Deer Abundance Research Articles

When is lethal deceptive pollination maintained? A population dynamics approach.

Not all plant-pollinator interactions are mutualistic, and in fact deceptive pollination systems are widespread in nature. The genus Arisaema has a pollination system known as lethal deceptive pollination, in which plants not only attract pollinating insects without providing any rewards, but also trap them until they die. Many Arisaema species are endangered from various disturbances, including reduction in forest habitat, modification of the forest understorey owing to increasing deer abundance, and plant theft for horticultural cultivation. We aimed to theoretically investigate how lethal deceptive pollination can be maintained from a demographic perspective and how plant and pollinator populations respond to different types of disturbance. We developed and analysed a mathematical model to describe the population dynamics of a deceptive plant species and its victim pollinator. Calibrating the model based on empirical data, we assessed the conditions under which plants and pollinators could coexist, while manipulating relevant key parameters. The model exhibited qualitatively distinct behaviours depending on certain parameters. The plant becomes extinct when it has a low capability for vegetative reproduction and slow transition from male to female, and plant-insect co-extinction occurs especially when the plant is highly attractive to male insects. Increasing deer abundance has both positive and negative effects because of removal of other competitive plants and diminishing pollinators, respectively. Theft for horticultural cultivation can readily threaten plants whether male or female plants are frequently collected. The impact of forest habitat reduction may be limited compared with that of other disturbance types. Our results have emphasized that the demographic vulnerability of lethal deceptive pollination systems would differ qualitatively from that of general mutualistic pollination systems. It is therefore important to consider the demographics of both victim pollinators and deceptive plants to estimate how endangered Arisaema populations respond to various disturbances.

Wolf-related damage in livestock management: Long-term data analyses in Saxony, Germany

The increasing number of wolves (Canis lupus) in Central Europe has increased wolf-livestock conflicts. Several studies have analysed the impact of herding styles and the possible influencing factors. However, short analysis periods and focusing on specific influencing factors can lead to ambiguous or contradictory results. This study used long-term data from 2000 to 2019 in the federal state of Saxony (Germany) to evaluate a broad range of potential influencing factors, thereby identifying critical factors that considerably impact the likelihood of livestock attacks or the extent of livestock damage due to wolves. Generalised linear models were used for modelling. Our analyses showed that small livestock were more at risk of wolf attacks when (1) the percentage of woodland in comparison to agricultural land was low, (2) wolf territories were in proximity, and (3) the abundance of red deer was low. In addition, wolf attacks were associated with more livestock damage when (1) sika and red deer were abundant, (2) livestock were held in small herds, and the number of farms was low, (3) protective measures were missing, and (4) packs held juvenile wolves. The information on fencing style, independent of the occurrence of wolf attacks, would significantly improve future research and may help minimise conflicts between wolves, livestock, and humans.

Exclosure from browsing by invasive ungulates increases species richness and diversity of ground flora in rainforests of New Caledonia

Introduced ungulates can impact forest structure and composition. We tested in rainforests of New Caledonia if exclosure of invasive ungulates (Javan rusa deer Rusa timorensis russa and feral pigs Sus (scrofa) domesticus) increased abundance, species richness and diversity of native plants by comparing 19 plots of 10 m2 in four study areas that were protected from browsing for 7 years with 76 unprotected plots. Abundance, species richness and diversity of native plants of 20–60 cm of height were higher in protected plots compared to unprotected plots. We attribute the measured negative impact mainly to deer as the positive effect of exclosures was highest in the study area with the highest deer abundance and browsing rate. The exclosures were also beneficial in a secondary forest with medium deer abundance whereas in old-growth forest with medium deer abundance we could not detect an effect of the exclosures. We conclude that protecting even small areas from browsing by invasive ungulates can increase biodiversity and that exclosures are most beneficial at high deer abundance and in secondary habitats.

