Increase In Deer Populations Research Articles

Anthropogenic disturbances alter responses of understory plants to deer density: A 9-year deer density control experiment

The increasing deer population and their expanding distribution have altered the diversity and biomass of the plant community in the northern hemisphere. Furthermore, anthropogenic disturbances such as nitrogen deposition and logging threaten plant diversity in many parts of the forests. Therefore, it is necessary to investigate the effects of deer on plant communities under nitrogen deposition and logging conditions to understand and conserve plant diversity in forest ecosystems. We conducted a field experiment that controlled three levels of deer densities (exclosure: 0 deer/km2, low: 10 deer/km2, and high: 20 deer/km2) and four anthropogenic disturbances (without anthropogenic disturbances [control], nitrogen addition, logging, and nitrogen addition and logging combined) in a cool temperate secondary forest in northern Japan for nine years. We surveyed the effects of deer density and anthropogenic disturbance treatments on species richness and vegetation cover of life forms (forbs, ferns, trees, graminoids, unpalatable species, vines, and shrubs) and all species of understory vascular plants. We estimated the constant effect (without the elapsed year) and the temporary effect (with the elapsed year) of deer density, anthropogenic disturbances, and their interactions on the species richness, vegetation cover, and Simpson’s index as separate parameters in full models and selected the best model. The high deer density negatively affected the species richness of some life forms and all species and accelerated these effects over time for all species. The vegetation covers of most of the life forms were negatively affected by high deer density, and the effect was reduced over time. In contrast, the exclosure negatively affected the species richness of some life forms and positively affected the vegetation cover of most of the life forms and all species. The effect on the cover accelerated over time. Nitrogen addition accelerated the negative effect of high deer density on the species richness of shrubs. On the other hand, logging reduced the negative effect of high deer density on the species richness of all species. The cover of unpalatable species in the high deer density site with logging was approximately nine times higher than that in the high deer density site without anthropogenic disturbances in the last surveyed year. The high deer density and logging decreased the Simpson’s diversity index score. These results indicate that the effects of deer density, anthropogenic disturbances, and their interactions vary with time. These interactions must be considered to manage deer’s effect on forest ecosystems.

Possible expansion of Ixodes ricinus in the United Kingdom identified through the Tick Surveillance Scheme between 2013 and 2020.

The tick Ixodes ricinus (Ixodida: Ixodidae, Linnaeus) is the main vector of several pathogens including Borrelia burgdorferi s.l. (agent of Lyme borreliosis) and tick-borne encephalitis virus. Its distribution depends on many factors including suitable habitat, climate and presence of hosts. In this study, we present records of I. ricinus bites on humans, dogs (Canis lupus familiaris; Carnivora: Canidae, L.) and cats (Felis catus; Carnivora: Felidiae, L.) in the United Kingdom (UK) obtained through the Tick Surveillance Scheme between 2013 and 2020. We divided the UK into 20 km x 20 km grids and 9.2% (range 1.2%-30%) of grids had at least one record every year since 2013. Most regions reported a yearly increase in the percentage of grids reporting I. ricinus since 2013 and the highest changes occurred in the South and East England with 5%-6.7% of new grids reporting I. ricinus bites each year in areas that never reported ticks before. Spatiotemporal analyses suggested that, while all regions recorded I. ricinus in new areas every year, there was a yearly decline in the percentage of new areas covered, except for Scotland. We discuss potential drivers of tick expansion, including reforestation and increase in deer populations.

Diets of Black Vultures and Turkey Vultures in Coastal South Carolina, USA with a Review of Species' Dietary Information

Food availability resulting from anthropogenic land-use changes may have contributed to the recent increase of Cathartes aura (Turkey Vulture) and Coragyps atratus (Black Vulture) populations. We assessed anthropogenic contributions to diets of these species by analyzing 176 pellets collected from communal roosts in coastal South Carolina. To provide further insight into diets, we conducted a literature review of pellet-based studies for both species. Our pellet analyses demonstrated consumption of 12 mammal species with Odocoileus virginianus (White-tailed Deer) as the primary food item, present in 65% of samples and constituting 35% average percent volume in pellets. Mephitis mephitis (Striped Skunk) and Procyon lotor (Raccoon) were also commonly consumed. Presence of anthropogenic items in 47% of pellets indicated substantial garbage consumption. Our review consisted of 14 studies and revealed wide variability in diet across study sites, with large mammals (>15 kg) typically comprising the majority of species consumed. We suggest that increasing deer populations provide an important source of carrion for vultures in this area and likely throughout eastern North America. Ungulate populations, roadkill, and garbage appear to contribute considerably to Turkey Vulture and Black Vulture diets. As such, mitigation of human–vulture conflict will require effective garbage and roadkill management as Turkey Vulture and Black Vulture populations increasingly expand.

