Overabundant Deer Populations Research Articles

The long‐term drive count and culling data of the sika deer (Cervus nippon) population introduced on Nakanoshima Island in Lake Toya, Hokkaido, Japan, during 1980–2023

AbstractCervid populations introduced to favorable habitats in confinement often increase excessively without predators and hunting. Overabundant deer populations impact the ecosystems and may cause damages to agriculture and forestry. Long‐term count data on the changes in a deer population is essential to understand the relationship between the population dynamics and the natural vegetation. The introduced sika deer (Cervus nippon Temminck, 1836) population without predators on Nakanoshima Island, Hokkaido, Japan, showed repeated irruptions and declines with mass mortality and irregular culling between 1980s and 2000s. The overabundant deer significantly altered the natural vegetation, and density‐dependent changes in population parameters such as body size and reproduction were observed. Here, we present the drive count and culling data to examine the population dynamics during 1980–2023. Deer were counted by 20–30 walking drivers and 2–3 observers on boats once per year in February or March. The number of counted deer rapidly increased from the original three introduced around 1960 to >270 deer (the first peak) in two decades and decreased by half due to starvation and the first culling. Thereafter, the number of counted deer continued to increase with a lower growth rate, reached a higher peak (>400, the second peak) than the first irruption in two decades, and decreased again by half due to starvation and the second culling. Although the number of counted deer increased again up to >300 in several years, it decreased and was maintained at around 100 deer with the annual culling program since 2012. The complete data set for this abstract published in the Data Article section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2024-06.1/jalter-en.

Leaf trait variability explains how plant community composition changes under the intense pressure of deer herbivory

AbstractThere is growing evidence indicating that intraspecific trait variation (ITV) plays a prominent role in determining plant community composition. In this study, we investigated the significance of ITV in identifying the processes that shape the development of forest understory plant communities in an area in which excessive herbivory by overabundant deer populations has been an issue. We measured functional traits (height, leaf area, leaf mass per area, leaf dry matter content, and leaf toughness) of 13 forest floor plant species growing in two contrasting sites in which deer were overabundant or had been completely excluded, respectively, and examined the relationships between species dominance and interspecific trait variation and ITV. We detected variations in the trait plasticity of size and morphological features among species, reflecting species‐specific strategies in response to herbivory and consequently observed marked differences in species composition and diversity at the two sites. Notably, small stature and less costly leaves were identified as important traits that enable plants to persist under conditions of intense deer herbivory probably because such plants are less exposed to herbivory and simultaneously optimize carbon assimilation. In contrast, large‐sized plants with costly leaves tended to dominate the plant community in the absence of deer herbivory, as these plants would tend to gain a competitive advantage with respect to the acquisition of space and light. The findings of this study indicate that a focus on ITV represents a promising approach for determining the general ecological patterns of plant communities responding to environmental disturbance.

Long-term effects of white-tailed deer overabundance, hybrid poplar genotype and planting stock type on tree growth and ecosystem services provision in bioenergy buffers

Populus hybrids are increasingly planted in multifunctional bioenergy buffers bordering crop fields. However, such small agroforestry systems are vulnerable to damage caused by overabundant deer populations. We measured after 8 years the effects of white-tailed deer (Odocoileus virginianus), genotype and planting stock type on tree growth and ecosystem services provision (biomass production; energy, nutrient and carbon storage; and phytoaccumulation of soil nitrate and phosphorus) in 15-m wide buffers located downslopes of hayfields in southern Québec (Canada). Two deer protection treatments (fenced and unfenced), two genotypes (P. deltoides × P. nigra, genotype D×N-3570 and P. maximowiczii × P. balsamifera, genotype M×B-915311) and two stock types (bare-root stocks: ±1.8 m in height and whips: 2.5 m in height) were studied. In unfenced plots, deer heavily browsed poplars (increase in the height of the first branch by 59 cm), repeatedly rubbed tree bark (36% of trees with rubs for genotype D×N-3570, and 59% for genotype M×B-915311), slightly decreased survival (by 2.9%), which reduced tree-level and stand-level productivity. Proportion of trees with rubs, first branch height and survival were correlated (p < 0.001) with woody biomass yields. Fenced poplars increased wood volume, biomass and energetic content by 20–21%, and C, N and P stocks in aboveground biomass by 13–20%. Higher soil phosphorus bioavailability was also found in unfenced plots. Genotype D×N-3570, which allocates less biomass to branches, grows its first branches farther from the ground and rapidly develops a rough and thick bark, was the least affected by deer, despite its high palatability. Genotype M×B-915311, which had higher biomass allocation to branches, a smooth and thin bark, but low palatability, was the most affected by deer. Soils in plots of genotype M×B-915311 had the lowest macronutrients availability, except for nitrate. Biomass feedstock quality (i.e. low nutrient concentrations and high heating value of woody biomass) was highest for genotype M×B-915311. In both fenced and unfenced plots, whips were more productive than bare-root stocks, especially for genotype D×N-3570. Optimizing ecosystem services provision in bioenergy buffers can be achieved by fencing, and by genotype and stock type selection.