Intensive professional vehicle-based shooting provides local control of invasive rusa deer in a peri-urban landscape

Non-native deer are becoming increasingly common in peri-urban landscapes, where they pose a risk to the health and wellbeing of people. Professional vehicle-based shooting is commonly used to control deer populations in these complex landscapes, but the effectiveness and cost of this method have seldom been evaluated. We analyzed the effectiveness and cost of using professional vehicle-based shooting to reduce the abundance and impacts of non-native rusa deer (Cervus timorensis) in a peri-urban landscape in Wollongong, eastern Australia, during 2011–2021. We incorporated the results from an independent monitoring program into a Bayesian joint-likelihood framework to model spatio-temporal changes in rusa deer abundance. Finally, we used our findings to assess the effect of the management program on the number of complaints from the residents. After eleven years and the removal of 4701 rusa deer from Wollongong LGA (712 km2), deer abundance did not change in 74.7% of the area, decreased in 19.4% of the area (mostly in and around the sites where the professional shooting occurred), and increased in 5.9% of the area. Shooting was most cost-effective during winter when the longer hours of darkness meant that shooters could visit more sites. In contrast to deer abundance, the probability of residents complaining about deer increased in space and time. Our study shows that professional vehicle-based shooting can locally reduce the abundance of invasive deer in a peri-urban landscape, providing that sufficient control effort is expended. We suggest that shooting effort is currently too thinly spread across this peri-urban landscape, and that concentrating shooting effort on the areas of greatest deer abundance and resident complaints might be a more cost-effective strategy for managing invasive deer in peri-urban landscapes.

Urbanization and primary productivity mediate the predator–prey relationship between deer and coyotes

AbstractPredator–prey interactions are important for regulating populations and structuring communities but are affected by many dynamic, complex factors across large scales, making them difficult to study. Integrated population models (IPMs) offer a potential solution to understanding predator–prey relationships by providing a framework for leveraging many different datasets and testing hypotheses about interactive factors. Here, we evaluate the coyote–deer (Canis latrans–Odocoileus virginianus) predator–prey relationship across the state of North Carolina (NC). Because both species have similar habitat requirements and may respond to human disturbance, we considered net primary productivity (NPP) and urbanization as key mediating factors. We estimated deer survival and fecundity by integrating camera trap, harvest, and biological and hunter observation datasets into a two‐stage, two‐sex Lefkovich population projection matrix. We allowed survival and fecundity to vary as functions of urbanization, NPP, and coyote density, and projected abundance forward to test eight hypothetical scenarios. We estimated initial average deer and coyote densities to be 11.83 (95% CI: 5.64, 20.80) and 0.46 (95% CI: 0.02, 1.45) individuals/km2, respectively. We found a negative, though highly uncertain, relationship between the current levels of coyote density and deer fecundity in most areas that became more negative under hypothetical conditions of lower NPP or higher urbanization, leading to lower projected deer abundances. Though not conclusive, our results indicate the possibility that coyotes could have stronger effects on deer populations in NC if their densities rise, but primarily in less productive and/or more suburban habitats. Our case study provides an example of how IPMs can be used to better understand the complex relationships between predator and prey under changing environmental conditions.

Taylor’s law and quasi-experimental hunting of invasive wild boar and axis deer in a protected area of north-eastern Argentina

