High Deer Densities Research Articles

There is only one winner: The negative impact of red deer density on roe deer numbers and distribution in the Słowiński National Park and its vicinity.

Red and roe deer are the most numerous cervids in Europe, and they occur in sympatry in most regions. Roe deer were considered to be an inferior competitor in studies in which they co‐occurred with fallow deer or muntjac. Despite the remarkable overlap of their ranges, there are few studies on the competition between the red and roe deer. Since interspecific interactions among ungulates are often related to their mutual densities, the current study focused on the effects of high red deer density on the roe deer numbers and spatial distribution in the unhunted Słowiński National Park (SNP) in northern Poland and forest districts open to hunting bordering the park. Using fecal pellet group counts, it was found that in the forest districts (where red deer densities were 2–3 times lower than in the SNP), roe deer densities were significantly higher than in the park. The red‐to‐roe deer density ratio was 10.8 and 2.7, in the SNP and the surrounding forest districts, respectively. Moreover, in the SNP, the roe deer distribution was negatively affected by the red deer habitat use, while in the hunting areas, such an effect was not recorded. The negative influence of the red deer on the roe deer population in the park was most probably due to the red deer impact on food availability. The biomass of the plant groups forming the staple food of the roe deer (Rubus spp., forbs, dwarf shrubs) was significantly higher in the fenced plots than in the unfenced ones. Lack of hunting in the protected areas may benefit only some species in ungulate assemblages which, in turn, may contradict one of their objectives—to maintain viable and ecologically functional populations.

Differential and interacting impacts of invasive plants and white-tailed deer in eastern U.S. forests

Forests in eastern North America are experiencing high densities of white-tailed deer (Odocoileus virginianus) and encroachment by invasive plants, both of which threaten native biodiversity. We review the literature on deer and invasive plant impacts focusing on studies that simultaneously evaluate the consequences of both. Deer have more frequent and more consistently negative effects than invasive plants. Widespread deer impacts now threaten many native plant species through much of their range. In contrast, invasive plant effects currently remain more localized and/or of smaller extent within forests. Deer impacts are also cumulative, hitting preferred plant species especially hard as they decline in density. This generates difficult-to-reverse legacy effects. Invasive plant effects, in contrast, tend to be more diffuse and may be more readily reversed. High deer populations also shift physical and chemical conditions in soils promoting “invasion cascades” involving non-native earthworms and certain introduced plants. Removing invasive plants without reducing deer populations can increase deer impacts on native species. Management should be integrated to address both deer and invasive plants. To safeguard and restore native biota when resources are limited, however, it may be most effective for managers to first reduce deer populations before investing in efforts to reduce invasive populations (except when invasions are at an early stage). We should rethink and reform traditional approaches to managing deer so that we can better integrate land vegetation with wildlife management to achieve broad public objectives. Interacting effects of high ungulate populations and invasive plants deserve further study to determine whether similar recommendations apply to other regions.

Bovine Tuberculosis: The Emergence of a New Wildlife Maintenance Host in Ireland.

Despite advances in herd management, tuberculosis (TB) continues to affect ~0. 5% of Ireland's national cattle herd annually. It is clear that any “final” eradication of TB in cattle will need to address all TB maintenance hosts in the same environment. In Ireland and the UK, European Badgers (Meles meles) are a known TB maintenance host, while deer are recognised as spillover hosts. However, deer have been identified as maintenance hosts in other countries and Sika deer, specifically, have been identified with TB in Ireland. We examined the power of cattle, badger and Sika deer densities (at the county level) to predict cattle TB-breakdowns in Ireland, at both the herd and the individual level, using data collected between 2000 and 2018. Our hypothesis was that any positive correlations between deer density and cattle TB-breakdowns would implicate deer as TB maintenance hosts. Using linear multiple regressions, we found positive correlations between deer density and cattle TB-breakdowns at both the herd and individual levels. Since Sika deer in County Wicklow are known to have TB, we ran further regressions against subsets of data which excluded individual Irish counties. Analyses excluding Wicklow data showed much weaker correlations between Sika deer density and cattle TB-breakdowns at both the herd and individual levels, suggesting that these correlations are strongest in County Wicklow. A similar effect for badger density was seen in County Leitrim. While locally high densities of Sika deer persist in Irish counties, we believe they should be considered an integral part of any TB-control programme for those areas.