Interspecific competitive potential of wavyleaf basketgrass (Oplismenus undulatifolius), a recent introduction to the mid-Atlantic United States

AbstractUnderstanding the mechanisms by which an invasive plant species is able to colonize and successfully expand into native plant communities can help in estimating the potential threat posed by a new invader and predict impacts on community diversity, structure, and function. Wavyleaf basketgrass [Oplismenus undulatifolius (Ard.) P. Beauv.] is a perennial, shade-tolerant grass species that has been recently introduced to the mid-Atlantic United States. Areas invaded by O. undulatifolius typically have low species richness, but it is unknown whether O. undulatifoius actively outcompetes other species or simply thrives primarily in species-poor habitats. This study used a greenhouse experiment to quantify interspecific competition in shade and sun among seedlings of O. undulatifolius; Japanese stiltgrass [Microstegium vimineum (Trin.) A. Camus], an invasive annual grass common in the region; and a mix of three native perennial grass species commonly used in restoring areas invaded by M. vimineum. In this experiment, shade did not significantly affect growth or competitive ability. Interspecific competition irrespective of shade had a negative effect on growth of all species, but O. undulatifolius was affected to a much greater degree than either M. vimineum or the native grass mix. These results suggest that, at least under these conditions, O. undulatifolius is a weak interspecific competitor and may be capable of forming dense monotypic stands only in areas that already have low species diversity. In the mid-Atlantic region, postagricultural legacies and overabundant deer populations, which lead to depauperate understories, may be a major facilitator of O. undulatifolius invasion in forests.

White-Tailed Deer in Tallgrass Prairie: Novel Densities of a Native Herbivore in Managed Ecosystems

White-tailed deer (Odocoileus virginianus) are now the dominant large herbivores in tallgrass prairie ecosystems of the U.S. Midwest and have unique ecological impacts compared to the historically dominant bison (Bison bison) and elk (Cervus elaphus) that were extirpated from this region. While most of our knowledge of white-tailed deer impacts on plant communities and ecosystem processes comes from forested habitats, relatively little research has focused on deer effects in prairies. In this review, we discuss the ecological impacts of white-tailed deer in North American tallgrass prairies, potential deer management strategies, and areas of future research.Unlike bison and elk, deer are selective grazers that preferentially eat nutrient-rich forbs. At high deer densities, this consumption of forbs can have negative effects on prairie biodiversity and alter nutrient cycling. Deer can decrease plant diversity by reducing the abundance and reproductive success of their preferred plant species, shifting the plant community to one dominated by species avoided by deer or tolerant of herbivory.At lower densities, deer may maintain biodiversity in accordance with the intermediate disturbance hypothesis. Deer are able to maintain a balance between deer-avoided and deer-preferred species abundance by giving unpreferred or herbivory-tolerant species an advantage, but not completely suppressing herbivory-sensitive species. Nonconsumptive deer impacts also influence prairies through transporting invasive species, trampling on deer trails, and redistributing nutrients in fecal pellets and carcasses. Management strategies such as hunting, use of fences, and patch-burning can alleviate the pressures of overabundant deer populations, while maintaining their ability to promote heterogeneity.