Context Overabundant ungulate populations frequently cause ecological and economic damage and are difficult to control. Sustained culling efforts at El Palmar National Park have largely reduced wild boar (Sus scrofa) numbers and damage but have failed to halt the ever-increasing abundance of axis deer (Axis axis) for undefined reasons. Multi-year camera-trap surveys indicated a mismatch between deer core activity and the usual timing of hunting sessions. Aim We used the spatial and temporal forms of Taylor’s law (TL, a power relationship between the sample mean and sample variance) to test whether overnight hunting sessions are more effective for culling axis deer and wild boar than are daytime sessions, and assessed whether they modify ungulate harvest composition. Methods We implemented a quasi-experimental trial (i.e. ‘experiments in which units are not assigned to conditions randomly’), including nine alternating blocks of four to seven hunting sessions each (overnight or daytime) in which an average of 42 hunter groups performed controlled shooting over bait from fixed elevated blinds, retrieved, sexed, weighed and measured all quarry. Key results The relationship between the mean and variance of ungulate crude catch per hunting-party session and crude catch per unit effort (CPUE, where effort is measured in hunting-party hours) by hunting shift satisfied the spatial and temporal TL. On average, axis deer catch was 2.39–2.61 times greater in overnight than in daytime sessions, whereas CPUE indices were 1.54–1.73 times greater. For wild boar, overnight sessions returned catches similar to (0.94–1.03×), and a significantly lower CPUE (0.63–0.67×) than for daytime sessions. The harvest indices were substantially aggregated in daytime sessions only, and were consistently skewed towards yearlings or subadults and males, especially among adult deer. Overnight sessions culled proportionally more adults and more pregnant hinds and sows than did daytime sessions, and significantly heavier deer and wild boar males. Conclusions Overnight sessions were substantially more effective for culling deer than were daytime sessions, and selected for individuals with greater fitness. Stage- and male-skewed harvest most likely explains the steady population growth of axis deer despite increasing hunting pressure over a decade. Implications Adjusting the schedule of hunting sessions to time intervals of peak ungulate activity substantially increased the efficiency of management efforts in terms of removal rates and reproductive value of the culled specimens.

Human-Deer Relations during Late Prehistory: The Zooarchaeological Data from Central and Southern Portugal in Perspective.

Human-animal relations have been a fruitful research topic worldwide. The importance of deer in hunter-gatherer societies is undeniable, with cervids being commonly found in archaeological and past artistic records, with a notable amount of information recovered in the Iberian Peninsula. This relevance continues during Late Prehistory, but the attempt to discuss cervids under broader perspectives and based on different types of data is not as common. We intend to approach human-deer relations in Central and Southern Portuguese Late Prehistory by considering the zooarchaeological records, both deer abundance in faunal spectra and their presence in "meaningful" assemblages and structured depositions, as well as the use of deer and deer body parts in other socio-cultural and ideological practices. The synthesis of available data shows that human-deer relations changed through time and space, with different abundances related to hunting depending on chronology and geography. The use of deer or their body parts as a resource of symbolic nature also varied, being included in food-sharing events, offerings, structured depositions, and graphic representations. Changeability is part of the different relationships, ontologies, and cosmogonies that humans and deer developed in the Late Prehistoric relational world.

Roe Deer, Lithuania’s Smallest and Most Abundant Cervid

A review of 113 scientific and other publications on the smallest and most abundant deer in Lithuania, the roe deer (Capreolus capreolus), is presented, along with an analysis based on compound annual population growth rates of population numbers, hunting bags, and roadkill. This review covers the species’ history in the country from the last glaciation onwards, the changes in numbers from 1934 to 2023, hunting bag changes from 1965 to 2022, roadkill numbers from 2002 to 2022, data on roe deer reproduction, habitat selection, genetic diversity, pathogens, and damage to forest stands. It also provides an overview of species management and selection for trophies. Despite the exponential increase in roe deer numbers since 1990 and the dominance of this species in roadkill, even on urban roads, the number and density of animals and the damage they cause to forest stands are relatively low compared to other European countries. Within the observed period, drops in numbers were related to harsh winters in 1969/1970 and 1995/1996. Poaching, especially coinciding with weakened enforcement during the period of political–economic transition in the early 1990s, has also had a negative impact on population numbers, as have recent increases in the number of large predators. Population growth over the recent period does not correlate with hunting mortality, which has remained stable at an average of 16.9% since 2002.