Can coppicing planted saplings improve the growing position of mid-tolerant northern hardwood tree species in harvest gaps?

Group harvesting is often used to regenerate mid-tolerant tree species. However, in managed northern hardwood forests of the Great Lakes region, regeneration failures are common among mid-tolerant species regardless of gap size. Coppicing advance regeneration has the potential to alter recruitment patterns within harvest gaps, as some mid-tolerant species have large dormant season carbohydrate reserves in the root system. However, the comparative sprouting abilities of northern hardwood saplings are not well quantified. Furthermore, variation in light availability and chronic browsing from white-tailed deer may modify comparative sprouting abilities. In this study, we tracked the effects of dormant season coppicing and deer exclusion on the initial sprouting response and five-year survival, height growth, and final height of seven-year-old volunteer white ash saplings and planted yellow birch, paper birch, northern red oak, sugar maple, red maple, and American beech saplings across a gradient of harvest gap sizes (10–35 m diameter, <0.5–1.25 tree height) in a mature even-aged northern hardwood stand in northern Lower Michigan, USA. In addition, saplings were given a growing position ranking, which integrated sapling final height and survival status relative to competitors to evaluate the effects of coppicing and deer exclusion on sapling development. Overall, coppicing produced a strong initial sprouting response with nearly all red maple and northern red oak stems initially sprouting. In the absence of deer, appreciable differences in sprout survival and height growth occurred among mid-tolerant and intolerant species and contributed to changes in growing position. Northern red oak sprouts significantly gained growing position over all species through a combination of high survival and modest height growth across all gap sizes. In contrast, coppiced yellow birch and paper birch sprout survival was significantly lower than uncoppiced stems, which contributed to declines in growing position for both species across all gap sizes. Coppicing in the absence of deer had less effect on the growing position of mid-tolerant red maple and white ash and shade tolerant sugar maple and American beech. Without deer exclusion, browsing limited the effectiveness of coppicing by reducing height growth and final height of all mid-tolerant species. Collectively, our results indicate that coppicing does not benefit mid-tolerant species equally and is unlikely to benefit browsing-preferred species in areas with high deer density. Nevertheless, in areas of lower deer density or in situations where sprouts can be protected, coppicing may improve the competitiveness of northern red oak saplings within harvest gaps.

Modeling how to achieve localized areas of reduced white-tailed deer density

Localized management of white-tailed deer (Odocoileus virginianus) involves the removal of matriarchal family units with the intent to create areas of reduced deer density. However, application of this approach has not always been successful, possibly because of female dispersal and high deer densities. We developed a spatially explicit, agent-based model to investigate the intensity of deer removal required to locally reduce deer density depending on the surrounding deer density, dispersal behavior, and size and shape of the area of localized reduction. Application of this model is illustrated using the example of abundant deer populations in Pennsylvania, USA. Most scenarios required at least 5 years before substantial deer density reductions occurred. Our model indicated that a localized reduction was successful for scenarios in which the surrounding deer density was lowest (30 deer/mi²), localized antlerless harvest rates were ≥ 30%, and the removal area was ≥ 5 mi² . When the size of the removal area was < 5 mi2, end population density was highly variable and, in some scenarios, exceeded the initial density. The shape of the area of localized reduction had less influence on the ability to reduce deer density than the size. There were no differences in mean deer density in the same size circle or square removal areas. Similarly, increasing the ratio of sides (length: width) in rectangular removal areas had little influence on the ability to locally reduce deer densities. Situations in which deer density was higher (40 or 50 deer/mi2) required antlerless removal rates to exceed 30% and took more than 5 years to considerably reduce density in the localized area regardless of its size. These results indicate that the size of the removal area, surrounding deer density, and antlerless harvest rate are the most influential factors in locally reducing deer density. Therefore, localized management likely can be an effective strategy for lower density herds, especially in larger removal areas. For high density herds, the success of this strategy would depend most on the ability of resource managers to achieve consistently high antlerless harvest rates.