Human and environmental associates of local species-specific abundance in a multi-species deer assemblage

Understanding how habitat, landscape context, and human disturbance influence local species-specific deer density provides evidence informing strategic management of increasing deer populations. Across an extensive (187 km2) heterogeneous forest-mosaic landscape in eastern England, spatially explicit density surface models of roe deer Capreolus capreolus and introduced muntjac Muntiacus reevesi were calibrated by thermal imaging distance sampling (recording 1590 and 400 muntjac and roe deer groups, respectively, on 567 km of driven transects). Models related deer density to local habitat composition, recreational intensity, and deer density (roe deer models controlled for muntjac density and vice versa) at a local grain across 1162 composite transect segments, incorporating geographical coordinates accounting for spatial autocorrelation. Abundance of both species was lower in localities with more grasslands (inter-quartile, IQ, effect size: roe −2.9 deer/km2; muntjac −2.9 deer/km2). Roe abundance (mean = 7 deer/km2, SD = 6) was greater in localities with more young stands (IQ effect size, + 1.3 deer/km2) and lower at localities with more recreationists (−1.1 deer/km2). Muntjac density (mean = 21 deer/km2, SD = 10) was greater in localities with more recreationists (+ 2.4 deer/km2), with more mature (≥ 46 years) stands (+ 1.5 deer/km2), or calcareous soil (+ 7.1 deer/km2). Comparison of models incorporating candidate variables and models comprising geographical coordinates only shows candidate variables to be weak predictors of deer densities. Adapting forest management to manipulate habitat and recreational access may influence local deer densities, but only subtly: effect sizes are not sufficient to mitigate deer impacts through planting vulnerable tree crops in areas avoided by deer. Effective culling remains the most viable management option.

Perceptions, concerns, and management of white-tailed deer among municipal officials

ABSTRACT Municipal governments are emerging as important stakeholders in managing the populations and geographic distributions of white-tailed deer (Odocoileus virginianus) in urban and suburban areas of the Northeastern United States. To understand the variation in municipal-level concerns about deer and municipal policies related to deer management, we distributed a questionnaire to all 351 municipalities across the Commonwealth of Massachusetts in 2017 (response rate = 74%) and collected data on local bylaws that influence hunting access. We found that concerns about deer vary across the state and some municipalities are taking action to manage increasing deer populations. In particular, our analysis established the importance of deer and deer management in the suburban regions of Massachusetts, while uncovering many local differences within similar suburban areas. The varying relationships between deer populations, public concerns, and municipal actions illustrated the complex role of municipal decision-makers in shaping wildlife management programs.

Factors affecting deer pressure on forest regeneration: The roles of forest roads, visibility and forage availability.

Deer pressure on forest regeneration constitutes a serious problem in commercial forests in the northern hemisphere due to the increase in deer populations. However, other drivers, such as climate, landscape structure and the level of human activity, have a strong influence on deer pressure. The direct, density-related impacts of ungulates on forest regeneration have been well studied, but there is limited empirical evidence related to the indirect factors mentioned above. We conducted a field experiment in three forest divisions in Poland to evaluate the role of a common element of human infrastructure, i.e. small, unpaved forestry roads. Additionally, we assessed the modifying effect of visibility driven by vegetation cover and forage availability. The proximity of unpaved roads affected deer habitat use and foraging behaviour, and limited browsing pressure on regenerating forests. Low visibility and higher winter forage availability increased the probability of tree browsing. We observed different responses to roads in two deer species: red deer avoided roads, while roe deer browsed in the vicinity of roads. A typical forest network of unpaved roads creates a landscape of fear for red and roe deer, and limits browsing pressure on regenerating forests due to the changes in deer habitat use, activity patterns and foraging behaviour. Knowledge of the factors influencing browsing pressure can help to spatially optimise the application of protective measures for tree seedlings.