Spatial overlap of gray wolves and ungulate prey changes seasonally corresponding to prey migration

BackgroundPrey are more vulnerable during migration due to decreased familiarity with their surroundings and spatially concentrated movements. Predators may respond to increased prey vulnerability by shifting their ranges to match prey. Moose (Alces alces) and white-tailed deer (Odocoileus virginianus) are primary gray wolf (Canis lupus) prey and important subsistence species for Indigenous communities. We hypothesized wolves would increase use of ungulate migration corridors during migrations and predicted wolf distributions would overlap primary available prey.MethodsWe examined seasonal gray wolf, moose, and white-tailed deer movements on and near the Grand Portage Indian Reservation, Minnesota, USA. We analyzed GPS collar data during 2012–2021 using Brownian bridge movement models (BBMM) in Migration Mapper and mechanistic range shift analysis (MRSA) to estimate individual- and population-level occurrence distributions and determine the status and timing of range shifts. We estimated proportional overlap of wolf distributions with moose and deer distributions and tested for differences among seasons, prey populations, and wolf sex and pack affiliations.ResultsWe identified a single migration corridor through which white-tailed deer synchronously departed in April and returned in October–November. Gray wolf distributions overlapped the deer migration corridor similarly year-round, but wolves altered within-range distributions seasonally corresponding to prey distributions. Seasonal wolf distributions had the greatest overlap with deer during fall migration (10 October–28 November) and greatest overlap with moose during summer (3 May–9 October).ConclusionsGray wolves did not increase their use of the white-tailed deer migration corridor but altered distributions within their territories in response to seasonal prey distributions. Greater overlap of wolves and white-tailed deer in fall may be due to greater predation success facilitated by asynchronous deer migration movements. Greater summer overlap between wolves and moose may be linked to moose calf vulnerability, American beaver (Castor canadensis) co-occurrence, and reduced deer abundance associated with migration. Our results suggest increases in predation pressure on deer in fall and moose in summer, which can inform Indigenous conservation efforts. We observed seasonal plasticity of wolf distributions suggestive of prey switching; that wolves did not exhibit migratory coupling was likely due to spatial constraints resulting from territoriality.

Unveiling activity patterns of the deer Odocoileus virginianus (Artiodactyla: Cervidae) and its predators in Mexico's Arid Region

Introduction: Size, predator presence, and habitat nutritional quality influence herbivorous species' activity patterns and resource utilization. Objectives: This study aims to determine the relative abundance and activity patterns of white-tailed deer (Odocoileus virginianus) and their main predators. Methods: The study was conducted in the WMU "Bienes Comunales Santa Cruz Nuevo" in Totoltepec de Guerrero, Puebla, Mexico. Twenty-two quadrants were randomly selected, and camera traps were installed. Over a two-year period (2018-2020), wildlife visits were recorded to estimate the relative abundance index (RAI), activity patterns, and overlap coefficient (Dhat1) of white-tailed deer and their predators based on their activity schedule. Results: The estimated RAI for deer was 7.2%, while it was 3.4% for coyotes (Canis latrans), 2.3% for bobcats (Lynx rufus), and 0.14% for pumas (Puma concolor). White-tailed deer were observed in 31% of the camera traps, while coyotes were captured in 68% of them. The overlap of the activity schedule, Dhat1, between deer and coyotes was 0.18. In contrast, the activity overlap between foxes and deer was higher (Dhat1: 0.2979; EE 0.037) based on the analysis of variance. The activity pattern of coyotes indicated they were crepuscular, with increased activity during the afternoon and night. However, an increase in activity synchronized with deer's patterns was also observed. The bobcat coincided with deer in 10% of the cameras, but due to the limited number of observations, it was not possible to estimate the activity overlap between these species. Conclusions: The activity overlap between white-tailed deer and foxes is more significant than that of deer and coyotes in this region. The activity overlap between deer and coyotes is lower compared to other parts of the world.