Effects of sika deer (Cervus nippon) and dwarf bamboo (Sasa senanensis) on tree seedlings in a cool-temperate mixed forest on Hokkaido Island, Japan

Overabundant deer populations have direct and indirect effects on forest vegetation. For forest regeneration, it is important to identify the response of tree seedlings to deer browsing following a reduction in deer density. We examined the effects of deer density, dwarf bamboo coverage, light availability, and tree species on seedling survival and growth inside and outside deer-excluding fences, from 2009 to 2011 in a cool-temperate mixed forest on Hokkaido Island, Japan. The occurrence probability of browsing was high in the plots with high pellet density. Bamboo coverage decreased significantly with increased pellet density. The survival rate of seedlings was negatively affected by both the occurrence of browsing and bamboo coverage. The growth of seedlings was negatively affected by the occurrence of browsing. Our study showed that deer browsing had both a direct negative effect by decreasing seedling survival and an indirect positive effect by reducing bamboo coverage. These results suggest that we should examine browsing intensity and the response of forest vegetation and recognize the competitive and facilitative effects of neighbouring plants on tree seedlings.

The importance of intrinsic traits, environment and human activities in modulating stress levels in a wild ungulate

Identifying the ecological and anthropogenic processes that affect wildlife physiology, and that may operate as chronic stressors, is of prime importance to implementing appropriate management and conservation strategies. Although advances have been made in understanding the physiological ecology of wild ungulates, little is known of how multiple intrinsic and ecological factors work, either independently or synergistically, to modulate their stress responses. By using faecal glucocorticoid metabolites (FGM) as indicators of stress, a set of environmental and human determinants affecting the stress physiology of wild red deer (Cervus elaphus) was examined in the Mediterranean ecosystems of south-western Europe, where this species is subjected to contrasting weather regimes and hunting management systems. Variation-partitioning techniques were also used to estimate the comparative influence of factors related to an individual’s intrinsic characteristics, environmental conditions and management practices in shaping physiological stress levels. Our results showed that factors related to hunting management were the main drivers of FGM variation in red deer, followed by those related to the environmental conditions and individuals’ traits, and their effects were closely associated to spatio-temporal variability. Holding massive hunting events involving the use of hounds, as well as high population densities, were related to more long-term stress levels in the populations studied. Evidence was also found that supplementary feeding practices may mitigate the negative effects of reduced food availability in overabundant deer populations. Weather conditions were also significant factors explaining variation in stress levels; accumulated rainfall and an increase in ambient temperatures during the coldest months were associated with a decrease in stress hormone levels. No differences in hormonal concentrations were found between males and females, but higher levels of hormone metabolites were detected in younger animals in both sexes. Our findings provide an integrated perspective of how multiple factors impact on stress physiology in large wild herbivores and highlight the importance of considering management practices, as well as spatio-temporal variation, when assessing stress-inducing factors in wild populations. Given the implications of this study regarding the impact of human activities on physiological stress levels in wild animals, it could be an important basis to support wildlife management decisions.

Drivers of population growth variations for two Mediterranean sympatric Deer

AbstractDetecting density‐dependence (DD) in population fluctuations is essential for population control, herd management and harvest programs. However, little information has been obtained for deer in Mediterranean ecosystems. We assess the effects of density, climate and harvesting on population growth fluctuations of two sympatric red (Cervus elaphus hispanicus) and fallow deer (Dama dama), in two hunting reserves located in a protected area of south‐east Spain. We use time series analysis of 16 consecutive years of abundance estimates and hunting extractions. We hypothesized a negative influence of density, deer hunting and drought on population growth rates. Through an integrative Bayesian state‐space modeling making possible a unified population analysis we have been able to not only estimate the effects of DD, climate and harvest extractions but also to evaluate their relative impacts on deer population in each location. We found deer populations exhibiting a very strong potential to grow from low density. We detected DD having a stronger effect than hunting and climatic factors, especially for overabundant deer populations close to their carrying capacity. Density‐dependent mechanisms compensate harvest extractions, reducing hunting effectiveness. Severe summer drought conditions had negative effects on growth rates and eventually led to delayed autumn deer deaths. The weather effect is more important the more abundant the deer are. In a climate change context, in Mediterranean environments the importance of weather factors could become much greater if both ungulates’ densities and aridity increase. Population size control here could modulate the negative effects of climatic constraints on deer and ecosystems conservation.