Deer slow down litter decomposition by reducing litter quality in a temperate forest

Litter decomposition is a key process that allows the recycling of nutrients within ecosystems. In temperate forests, the role of large herbivores in litter decomposition remains a subject of debate. To address this question, we used two litterbag experiments in a quasiexperimental situation resulting from the introduction of Sitka black-tailed deer Odocoileus hemionus sitkensis on forested islands of Haida Gwaii (Canada). We investigated the two main pathways by which deer could modify litter decomposition: change in litter quality and modification of decomposer communities. We found that deer presence significantly reduced litter mass loss after 1 yr, mainly through a reduction in litter quality. This mass loss reflected a 30 and 28% lower loss of carbon (C) and nitrogen (N), respectively. The presence of deer also reduced the ability of decomposers to break down carbon, but not nitrogen. Indeed, litter placed on an island with deer lost 5% less carbon after 1 yr of decomposition than did litter decomposing on an island without deer. This loss in ability to decompose litter in the presence of deer was outweighed by the differences in mass loss associated with the effect of deer on litter quality. Additional effects of feces deposition by deer on the decomposition process were also significant but minor. These results suggest that the effects dramatic continental-scale increases in deer populations may have on broad-scale patterns of C and N cycling deserve closer attention.

Investigating the factors influencing trap capture of bark and ambrosia beetles using long-term trapping data in a cool temperate forest in central Japan

ABSTRACT From 1994 to 2003, bark and ambrosia beetles were captured from April to November at 12 sites in the University of Tokyo Chichibu Forest, central Japan, using flight-barrier traps with alpha-pinene and ethanol as a lure. Additional trapping was conducted between July 2013 and November 2014 at the same sites using Lindgren’s funnel traps with ethanol. Factors influencing trap captures were investigated, accounting especially for the indirect influence of sika deer on beetle populations due to induced tree mortality. Owing to incomplete data collection in 2013, trap captures of August and after August (“AUG” for 12 years) were analyzed separately from those of the whole season (“ALL” for 11 years). Trap captures in 2013–2014 were greater than those in 1994–2003. There was also an increase in the number of species across both periods, which was more conspicuous in “AUG”. Seventeen indicator species were found in 2013–2014, and only two in 1994–2003. This could be partially explained by the difference in the lure used. A sudden population increase in 25 species was observed between the average over 1994–2003 and 2013–2014. Increasing trends during the 1994–2003 were also recognized in 13 species, with a sudden increase in 6 species in the last few years of the period. These coincided with increases in sika deer populations across both periods. An increase in tree mortality caused by increases in the deer population is likely the cause of the increase in bark and ambrosia beetles.

Factors affecting attitudes toward reintroduction of wolves in Japan

Japanese wolves (Canis lupus hodophilax) became extinct in the early 1900s. Because the country is experiencing growth in populations of ungulates, the potential of reintroducing wolves to promote self-regulating biodiverse ecosystems has been discussed by various Japanese and international researchers. However, limited research exists regarding public attitudes toward the reintroduction of wolves, which is indispensable to the success of such projects. We conducted a survey of 360 undergraduate students at a university in Japan and found that while most respondents believed that government officials and local residents should be responsible for the decision-making, a majority felt that this responsibility should not rest with the general citizens. Multiple regression analysis revealed that respondents disagreed with the reintroduction of exotic species generally, while those who thought wolves are necessary to a healthy ecosystem were supportive. Text mining analysis revealed that those who disagreed with the reintroduction were thinking about “people” while those who agreed emphasized the need to control an increasing deer population and to prevent related damage. In contrast to previous research, our survey revealed that it is not people’s propensity for wolves (i.e., whether they like or hate wolves), but their understanding of the ecological impact of reintroduced wolves, that influences their support. In summary, our findings suggest that public attitudes toward the reintroduction of wolves may become more favorable if people were informed of the scientific findings that Japanese and continental wolves are the same species and that their presence will positively impact the ecosystem.

The cost of deer to trees: changes in resource allocation from growth-related traits and phenolic content to structural defence

Background and aims – Plants may use various defence mechanisms to protect their tissues against deer browsing and the allocation of resources to defence may trade-off with plants’ growth. In a context of increasing deer populations in European forests, understanding the resource allocation strategies of trees is critical to better assess their ability to face an increasing browsing pressure. The aim of this study was to determine how deer removal affects the resource allocation to both defensive and growth-related traits in field conditions for three tree species (Abies alba, Picea abies and Fagus sylvatica).Methods – We compared eight pairs of fenced-unfenced plots to contrast plots with and without browsing pressure. The pairs were set up in 2005 and 2014 to compare different fencing duration. We measured leaf and shoot traits related to the defence against herbivores (phenolic content, structural resistance, C:N ratio) and to the investment in plants’ growth and productivity (specific leaf area and nutrient content). Key results – For the three species, the structural resistance of leaves and shoots was negatively correlated with SLA, nutrient content and phenolic content. For Abies alba, exclusion of deer decreased shoot structural resistance in favour of higher nutrient content, SLA and phenolic content. The fencing duration had no effect on the different measured traits. Conclusions – Our results support the assumption of a trade-off between structural defence and growth-related traits at the intraspecific scale for the three studied species. We also confirmed the hypothesis that exposure to deer browsing is involved in the resource allocation of woody species. For Abies alba, fencing led to a change in resource allocation from structural defence to growth-related traits and chemical defence.