Modelling the spatial abundance of invasive deer and their impacts on vegetation at the landscape scale

Deer populations and their impacts on forest ecosystems are increasing globally. Given the imperative and expense to mitigate impacts of invasive deer, we aimed to elucidate critical drivers of (i) deer density, (ii) deer impacts, and (iii) the relationship between them, to facilitate targeted management. We used quantile regression forests to model deer density (faecal pellet counts at 1948 locations) and impacts (browsing and other impacts on > 23,000 woody plants at 343 locations) across a mosaic of agricultural and forested ecosystems in Victoria, Australia (12,775 km2). Climate, topography, vegetation cover, and distance to water features were included as model covariates. Modelled deer density (r2 = 0.71, MAE = 0.56 pellets/m2) was most influenced by distance to waterbodies (> 10 ha, 31.2%), elevation (14.3%) and woody vegetation cover (12.9%). Modelled deer impact (r2 = 0.32, MAE = 6.9%) was most influenced by deer density (21.0%), mean annual precipitation (12.8%) and elevation (12.2%). Deer density was typically highest near large waterbodies, at low elevation, and with intermediate tree cover (40–70%). Impacts increased steadily with deer density up to ~ 2 pellets/m2. Our study demonstrates the importance of forest water and forest agricultural interfaces for both deer density and impacts. Deer are likely to be most abundant near waterbodies due to the availability of high-quality forage and water, and prefer lowland locations that have access to both open and forested habitats. Spatial models can be used to predict deer density and associated impacts to facilitate targeted invasive deer management.

Changes in Wolf Occupancy and Feeding Habits in the Northern Apennines: Results of Long-Term Predator-Prey Monitoring.

The comprehension of the factors that have influenced the recent changes in wolf (Canis lupus) range and diet that have occurred in our study area, characterized by a highly heterogeneous landscape, can shed light on their current process of expansion toward the plain. Wolf presence was monitored using a standardized protocol from 2007 to 2022 by carrying out eight monitoring sessions organized in seasonal surveys, during which, we collected wolf presence data. To model wolf range dynamics, we used dynamic occupancy models considering land cover types and wild ungulate abundances as covariates. Moreover, we studied the wolf diet through scat analysis, identifying the consumed items from undigested remains. Wolf occupancy in the study area progressed from mountains to lower hills gradually; the observed range dynamics were driven by prey abundance and human presence: in particular, the probability of colonization increased with roe deer (Capreolus capreolus) abundance, whereas the probability of extinction increased with urban areas. The wolf diet showed a gradual shift from the prevalent consumption of wild boar (2007-2008 and 2011-2012) to the prevalent consumption of roe deer (continuously increasing from 2015 onward). Our results might be related to a specific adaptation of the predator to the local ecology of the most consumed species: the roe deer.

Persistence of mule deer pellet groups on Chihuhuan Desert

The persistence of fecal or pellet groups is indispensable when using the pellet group counting technique to estimate population densities and relative abundances of deer, as well as other herbivores. This technique is widely employed worldwide, and in México, the majority of deer abundance estimates have been made using this tool. However, for mule deer (Odocoileus hemonious) in México, there is no data on the persistence of pellet groups, and there is only one study on white-tailed deer. The pellet group counting technique has two main methods: a) "Fecal Standing Crop," where the accumulated pellet groups in plots are counted in a single visit, and b) "Fecal Accumulation Rate," which estimates density based on the accumulation of new fecal groups between two sampling periods, initially requiring the removal of all fecal groups from plots and counting again after some time. Both methods require knowing the pellet group disappearance rate during the pellet group accumulation period. This information is fundamental to understanding the ecology and making precise decisions in the management and conservation of mammals, such as mule deer, a species that is declining in some regions of México. Due to the lack of studies on the persistence of pellet group of mule deer in México, the aim of this study was to determine the persistence of mule deer fecal groups and their color changes over time, to establish pellet accumulation periods for estimating population abundances without biases when using this technique in arid habitats. We monitored 102 fecal groups for four years in the Chihuahuan Desert, finding that pellet groups are only lost during the summer rainy season. All pellet groups deposited between October and May were present, and all pellet groups turned white only after the first summer rainy season. The persistence of pellet groups was similar across seasons (fall, winter, spring) and deposition years (2004 to 2006). Some pellet groups persisted for over four years. The data suggest that the only source of degradation of pellet groups is summer rains, and no degradation by biological agents, such as fungi or insects, was observed. In summary, in arid areas, to estimate deer use or density throughout the entire dry season through pellet group counting, it is suggested that only two visits with either of the mentioned techniques are needed. If "Fecal Standing Crop" is used, there is now certainty that all non-white pellets are post the summer rainy season. If the "Fecal Accumulation Rate" technique is used, there is certainty that there will be no loss of pellets groups between the accumulation period of the entire dry season, approximately 7.5 months later. By reducing the number of visits, it allows us to cover more sampling sites, expand the study area, and obtain more precise estimates that will help understand ecological aspects and make management decisions.