Initial site conditions and interactions between multiple drivers determine herb-layer changes over five decades in temperate forests

The resurvey of forest plant communities some decades after the first survey has become a valued approach to determine long-term responses in species diversity and composition to various anthropogenic environmental drivers, such as management changes, excess nitrogen deposition, or overabundant deer populations. However, little is known about the effects of initial site conditions, such as soil acidity or soil moisture, on these long-term responses and how multiple drivers interact with each other in affecting herb layer diversity and composition. Moreover, the extent to which local changes in canopy cover and composition may mimic or counterbalance effects of regional or global drivers is largely unexplored. Here, we resurveyed herb layer vegetation plots in northeastern Germany after more than five decades. Our main objectives were (1) to determine the effects of initial site conditions, here soil pH buffer range, on herb layer and environmental changes; (2) to disentangle the effects of presumed regional and global drivers from local changes in canopy density and composition; and (3) to identify interactions between environmental drivers in affecting species diversity and composition. We observed significant changes in species diversity and environmental conditions, mostly in dependence on the initial site conditions. Species richness increased only at moderately acidic to base-rich sites, while floristic distinctiveness (beta diversity) generally decreased but decreased significantly stronger on base-rich than on acidic sites. The indicated environmental changes comprised increased shading (particularly on acidic sites), a decrease in soil moisture, acidification (only on initially moderately acidic to base-rich sites), eutrophication (only on acidic sites), an increase in browsing pressure and more continental climatic conditions, probably in terms of increased summer drought (on well-drained sites only). The presumed regional/global environmental changes could not be explained by local changes in canopy composition. The herb layer responses were affected by several important interactions among the drivers. The floristic homogenization was more pronounced the stronger the eutrophication signal, but only on (moderately) acidic sites, while the homogenization occurred independent of any eutrophication on base-rich sites. The environmental change indicators for soil acidity and nitrogen availability showed opposing effects on temporal species turnover and a positive interaction, pointing to atmospheric deposition as the most important driver. Our study demonstrates that both initial site conditions and interactions between different drivers should be taken into account in resurvey studies to broaden our understanding of plant community responses to environmental changes.

Corrigendum: Short-term effects of hunting on naïve black-tailed deer (Odocoileus hemionus sitkensis): behavioural response and consequences on vegetation growth

Hunting is commonly used to reduce overabundant deer populations that are of socioeconomic and ecological concerns. Recently, it has been suggested that “hunting for fear” might help maximize nonconsumptive effects of hunting and their cascading impacts. We investigated how a predator-free black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898) population introduced to the Haida Gwaii archipelago (Canada) responded to short-term hunting for fear. We conducted a hunt that minimized killing and maximized scaring on an island where some deer were marked. Between control and hunted sites, we compared deer use of bait stations and of shoreline areas (i.e., an open and risky area that provided marine subsidies). We also compared the browsing pressure and growth of two grasses and two shrubs. Hunting for fear had no effect on the overall use of bait stations and shorelines. However, in the area exposed to hunting, unmarked deer, which were assumed to be less tolerant of human disturbance, avoided bait st...

Short-term effects of hunting on naïve black-tailed deer (Odocoileus hemionus sitkensis): behavioural response and consequences on vegetation growth

Hunting is commonly used to reduce overabundant deer populations that are of socioeconomic and ecological concerns. Recently, it has been suggested that “hunting for fear” might help maximize nonconsumptive effects of hunting and their cascading impacts. We investigated how a predator-free black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898) population introduced to the Haida Gwaii archipelago (Canada) responded to short-term hunting for fear. We conducted a hunt that minimized killing and maximized scaring on an island where some deer were marked. Between control and hunted sites, we compared deer use of bait stations and of shoreline areas (i.e., an open and risky area that provided marine subsidies). We also compared the browsing pressure and growth of two grasses and two shrubs. Hunting for fear had no effect on the overall use of bait stations and shorelines. However, in the area exposed to hunting, unmarked deer, which were assumed to be less tolerant of human disturbance, avoided bait stations at the outset of hunting. We concluded that individuals perceive and respond to risk differently. Furthermore, two of the four plant species were less likely to be browsed and had better growth in the experimental area than in the control area, suggesting an indirect effect of hunting on plants mediated by deer behaviour.