The blame game: Using eDNA to identify species-specific tree browsing by red deer (Cervus elaphus) and roe deer (Capreolus capreolus) in a temperate forest

Increasing deer populations in many temperate regions can affect tree regeneration, resulting in severe long-term impacts on forest structure, composition and diversity. Of the most common deer species in Europe — red deer (Cervus elaphus) and roe deer (Capreolus capreolus) — roe deer are generally thought to have the highest impact on palatable tree species owing to their feeding niche. Although browsing and its potential consequences are well researched, less is known about the influence of specific deer species within multi-species ungulate communities on specific tree species. Environmental DNA (eDNA) allows the determination of species-specific browsing habits without the need for direct observations, facilitating effective targeting of management interventions. In this study eDNA was used to elucidate the browsing patterns of these two deer species in the temperate forest of the Bavarian Forest National Park, Germany and analysed the influence of tree species, management type and height of browsing, on the success rate of the method. Samples were collected from twigs used in feeding trials from enclosures containing red deer or roe deer and from naturally browsed twigs in three different management types within the national park. eDNA was successfully amplified from 98% of the feeding trial samples, and the correct deer species was identified for all samples. eDNA was successfully amplified from approximately 50% of the naturally browsed samples. Neither management type, tree species, nor height of browsing had any significant influence on the success of the method. For silver fir and rowan, no significant difference was found in the proportion of browsing events attributable to roe or red deer, when the two deer species occur at similar densities. These results indicate that roe deer might not always be disproportionately responsible for the browsing of palatable tree species as expected from its food niche. Roe deer were significantly more responsible for browsing at lower heights than red deer. Although not statistically significant, roe deer were more responsible for browsing in intact forest compared to bark-beetle-impact forest, with the opposite relationship for red deer.

Climate change effects on deer and moose in the Midwest

ABSTRACTClimate change is an increasing concern for wildlife managers across the United States and Canada. Because climate change may alter populations and harvest dynamics of key species in the region, midwestern states have identified the effects of climate change on ungulates as a priority research area. We conducted a literature review of projected climate change in the Midwest and the potential effects on white‐tailed deer (Odocoileus virginianus) and moose (Alces alces). Warmer temperatures and decreasing snowpack in the region favor survival of white‐tailed deer. In contrast, moose may become physiologically stressed in response to warming, and increasing deer populations spreading disease will exacerbate the problem. Although there is some uncertainty about exactly how the climate will change, and to what degree, robust projections suggest that deer populations will increase in response to climate change and moose populations will decrease. Managers can begin preparing for these changes by proactively creating management plans that take this into account. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society

What factors affect national-scale deer population dynamics in the Republic of Ireland?

ABSTRACTResearch into deer population dynamics has mostly focused on community or landscape scales in the Republic of Ireland. However, in order to propose national deer management strategies to confront the increasing deer populations in recent years, a larger scale analysis of deer populations is necessary. In this inter-county, national study, generalised linear mixed models were utilised to examine the relationship between the harvest rate (defined as the numbers harvested per 100 ha in this study) data and factors identified in past research as contributing to deer population dynamics on a county basis, where annual county-level deer harvest records were used to reflect deer populations by species. The procedures were repeated for each species and significant factors and their impacts were identified for each county. The results suggested that multiple factors affect deer population dynamics; for instance, increases in forest cover tended to result in increases in deer populations of all species, and the presence of red and sika deer populations in a county had a positive influence on hybrid deer populations. National migration maps for each deer species were produced, as well as predictions of future population trends. The outcome of this study can be used to guide the development of a national deer management strategy and the prioritisation, on a regional basis, of deer control measures.