Spatial Variation of Population Density and Age Structure of White-Tailed Deer (Odocoileus virginianus) in a Colombian Moor

Wildlife population density is affected by resource availability, predators and competitors, and anthropogenic stressors. Its analysis and the factors affecting it are important for conservation, use, or population control. Based on estimates of density and population parameters, together with niche modeling, previous studies considered that the white-tailed deer population at the Chingaza National Natural Park (NNP) is undergoing exponential growth due to the marginal influence of factors regulating its abundance, such as predators. The aim of this study was to evaluate the population density and age structure of the white-tailed deer in the Chingaza NNP, Colombia. To evaluate the population density and age structure of white-tailed deer in the Monterredondo and La Paila sectors of the Chingaza NNP, 10 transects were installed with circular plots in each. These were visited twice; in each visit, we collected all deer pellet groups, measuring each pellet to estimate its volume. Population density was calculated using the Eberhardt and Van Etten method and the semi-automated PELLET procedure using FSC and FAR techniques; the age structure was estimated by k-means and fuzzy clustering analyses. With the FAR technique, the estimated deer density was 2.09 ind/km2 in Monterredondo and 0.94 ind/km2 in La Paila. With PELLET, these values were 0.37 ± 0.4 ind/km2 for Monterredondo and 0.16 ± 0.2 ind/km2 for La Paila. The proportion of age classes (adult, juvenile, and fawn) was 1:0.29:0 for Monterredondo and 1:0.57:0.04 for La Paila. The population density of white-tailed deer in two sectors of the Chingaza NNP is not homogeneous, but shows temporal and spatial variations. Population density has decreased versus reports from previous studies in this same area, with the highest deer abundance recorded in 2004, mostly in the Monterredondo sector. The proportion of age classes suggests that the population is stable, as the largest proportion of individuals corresponds to the adult stage

Specialist carabids in mixed montane forests are positively associated with biodiversity-oriented forestry and abundance of roe deer

The ongoing transition within forest management towards more biodiversity-oriented practices, such as close-to-nature forestry and retention forestry, may benefit forest fauna such as forest-specialized ground beetles (Coleoptera: Carabidae). However, it remains unclear how forest carabids are jointly affected by these practices in Central European montane forests, which host particularly sensitive, range-restricted carabid species, and where biodiversity-oriented forestry is widely applied. Moreover, roe deer (Capreolus capreolus), the most common large herbivore in these forests, is intensively managed to reduce browsing pressure, but it is yet unknown how this may affect carabids, alongside the effect of silviculture. On 66 1-ha plots in the Black Forest region of Germany, we sampled carabids with pitfall traps, measured roe deer abundances using camera trapping, and measured several structural variables directly related to close-to-nature and retention practices, as well as variables describing microclimate and landscape-level forest cover. We found that the carabid assemblage was dominated by forest specialists, with little influence from fragmentation of the surrounding forest. Higher broadleaf share (and canopy cover for montane specialists) was correlated with higher carabid activity-density. Increasing stand maturity (and lying deadwood volume for montane specialists), was correlated with higher species richness. Plots with higher roe deer abundances showed higher carabid richness and activity-density. Assemblage composition changed along the altitudinal gradient, and both richness and activity-density increased with elevation. Thus, carabid communities, including montane specialists and several species of conservation interest, stand to benefit from close-to-nature and retention practices, if applied throughout the altitude range of montane forests. Forest carabids may additionally profit from maintaining higher roe deer abundances, but further research is needed to understand this causal link, as well as to weigh the costs and benefits of deer culling for forest biodiversity.