Herbaceous layer response to 17 years of controlled deer hunting in forested natural areas

Deleterious effects of overabundant deer populations within natural areas have been well documented and hunting programs have been initiated to control populations and facilitate the recovery of vegetation communities. However, few studies have examined whether recovery has occurred following sustained hunting. Hunting was initiated during the 1990s to reduce overabundant deer populations in Indiana state parks. In 2010, we resampled 108 plots established in 1996/97 across 15 state parks and five historically-hunted reference areas to quantify changes in herbaceous-layer vegetation. Species cover was measured along three, 10m line transects nested within each plot. Data were pooled for all parks and reference areas. We calculated species richness (S), evenness (E), and Shannon-Weiner diversity (H′) in 1996/97 and 2010. Compositional changes between sample intervals and contemporary composition across environmental gradients were examined using nonmetric multidimensional scaling (NMS). We observed greater increases in herbaceous-layer cover in parks than in reference areas. S and H′ increased significantly in parks, but not reference areas. NMS ordinations revealed unidirectional changes in species composition between parks and their respective reference areas with the composition of parks becoming more similar to that of reference areas through time. Park size, cumulative deer harvest, initial deer abundance, and recent average of harvest/hunter effort were significantly correlated (p<0.05) with ordination scores in four out of five natural regions (|r|>0.5 for at least one axis). Browse-sensitive functional groups increased in cover while that of exotic species decreased. Changes were most pronounced for tree seedlings, which displayed a sixfold increase in cover within parks between sample intervals. These results suggest that hunting has allowed recovery of degraded vegetation communities.

Deer overabundance in the USA: recent advances in population control

During the 20th century, deer (Odocoileus spp.) populations in many parts of the USA changed from locally extirpated to locally overabundant. In 1997, two comprehensive books were published on deer overabundance to help wildlife professionals understand the complex biological, ecological, sociopolitical, public, and legal issues associated with managing overabundant deer. Since then, there have been several advances in dealing with deer overabundance, which have been briefly summarised in this review article. Most notably, since 1997 ecologists have more definitively characterised the ecological consequences of chronically overabundant deer populations, not merely in terms of direct impacts on plant communities but also in terms of cascading effects on animal communities. While still acknowledging the complexity of the interactions that affect ecosystem services and states (e.g. top-down pathways, bottom-up forces, disturbance regimes), ecologists now believe that the presence of an apex predator can affect the density, as well as behaviour and physiology of ungulates, and thereby help maintain the natural structure and functioning of plant communities. In some situations, wildlife researchers in the USA have restored native predators or documented adaptive responses by colonising predators, both of which have helped reduce locally overabundant deer populations and helped restore plant community diversity. On the wildlife policy front, some state wildlife agencies have enacted new programs to manage overabundant deer in protected areas and in urban and suburban settings. Examples include special permits for lethal removal of urban deer, as well as public hunts using special weapons (e.g. crossbows) or sharpshooting programs to control deer in state parks. A better understanding of the human dimensions associated with deer overabundance has helped many agencies define appropriate public education programs. However, despite these efforts to educate stakeholders about deer overabundance, there have been legal challenges associated with programs designed to control deer populations in some suburban communities. Some nongovernmental organisations (NGOs) have implemented award-winning, classroom-based educational modules to help children learn how to live with deer. Some NGOs also have stressed the importance of hunting as an ecological service. Still other NGOs have worked to facilitate linkages and cover liability concerns to enable bowhunters to help control deer in suburban communities. There also have been major advances in the potential for managing overabundant deer with fertility control, including the recent approval of an immunocontraceptive vaccine for use in deer (GonaCon™). In summary, wildlife biologists now understand the complex issues associated with deer overabundance better and there are more ‘tools in the chest’, both in terms of agency policies and management procedures than in 1997. Yet, human dimensions, public education, and stakeholder concerns continue to be the most challenging aspects of managing deer overabundance. Therefore, this issue likely will continue to confront wildlife professionals for many decades to come, whether in the USA or other parts of the world.