Development of Northern White-Cedar (Thuja occidentalis L.) Plantations within and outside Deer Yards

Regional surveys done over the last decades show a clear decline in abundance of Northern white-cedar (Thuja occidentalis L.) throughout its range. A lack of seed trees, difficulties in the establishment of natural regeneration and high browsing pressure caused by increasing deer populations have been identified as plausible causes. Current silvicultural strategies for cedar restoration recommend partial cutting to promote and release natural regeneration, but there is also a need to restore the species in areas where it became absent. Yet, little attention has been given to cedar plantations. This study provides a first characterisation of the effects of competition, silvicultural treatments and deer, moose and hare browsing on planted cedar growth, survival, and stem form. Pure and mixed cedar plantations aged 5–27 years located in Eastern Québec were sampled. Both inside and outside deer yards, planted cedars showed high survival rates and were generally subject to low browsing pressure, but 45% were forked. Cedars showed high growth rates and strong reaction to stand opening. Results suggest that at reduced competition levels, a 9-year browser exclusion could be sufficient to establish safe-from-browsing cedar stands of >3 m in height.

Swedish Forestry, Forest Pasture Grazing by Livestock, and Game Browsing Pressure Since 1900

Abstract Growing numbers of wild ungulates are increasingly seen by concerned authorities in Europe as posing serious management problems, which include increasing browsing pressure by moose ( Alces alces ) and roe deer ( Capreolus capreolus ) in Swedish forests. Recent investigations by the Swedish Forest Agency identify high browsing pressure as the main reason for a recent decline in regeneration of Scots pine ( Pinus sylvestris ), one of the two main commercial species in Swedish forestry. The high browsing pressure is also having a negative impact on biodiversity. Thus, voices within the forest community claim that browsing pressure has never been so high. This paper examines that claim from a historical perspective by comparing livestock grazing in forest pastures a century ago with contemporary game browsing, and identifying the main factors driving both the livestock exodus from Swedish forests during the first half of the twentieth century and the rapid increase in deer populations during the second half. Finally, testing the claim that browsing impact has never been so high, past grazing and present browsing are theoretically sized up and compared. Estimates of live weights and numbers of large herbivores in 1902 and 2012 are used. The result indicates that the claim might possibly be lacking in historical context.

Effects of an increase in population of sika deer on beetle communities in deciduous forests.

The overabundance of large herbivores is now recognized as a serious ecological problem. However, the resulting ecological consequences remain poorly understood. The ecological effects of an increase in sika deer, Cervus nippon Temminck (Cervidae), on three insect groups of beetles was investigated: ground beetles (Carabidae), carrion beetles (Silphidae), and dung beetles (Scarabaeidae and Geotrupidae) on Nakanoshima Island, Hokkaido, northern Japan. We collected beetles on Nakanoshima Island (experimental site) and lakeshore areas (control site) and compared the species richness, abundance, diversity index, and community composition of beetles between the sites. Results showed that although both species diversity and abundance of carabid beetles were significantly higher at the lakeshore site, those of dung and carrion beetles were higher at the island site. It was additionally observed that abundance of larger carabid beetles was higher at the lakeshore site, whereas that of small-sized carabid beetles did not differ between the lakeshore and island sites. For dung beetles, abundance of smaller species was higher at the island site, whereas that of large species did not differ between the lakeshore and island sites. Abundance of two body sizes (small and large) of carrion beetles were both higher at the island site. Overall, the findings of this study demonstrated that an increase in deer population altered the insect assemblages at an island scale, suggesting further changes in ecosystem functions and services in this region.

Living on the boundary of a post-disturbance forest area: The negative influence of security cover on red deer home range size

In the face of climate change and the probable rise in the frequency of severe natural disturbances, successful management of forest ecosystems requires profound knowledge, including the one connected with the temporal and spatial relations between populations of wild herbivores and their habitats. Animal location data collected with VHF collars and spatial GIS data were used to investigate home range size of red deer living along the boundary of two contrasting forest environments which were created after a large-scale (10,000ha) stand-replacing fire in south-western Poland. We found male home ranges to be nearly twice as large as female ones. Surprisingly, the percentage of the burned area (less penetrated by humans, although of lower food availability) was negatively correlated with deer home range sizes in all seasons. The conditions in the post-disturbance forest were relatively stable during the year, which could explain the lack of differences between seasonal home ranges. Our findings suggest that the relationship between home range size and open habitats may be determined by the distribution of the latter: patches offering the best forage seem to be worth the effort of travelling, even at the cost of home range expansion. Heterogeneity features (patch and edge density) of forest interior habitats in this study did not emerge as an important determinant of the total size of home ranges. When burned and unburned areas were analysed separately, the results revealed that their size could be at least seasonally adjusted to habitat heterogeneity: in the burned area, deer seemed to travel longer distances between preferred patches (an increase in patch density was positively correlated with home range size), whereas the opposite was observed in the undisturbed forest in winter and spring. Our findings suggest that in populations under strong hunting pressure, security cover is a key resource, determining deer space use, especially in post-disturbance forests. We concluded that large areas of cover-offering habitats may lead to local increase in deer population and higher browsing pressure also in surrounding forests. Proper planning and introduction of feeding places (open areas) might help to control the population size by hunters and thus mitigate this effect.