Projecting the dynamics of invading deer with pattern‐oriented modelling to support management decision‐making

Abstract Avoiding the undesirable impacts of invasive species requires robustly evaluating the effects of alternative management scenarios. Such evaluations depend on reliable spatio‐temporal projections of changes in the distribution and abundance of the invasive species under different scenarios. However, commonly used modelling approaches are constrained for this purpose because they do not incorporate demographic processes and are seldom validated. We develop a spatially and temporally explicit grid‐based population model for invasive fallow deer Dama dama in Tasmania, Australia, validated against observed distribution and abundance ‘targets’ using a pattern‐oriented approach. We use this validated model to project the future invasion patterns of deer, including encroachment into areas of high conservation value, under eight harvest and habitat suitability scenarios. Projected population sizes of deer differ greatly depending on harvest and habitat suitability scenarios. Without harvest, the population grows sixfold, from about 80,000 deer in 2019 to over 500,000 by 2100. In contrast, the population stabilises at 32,000–41,000 deer with 25% annual harvest. Abundance in the environmentally sensitive Tasmanian Wilderness World Heritage Area (TWWHA), a region of high conservation value, increases in all scenarios. We identify likely areas in the expanding range of deer where targeted removal should be most effective at minimising deer numbers in the TWWHA. Synthesis and applications: Using a pattern‐oriented model validated with spatio‐temporal data, we show how the future distribution and abundance of invasive fallow deer in Tasmania can be substantially reduced by targeted increases in harvest and prioritising areas for removal around high conservation value regions. Our approach can be used to project likely effects of management interventions on future distributions and abundances for a range of invasive taxa.

Relative abundance of Roe deer (Capreolus pygargus) related to overstory structure and understory food resources in Northeast China

Large herbivores are particularly susceptible to changes in quantity and quality of forage resources, in turn constraining populations of large and threatened carnivores. Key prey species for Amur tigers (Panthera tigris altaica) and leopards (P. pardus orientalis), Siberian roe deer (Capreolus pygargus) have a spatial distribution which is greatly influenced by habitat quality across topographic regions. In this study, we used 138 camera-trap stations to record the abundance and distribution of Siberian roe deer in the mountains (n=88) and valleys (n=50) of the Northeast China Tiger and Leopard National Park, and we examined the impact of overstory structure and understory food resources on the relative abundance index (RAI) of the deer. We use generalized linear mixed models (GLMM) with negative binomial distributions, with the response variable of RAI of either of deer on the mountain or in the valley. We included canopy cover (CC), tree richness (TR) and basal area (BA) from overstory structure and mass of shrub layer (SM), mass of grasses and sedges (GM), forbs mass (FoM), ferns mass (FeM) and understory mass (UM) from understory food as fixed effects. We found that RAI of roe deer was significantly higher for the mountain than the valley. For the mountain, BA, TR and FoM were found to have a significant positive effect on roe deer, while CC showed a negative effect. In the valley, BA had a significant positive effect on roe deer, while SM showed a negative effect. Roe deer appeared to trade-off overstory structure with understory food resources, especially BA and FoM, which may lead them to prefer mountains over valleys in the national park. These findings will assist in understanding the distribution of roe deer populations in Northeast China Tiger and Leopard National Park, and may suggest more effective conservation and management strategies for the forest ecosystems of Northeast China.

Surveillance of ticks on a tropical island with introduced ungulates.