Az amerikai májmétely (Fascioloides magna) expanziója Délnyugat-Magyarországon – Előzetes közlemény

Európában a Fascioloides magna több endémiás területen fordul elő. A féreg a különböző élőhelyek között a végleges gazdák mozgásával, a köztigazdák széthurcolásával, illetve állatszállítások útján terjed. A tanulmányban a szerzők öt, Belső-Somogyban elejtett gímszarvas esetfeldolgozásával mutatják be a F. magna fertőzöttség terjedését. A parazitológiai vizsgálatok során négy állatban, eltérő intenzitással fordult elő a faj, egy esetben csak a férgek májban történő vándorlásának jellegzetes nyomait figyelték meg. A nagy amerikai májmétely 2018-ban megismert legészakibb belső-somogyi előfordulása és a jelenlegi előfordulások között a távolságok 21,0-37,8 km közé estek. Az eredmények a F. magna további dél-dunántúli terjedését támasztják alá.

Small shrubs with large importance? Smaller deer may increase the moose-forestry conflict through feeding competition over Vaccinium shrubs in the field layer

The moose (Alces alces) is a dominant large mammalian herbivore in the world’s boreal zones. Moose exert significant browsing impacts on forest vegetation and are therefore often at the centre of wildlife-forestry conflicts. Consequently, understanding the drivers of their foraging behaviour is crucial for mitigating such conflicts. Management of moose in large parts of its range currently largely ignores the fact that moose foraging is influenced by increasing populations of sympatric deer species. In such multispecies systems, resource partitioning may be driven by foraging height and bite size. Feeding competition with smaller species might replace larger species from the field layer and drive them towards higher foraging strata offering larger bites. This bite size hypothesis has been well documented for African ungulate communities. Based on a large diet DNA metabarcoding dataset we suggest that feeding competition from three smaller deer species (red deer Cervus elaphus, fallow deer Dama dama, and roe deer Capreolus capreolus) over Vaccinium shrubs in the forest field layer might drive moose towards increasing consumption of Scots pine (Pinus sylvestris) in Sweden. We found that in areas of high deer density, moose diets consistently contained less Vaccinium and higher proportions of pine over three spring periods. Utilization of these food items by the smaller deer species was either unaffected by deer density or, for Vaccinium showed the opposite pattern to moose, i.e., increases of proportions in the diet of roe and red deer with increasing deer density. Availability of pine and Vaccinium, measured as proportion of available bites, did not explain the observed patterns. Our results suggest that managing key food items like Vaccinium and the populations of smaller deer may play an important role in controlling browsing impacts of moose on pine.

Clonal Spread of Quinolone-Resistant Escherichia coli among Sika Deer (Cervus nippon) Inhabiting an Urban City Park in Japan.

The emergence and dissemination of resistance to clinically important antimicrobials in wild animals is of great concern. The aim of our study was to reveal the prevalence and intraspecies dissemination of quinolone-resistant Escherichia coli (QREC) in sika deer (Cervus nippon) in Nara Park, a famous tourist spot in Japan. Fecal samples were collected from 59 wild deer in Nara Park between July and October 2018. We isolated QREC using deoxycholate-hydrogen sulfide-lactose agar containing nalidixic acid and subjected it to antimicrobial susceptibility testing. The mutations in the quinolone resistance-determining region (QRDR) of the gyrA and parC genes of the isolates were analyzed and fragment patterns of genomic DNA were compared by pulsed-field gel electrophoresis (PFGE). A total of 105 QREC isolates were obtained from 41 deer (70%). All isolates had mutations within the QRDR. Other than quinolone resistance, QREC isolates also showed resistance to various other antimicrobial agents. The QREC isolates were classified into 15 PFGE clusters, of which seven were observed in multiple deer. Our results suggest clonal transmission of QREC in a high-density deer population. Spread of QREC in deer inhabiting a tourist location could have potential impact on public health.