White-tailed deer attacking humans during the fawning season: a unique human–wildlife conflict on a university campus

Human-wildlife confl icts associated with suburban white-tailed deer (Odocoileus virginianus) populations have increased in the last 20 years. Primary threats to human health and safety associated with overabundant deer populations include deer-vehicle collisions, attacks on humans, disease, and damage to native and ornamental vegetation. During the fawning seasons (May-June) of 2005 and 2006, 13 confi rmed incidences of white-tailed deer attacking humans occurred on the campus of Southern Illinois University-Carbondale. To our knowledge, no report exists that documents free-ranging does attacking humans during the fawning season. The attacks occurred at multiple locations on campus, with injuries to humans, including minor scrapes, bruises, broken bones, and skin lacerations requiring stitches. Wildlife managers may face the increased likelihood of aggressive behavior from deer directed towards humans as deer and human populations increase and come into closer contact with each other.

Field test of a single-injection gonadotrophin-releasing hormone immunocontraceptive vaccine in female white-tailed deer

The development and use of safe, effective and practical wildlife contraceptive agents could reduce reproduction in locally overabundant deer populations in situations where traditional management tools such as regulated hunting cannot be employed. GonaCon Immunocontraceptive Vaccine (the commercial name for a particular gonadotrophin-releasing hormone (GnRH)-based emulsion) was tested in adult female white-tailed deer in a fenced herd near Silver Spring, Maryland, USA. Observations of udder condition were used to identify does that had become pregnant. Necropsy observations, histopathology and serum concentrations of anti-GnRH antibodies, luteinising hormone and progesterone were used to compare health and reproductive status of treated (n = 28) and control (n = 15) deer. After receiving one injection of GonaCon, 88% of treated deer did not become pregnant during the first year and 47% did not become pregnant during the second year after vaccination. No adverse health effects related to vaccination with GonaCon were detected, except for localised injection-site reactions in five (29%) of 17 examined, vaccinated deer. Treatment with GonaCon can be a safe and effective means of inducing temporary infertility in wild white-tailed deer. Ultimately, the management value of GonaCon will be determined by natural-resource professionals who use it as one of many tools to manage deer populations.

Acceptance of Deer Management Strategies by Suburban Homeowners and Bowhunters

Abstract: More communities are experiencing problems associated with overabundant white‐tailed deer (Odocoileus virginianus) populations. Public acceptance of approaches for managing deer may differ within communities. Although hunting with firearms is a common practice used to manage deer populations, many suburban communities only allow bowhunting. Our objectives were to assess suburban homeowners and bowhunters acceptance of lethal and nonlethal deer management strategies. Additionally, we wanted to determine homeowner willingness to pay for deer management and how long they would be willing to wait for relief to address conflicts caused by deer overabundance. Most homeowners supported using lethal strategies to reduce and manage deer populations. Most homeowners were unaware of the cost (94%) or effectiveness (92%) of birth control agents to manage free‐ranging deer populations. Of lethal strategies, bowhunting was preferred. Establishment of a special crossbow season outside the existing archery season received the greatest support by bowhunters and was also acceptable to homeowners. As landscapes progressed from rural to more urban, hunting access, human‐wildlife conflicts, and homeowner willingness to pay for deer management decreased. Regardless of management strategy, most homeowners were willing to wait 3‐5 years to achieve a desired reduction in the deer population at no cost to them. As costs increased, homeowner willingness to wait decreased. Because exposure, tolerance of deer, and willingness to pay for management varies by landscapes, towns with diverse landscapes should consider developing regional rather than town‐wide plans to manage overabundant deer populations.

Green and Blue Lasers are Ineffective for Dispersing Deer at Night

Abstract Over-abundant populations of white-tailed deer (Odocoileus virginianus) create agricultural and human health and safety issues. The increased economic damage associated with locally overabundant deer populations accentuates the need for efficient techniques to mitigate the losses. Although red lasers can be an efficient tool for reducing damage caused by birds, they are not effective for deer because deer cannot detect wavelengths in the red portion of the spectrum. No research has been conducted to determine if lasers of lower wavelengths could function as frightening devices for deer. We evaluated a green laser (534 nm, 120 mW) and 2 models of blue lasers (473 nm, 5 mW and 15 mW) to determine their efficacy in dispersing deer at night. Deer were no more likely to flee during a green or blue laser encounter than during control encounters. The green and blue lasers we tested did not frighten deer.