Positive plant and bird diversity response to experimental deer population reduction after decades of uncontrolled browsing

AbstractAimDuring the 20th century, deer (family Cervidae), both native and introduced populations, dramatically increased in abundance in many parts of the world and became seen as major threats to biodiversity in forest ecosystems. Here, we evaluated the consequences that restoring top‐down herbivore population control has on plants and birds.LocationForest ecosystems of Haida Gwaii (British Columbia, Canada) where introduced black‐tailed deer (Odocoileus hemionus) have dramatically limited tree regeneration and simplified understorey plant, insect and bird assemblages.MethodsWe experimentally assessed ecosystem‐wide responses of plant and bird communities to a ~80% reduction of deer abundance on two medium‐sized islands (146 and 249 ha). We monitored changes in plant and bird communities for the 13 years following the start of culling and used two islands without culling and a set of exclosures as controls.ResultsNative plant communities increased in cover and richness after culling, while introduced plants decreased. Birds that depend on understorey vegetation for feeding and/or breeding increased significantly after deer were reduced in abundance but species not dependent on understorey vegetation did not. Finally, on control islands, plant and bird communities were stable or declined throughout the study period.Main conclusionsBiodiversity losses caused by current continental‐scale trends of increasing deer populations are potentially reversible. We demonstrate that controlling large herbivore populations (native or introduced) offers significant conservation benefits to forest understorey plant communities, even to those most negatively affected by uncontrolled browsing. We also report, for the first time, strong evidence that higher trophic levels (birds) can respond rapidly and positively to herbivore density control.

Does sika deer overabundance exert cascading effects on the raccoon dog population?

Habitat structure in Oku-Nikko, Japan, has been substantially modified by the overabundance of sika deer (Cervus nippon). A deer-proof fence (15.0 km and 900 ha) was constructed in 2001 to conserve vegetation. Although the understory inside the fence is dominated by Sasa nipponica (hereafter, Sasa), an important forage plant for deer, that outside the fence is dominated by Aster ageratoides leiophyllus (hereafter, Aster), an unpalatable plant to deer, and, partly, by bare floor. In this study, we examined the effects of deer on ground-dwelling insects and earthworms, the primary food resources of raccoon dogs (Nyctereutes procyonoides), and, thus, the bottom-up cascading effects of the herbivore on the omnivorous carnivore. Between July and September 2008, we examined the abundance of insects and earthworms by pitfall trapping and hand-sorting methods, respectively, both inside and outside the fence. The abundance of earthworms and insects (Scarabaeidae and Rhaphidophoridae) was higher on forest floors with Aster and/or bare floors outside the fence than on those with Sasa inside the fence. These results indicate that the increasing deer population in this area probably increased the number of these invertebrates outside the fence by modifying understory vegetation and/or depositing dung. Furthermore, the sighting rates of raccoon dogs obtained by spotlight counts were greater outside than inside the fence, suggesting that deer probably exert bottom-up cascading effects on raccoon dogs, at least during May to November, when the invertebrates are predominantly fed on by the omnivorous carnivore.

Declining woodland birds in North America: should we blame Bambi?

AbstractAimWe evaluate the possible link between increasing deer populations and declines in woodland birds.LocationNorth American continent.MethodsWe used a group of 73 forest bird species that had been tested for their sensitivity to the impact of overabundant deer on forest understory. We used Breeding Bird Survey data to assess population trends for these 73 songbird species between 1966 and 2009, a period of marked continent‐wide increases in white‐tailed (Odocoileus virginianus) and mule or black‐tailed (Odocoileus hemionus) deer.ResultsWe show a continent‐wide link between increase in deer populations and declines in forest–songbird species‐dependent on understory for nesting and/or foraging.Main conclusionsIncreasing deer populations may actually play an important and underestimated role in the decline of North American songbirds.