The abundance of hard ticks can be determined by abiotic factors and the presence of suitable hosts. Since deer represent important hosts for many tick species, it is imperative to investigate whether deer introduction will increase the number of ticks, which can transmit a wide variety of pathogens. The sika deer (Cervus nippon) was introduced to Green Island, Taiwan, to supply velvet antlers, a traditional Chinese medicine. However, they were later released into the wild after a steep decline in antler prices. We conducted surveys for questing ticks, ticks on rodents and shrews, and the fecal pellet groups of ungulates (deer and goats) in 31 transects within 3 habitat types (forest, grassland, and roadside) on Green Island every 2 months in 2019. A total of 5,321 questing ticks were collected. All collected ticks were Haemaphysalis mageshimaensis Saito and Hoogstraal, a species first identified on an island with an abundance of sika deer. Additionally, 48 ticks collected from 126 trapped rodents and shrews were almost invariably Ixodes granulatus (except for 1 larval Haemaphysalis sp.). We did not find a positive correlation between the number of questing ticks and the number of fecal pellet groups, suggesting that factors other than ungulate abundance affect tick abundance. Nevertheless, large populations of questing ticks along some roadsides suggest a high risk of tick-borne diseases to tourists on this tropical island.

Factors influencing abundance of 3 tick species across a gradient of urban development intensity in the US Great Plains.

Urbanization alters abiotic conditions, vegetation, and wildlife populations in ways that affect tick abundance and tick-borne disease prevalence. Likely due to such changes, tick abundance has increased in many US urban areas. Despite growing public health importance of tick-borne diseases, little is known about how ticks are influenced by urbanization in North America, especially in the central United States where several pathogens occur at or near their highest incidences. To identify factors influencing tick abundance across a gradient of urbanization intensity, we used CO2 traps and flagging to sample ticks at 16 parks across Oklahoma City, Oklahoma, USA over 2 yr, conducted vegetation surveys, and used trail cameras to estimate a deer abundance index. Our results indicate there is a risk of encountering ticks across the entire urbanization gradient from exurban areas to the urban core, although some species (Dermacentor variabilis (Say)) appear less-common in heavily-urbanized areas. Vegetation variables were also associated with tick abundance. For example, Amblyomma maculatum Koch decreased with increasing woody plant and leaf litter cover, and there was a weak positive relationship between D. variabilis abundance and cover of understory eastern redcedar (Juniperus virginiana L.), indicating this native encroaching tree may increase tick populations in urban areas of the Great Plains. The deer abundance index was positively correlated with A. maculatum and D. variabilis abundance but unrelated to A. americanum (L.) abundance. Public health officials and land managers can use such information about parks/greenspaces and their surroundings to focus public education and land management efforts designed to reduce tick-borne disease prevalence.

A Before‐After Control‐Impact experiment reveals that culling reduces the impacts of invasive deer on endangered peatlands

Abstract Invasive deer have undesirable impacts on native ecosystems. Culling is commonly used to reduce those impacts, but is expensive and sometimes controversial. It is therefore important to robustly assess how culling reduces the impacts of invasive deer. We conducted a Before‐After Control‐Impact (BACI) experiment to determine how culling affects the impacts of invasive sambar deer Cervus unicolor in an endangered alpine peatland ecosystem in south‐eastern Australia. We established two blocks, each with four 4300‐ha experimental units, in which two units were randomly assigned to a treatment of deer culling and the other two were non‐treatment areas. Sambar deer relative abundance (faecal pellet count) and three impacts (ground degradation, pugging intensity and water turbidity) in three peatland features (peatlands, natural pools and sambar deer wallows) were surveyed before and after culling was implemented. We used four metrics to quantify the culling intensity in each treatment unit: treatment versus non‐treatment, number of deer culled on each unit, deer culled within a 500‐m buffer of impact monitoring sites and local probability of use by the cullers (1‐ha grid). The effects of culling on deer abundance and impacts were estimated using Bayesian generalised linear mixed models. Our analysis revealed that the effect of culling differed between the two experimental blocks. In one block, culling reduced deer abundance and three impacts. In the other block, culling did not reduce deer abundance but reduced three impacts and increased two impacts. The effects of culling were generally stronger when culling was estimated using finer‐scale (500‐m) than coarser‐scale (experimental unit) culling metrics. Synthesis and applications. Our study provides experimental evidence that culling invasive sambar deer reduces some of their undesirable impacts on endangered peatlands. That not all impacts were reduced by culling suggests that some effects of invasive species are slow to recover or require higher culling intensities to be reversed.