Vegetative Legacy of a Protected Deer Herd in Cades Cove, Great Smoky Mountains National Park

Overabundant deer populations pose significant challenges to the conservation of native plant communities. We examined the effects of a protected white-tailed deer (Odocoileus virginianus Zimm.) population on forest plant communities in Cades Cove, Great Smoky Mountains National Park. The Cove deer herd reached 43 deer km−2 at its peak in the late 1970s. While current densities are somewhat lower, the diversity and coverage of many understory species remains greatly reduced. To elucidate the influence of contemporary deer browsing, an exclosure study was established in 1997. Ten 10-m × 10- m sample plots were randomly located at three sites, half of which per site were exclosed. Understory vegetation on all 30 plots was intensively sampled in August 2004. While the diversity and richness of herbaceous species was similar in exclosures and controls following eight years of deer exclusion, exclosures contained significantly more diverse sapling layers (tree species ≤2 m in height). Correspondingly, exclosures contained significantly greater sapling densities than control plots (P < 0.001). Herbaceous and sapling layer composition varied between exclosures and controls. Forbs, vines, and low woody shrubs were consistently more abundant within exclosures than control plots. Graminoids (both native and exotic) dominated both exclosures and controls, but typically had greater relative abundance on control plots. Given the modest recovery of the herbaceous layer and the persistence of non-preferred browse species following eight years of deer exclusion, plant community recovery would be slow and uncertain even if the density of deer within the Cove was reduced.

Assessing strategies to improve bowhunting as an urban deer management tool

Firearms hunting often is limited as a deer (Odocoileus spp.) management tool in urban and suburban areas due to firearms discharge ordinances, restrictive hunting laws, or public perception about firearms safety. Many states use bowhunters to manage overabundant deer populations in urban-suburban areas. Little information exists on the effectiveness of bowhunting as a deer management tool in developed areas. Our objectives were to evaluate the potential for bowhunting to manage deer populations in urban-suburban areas and identify important variables influencing hunt effectiveness. We estimated deer population size and herd composition using aerial deer surveys and spotlight counts. Nonhunting mortality was determined from radiotelemetry data. We mailed a 9-page survey to bowhunters who hunted in a residential community with high deer densities to determine harvest rates, hunter success rates, willingness to harvest additional antlerless deer, and interest in employing aggressive deer management strategies. Of 159 surveys mailed, 71% were completed and returned. We conducted model simulations using Program STELLA® (High Performance Systems Inc., Lebanon, N.H.) to determine which management strategies would contribute most to stabilizing deer population growth. Sunday hunting provided 41% fewer hunting days, yet was more effective at reducing deer population growth than a January extension. Harvesting antlerless deer that hunters were passing up had the greatest relative effect in reducing deer population size. Incentive programs for hunters to harvest antlerless deer are needed. Combining multiple hunt strategies (i.e., January and Sunday hunting) may be more effective than implementing individual hunt strategies. A special crossbow season outside the existing archery season may be an effective deer management tool in urban areas.

Effort and the Functional Response of Deer Hunters

Managers of overabundant deer have failed to incorporate relevant predator-prey theory into management research. In particular, understanding the functional response of deer hunters (deer encountered/time) to declining deer density is important because functional responses determine relative effort (time/deer encountered) required to harvest a deer and may, in turn, influence hunter perceptions of deer density and costs associated with deer removal. We used information-theoretic techniques and nonlinear regression to reanalyze data from controlled hunts in Illinois, Michigan, Wisconsin, and Ontario. Alternate models include killing rates or sighting rates as Type 1 (linear), Type 2 (hyperbolic), or Type 3 (sigmoidal) functions of deer density. Akaike's information criteria suggested that optimal models for most data sets were Type 1, although this may have been a artifact of small sample sizes. Nonetheless, effort curves derived from fitted functional responses indicated that relative effort accelerates as deer density declines. Accelerating effort requirements on the part of deer hunters likely hinders agency efforts to reduce overabundant deer populations and may be a source of hunter perceptions of unrealistically reduced deer herds. If general, this relation-ship (1) may determine what levels of harvest/removal are realistic, (2) is a potential source of bias in population estimation, and (3) may contribute to hunter distrust of agency efforts to reduce population size.