined measures (e.g., the North Atlantic Oscillation), and extreme events, on deer species inhabiting boreal and temperate forests in terms of their physiology, spatial use, and population dynamics. We targeted deer species that inhabit relevant biomes in North America, Europe, and Asia: moose, roe deer, wapiti, red deer, sika deer, fallow deer, white-tailed deer, mule deer, caribou, and reindeer. Our review (218 papers) shows that many deer populations will likely benefit in part from warmer winters, but hotter and drier summers may exceed their physiological tolerances. We found support for deer expressing both morphological, physiological, and behavioral plasticity in response to climate variability. For example, some deer species can limit the effects of harsh weather conditions by modifying habitat use and daily activity patterns, while the physiological responses of female deer can lead to long-lasting effects on population dynamics. We identified 20 patterns, among which some illustrate antagonistic pathways, suggesting that detrimental effects will cancel out some of the benefits of climate change. Our findings highlight the influence of local variables (e.g., population density and predation) on how deer will respond to climatic conditions. We identified several knowledge gaps, such as studies regarding the potential impact on these animals of extreme weather events, snow type, and wetter autumns. The patterns we have identified in this literature review should help managers understand how populations of deer may be affected by regionally projected futures regarding temperature, rainfall, and snow.

Analysis of the genetic diversity of Tahe red deer and population structure of Cervus elaphu/hanglu/canadensis

The Tahe red deer is currently the largest breeding population of antlered Cervus elaphus in China. It has unique characteristics such as drought and roughage tolerance, high antler yield and early sexual maturity. It is a high-quality provenance for cultivating high-yield Cervus elaphus breeds and is also the subject of study on the origin, evolution, and classification of Cervus elaphus. The breeding quantity of Tahe red deer has decreased significantly in recent years due to the influence of feeding conditions and consumer market. This has resulted in a serious threat to its genetic resources. To provide a scientific theoretical basis for the protection of the Tahe red deer population, we performed PCR amplification and direct sequencing of the AMELY2, DBY and SRY genes of the Y chromosome, and the ND1, COX1, ATP6, ND5, Cyt b and D-loop regions of the mtDNA, and analysed their genetic diversity and population genetic structure. The results showed high haplotype diversity and low nucleotide diversity in both the Y chromosome and mtDNA genes. The phylogenetic tree and haplotype network diagram, constructed using white-lipped deer as the outgroup, indicate that Tahe red deer has two distinct ancestral types. The phylogenetic tree, based on the Cyt b gene and D-loop region, reveals that the Cervus elaphus/hanglu/canadensis is divided into three clades: western, central, and eastern. Tahe red deer, C.h.bactrianus, and C.h.hanglu are clustered in the central clade. The study results indicate that Tahe red deer has low genetic diversity and two distinct ancestor types. It is speculated that the central clade is either the earliest differentiation from the ancestor species or the closest to it.

Insights from homozygous signatures of cervus nippon revealed genetic architecture for components of fitness.

This study investigates the genomic landscape of Sika deer populations, emphasizing the detection and characterization of runs of homozygosity (ROH) and their contribution towards components of fitness. Using 85,001 high-confidence SNPs, the investigation into ROH distribution unveiled nuanced patterns of autozygosity across individuals especially in 2 out of the 8 farms, exhibiting elevated ROH levels and mean genome coverage under ROH segments. The prevalence of shorter ROH segments (0.5-4Mb) suggests historical relatedness and potential selective pressures within these populations. Intriguingly, despite observed variations in ROH profiles, the overall genomic inbreeding coefficient (FROH) remained relatively low across all farms, indicating a discernible degree of genetic exchange and effective mitigation of inbreeding within the studied Sika deer populations. Consensus ROH (cROH) were found to harbor genes for important functions viz., EGFLAM gene which is involved in the vision function of the eye, SKP2 gene which regulates cell cycle, CAPSL involved in adipogenesis, SPEF2 which is essential for sperm flagellar assembly, DCLK3 involved in the heat stress. This first ever study on ROH in Sika deer, to shed light on the adaptive role of genes in these homozygous regions. The insights garnered from this study have broader implications in the management of genetic diversity in this vulnerable species.

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

Assessing population status and influencing factors of alpine musk deer in patchy habitats: Implications for conservation strategies

Musk deer (Moschus spp.) are widely known for its musk and are globally endangered as a result of poaching, habitat loss, and fragmentation. To facilitate restoration of the alpine musk deer (M. chrysogaster) in existing areas, reliable estimates of population size and influencing factors are essential to assess effectiveness of conservation interventions, particularly for isolated musk deer populations in patches. In this paper, we used line transect and camera trap data collected from 2020 to 2022 in the Helan mountains to assess the population status and characterized the influencing factors of alpine musk deer. Our findings indicate that musk deer are patchily distributed in three areas of high elevation, with the population limited to less than 200 individuals, remaining below historic levels (compared to 1995). There was a significant positive correlation between the role of sympatric species on musk deer, with red fox (Vulpes vulpes), badger (Meles meles) and blue eared-pheasant (Crossoptilon auritum) having a significant effect on the out-modeled pathway. Variable but insignificant effects of anthropogenic activities were observed across all species categories, which could be due to mutual adaptation over time. Our results imply that the recovery of sensitive population in island-like habitats remains challenging and may be exacerbated by limited environment and resources. Our study underscores the necessity of establishing ecological corridors to enhance habitat connectivity for alpine musk deer, undertaking conservation genetics research on isolated populations, controlling stray dogs to maintain interspecific balance, and implementing electronic fencing to mitigate human disturbance and resource competition. This study provides basic information for understanding the population status of alpine musk deer and offers insights for conservation efforts.

Red deer grazing pressure on agricultural grass meadows from broad to local scale

Grazing by wildlife on agricultural land is widespread across geographical regions, and can cause human–wildlife conflicts due to reduced crop yield when the grazing pressure is high. Growing red deer Cervus elaphus populations in Europe call for an increased understanding of their grazing patterns to mitigate damages. We quantified how red deer grazing pressure (grazing presence and grazing level) on agricultural grass meadows (n = 60) in Norway varied across multiple spatial scales. We used a nested, hierarchical study design transcending from a broad scale (meadows across the landscape) to intermediate (between nearby meadows) and local (within‐meadow) scales, allowing us to identify at which scale the variation in grazing pressure was strongest. We estimated how grazing was determined by broad‐scale factors influencing forage availability and quality through population density, distance to coastline, and differences between the first versus second harvest, by intermediate‐scale factors in terms of meadow management causing differences in botanical composition and quality, and by local‐scale factors in terms of perceived predation risk and disturbance. At a broad scale, higher population densities were associated with higher grazing pressure, and more grazing occurred before the first compared to the second harvest. Intermediate‐scale factors explained the most variation of grazing pressure from red deer, with higher grazing pressure on newly renewed meadows compared to other nearby meadows. On a local scale, more grazing occurred closer to the forest edge, providing cover, and further away from infrastructure, with increased risk and disturbance. Overall, our study highlights how drivers of grazing pressure on agricultural land vary across spatial scales. Population reductions on a broader scale may have some effect in reducing the grazing pressure, but renewed meadows will nevertheless attract red deer, causing higher grazing pressure compared to neighbouring meadows. This insight is crucial for determining effective mitigation strategies facing rising red deer populations across Europe.