Regaining the History of Deer Populations and Densities in the Southeastern United States

ABSTRACTDespite widespread interest in white‐tailed deer (Odocoileus virginianus) in the southeastern United States, historical deer populations and densities have not been compiled into one accessible source. We digitized maps from 1950, 1970, 1982, and 2003 and reviewed literature to quantify population sizes and densities in the Southeast, although previous estimates may not be accurate. Deer population sizes declined to a minimum of &lt;215,000 during the early 1900s. Population sizes and mean deer densities were 304,000 and 0.22 deer/km2 by 1940, 476,000 and 0.35 deer/km2 by 1950, 2.9 million to 4.1 million and 2.2 to 3.1 deer/km2 by approximately 1970, 6.2 million and 4.6 deer/km2 by 1982, and 10.8 million to 12 million and 8 to 9 deer/km2 by about 2003. Although our estimates are likely not completely accurate in space and time, due to difficulty of counting animals, they provide the best available information and a range and trend in values, with general corroboration among sources. The current population size may be greater than during pre‐Euro‐American settlement, when based on minimum historical deer densities, or, conversely, the current population may be within the bounds of mid to high historical deer densities. Large deer densities trigger a research need to evaluate deer effects on vegetation, but threshold densities when deer are damaging to herbaceous plants may need to be reconsidered. Instead, we conjecture that deer may be considered a natural disturbance helpful in controlling increased tree densities during the past century, albeit placing a secondary stress upon declining herbaceous plants, which are losing ground to trees. © 2020 The Wildlife Society.

Seasonal Variation in and Nutritional Implications of the Diet Composition of a Sika Deer (Cervus nippon) Population in a Heavily Browsed Habitat: Contribution of Canopy Subsidies

Canopy subsidies have been attracting attention as food resources sustaining high-density deer populations in heavily browsed habitats; however, evaluation of the contribution of canopy subsidies to deer diets is still limited. We investigated the seasonal variation in and the nutritional value of the diet composition of a sika deer population in the Tanzawa Mountains using 126 rumen content samples collected from May 2015 to June 2016. The deer population depended more on evergreen tree leaves in the winter than it did in the other seasons. In the summer and autumn, the occupancy ratio of woody tissues (e.g., twigs) was relatively high compared with other seasons. Even in the spring, woody tissues and deciduous tree leaves accounted for a certain proportion of the sika deer diet. The crude protein (CP) content of the rumen content samples collected in spring (9.56–22.69%) satisfied the minimum dietary CP requirement estimates for maximum growth. The CP content of the rumen content samples collected in the other three seasons satisfied the minimum dietary CP requirement for maintenance. We suggested that canopy subsidies make high quantitative and qualitative contributions to the sustainment of high-density deer populations in heavily browsed habitats.

Mycobacterium bovis genomics reveals transmission of infection between cattle and deer in Ireland.

Control of bovine tuberculosis (bTB), caused by Mycobacterium bovis , in the Republic of Ireland costs €84 million each year. Badgers are recognized as being a wildlife source for M. bovis infection of cattle. Deer are thought to act as spillover hosts for infection; however, population density is recognized as an important driver in shifting their epidemiological role, and deer populations across the country have been increasing in density and range. County Wicklow represents one specific area in the Republic of Ireland with a high density of deer that has had consistently high bTB prevalence for over a decade, despite control operations in both cattle and badgers. Our research used whole-genome sequencing of M. bovis sourced from infected cattle, deer and badgers in County Wicklow to evaluate whether the epidemiological role of deer could have shifted from spillover host to source. Our analyses reveal that cattle and deer share highly similar M. bovis strains, suggesting that transmission between these species is occurring in the area. In addition, the high level of diversity observed in the sampled deer population suggests deer may be acting as a source of infection for local cattle populations. These findings have important implications for the control and ultimate eradication of bTB in Ireland.

Manipulating forage and risk avoidance to increase white-tailed deer vulnerability to hunters

A tradeoff between forage acquisition and predation avoidance contributes to shape space use by herbivores. The manipulation of structural components of the habitat, such as forage and forest cover may alter this tradeoff. The idea of influencing space use of herbivores is appealing for wildlife managers that aim to locally modify herbivore densities and increase their vulnerability to hunting. We attempted to manipulate the tradeoff between forage acquisition and risk avoidance of white-tailed deer Odocoileus virginianus on Anticosti Island (Quebec, Canada) using experimental hunting fields varying in forage production (fertilized or unfertilized fields) and residual forest cover (30 or 60-m-wide forested strips between fields). In this system with high deer density, no natural predator and limited forage, fecal group surveys and camera traps demonstrated greater use of fertilized fields. Residual forest cover did not impact habitat use, suggesting that use of the experimental fields was mainly driven by the benefits of foraging compared to the costs of avoiding hunters. Deer vulnerability to hunting, however, differed with residual forest cover: hunters saw more deer per hour in fields separated by 30-m-wide forested strips compared to fields separated by 60-m-wide forested strips. That hunters did not detect the difference in deer use between fertilized and unfertilized fields suggests that deer vulnerability to hunting and deer use could be modified by different structural components of the habitat. Our results provide useful insights for wildlife managers that have to deal with conflicting goals such as maintaining hunter satisfaction with high observation rates of deer while reducing the negative impacts of high deer densities on their body condition and, on the composition and structure of forests.

Reviewing Fire, Climate, Deer, and Foundation Species as Drivers of Historically Open Oak and Pine Forests and Transition to Closed Forests

Historically open oak and pine savannas and woodlands have transitioned to closed forests comprised of increased numbers of tree species throughout the eastern United States. We reviewed evidence for and against a suite of previously postulated drivers of forest transition focused on 1) change in fire regimes, 2) increased precipitation, 3) increased white-tailed deer densities, and 4) loss of American chestnut. We found that fire and fire exclusion provide a parsimonious mechanism for historical dominance by open forests of fire-tolerant oak and/or pine species and subsequent transition to closed forests with fire-sensitive tree species that fill the vertical profile. Based on statistical tests, increased precipitation during the past century was within historical ranges and thus fails to provide an explanation for forest change; additionally, precipitation variability is incongruent with tree traits (i.e. both drought-tolerant and drought-intolerant species have increased and decreased) and patterns of tree establishment. Similarly, current deer densities fail to provide a statistical relationship to explain tree densities at regional scales, species trends are unrelated to deer browse preferences, and both historically open forests and contemporary closed forests contained high deer densities. Functional extinction of the American chestnut had localized impacts but was not abundant compared to oak or widespread enough in distribution to match forest transitions throughout the eastern United States. Although Euro-American settlement affected many processes, not all changes were consistent enough to cause transitions in forest composition and structure that generally trailed westward expansion by Euro-American settlers. Evidence about these drivers continues to mount and we recognize the need for further research and continual re-evaluation of drivers of historical forests and forest change due to importance for understanding and management of these ecosystems.

Effects of culling white-tailed deer on tree regeneration and Microstegium vimineum, an invasive grass

Reduction of forest regeneration due to overbrowsing by white-tailed deer is a growing concern for land managers. Abundant deer can impede forest regeneration through direct predation on tree seedlings. Additionally high deer density can facilitate the establishment of a dense understory of browse tolerant plant species that shades seedlings and persists even in the absence of deer. In response to these challenges, land managers have sought to reduce deer herds to restore tree regeneration, but few studies have evaluated the effectiveness of this management. Our study took place in Catoctin Mountain Park, a US National Park Service unit with a history of high deer density. The park has been heavily invaded by Microstegium vimineum, an invasive grass that can completely cover the forest floor. Using permanent plots established prior to the start of deer management, we were able to assess the joint effects of deer culling and M. vimineum on tree seedling density. We found that tree seedling density increased in response to deer reductions. M. vimineum cover initially increased, but then decreased. Seedling densities were higher in plots with more M. vimineum cover, indicating that it did not form a recalcitrant understory that would suppress regeneration. However, eight years after deer management began, few tree seedlings were >30 cm tall, implying that it will be many years before they grow into the sapling stage. Our results indicate that deer culling can be an effective tool in restoring tree regeneration despite the presence of M. vimineum, but that success will require a long-term commitment.

Abundant artificial grasslands around forests increase the deer impact on forest vegetation

Recent research suggests that deer impact on forest vegetation differs according to the surrounding landscape composition. However, there is no consistent trend on how food-rich habitat affects deer browsing impact on forest vegetation. The study took place in Yatsugatake region (Japan) where forests dominate, there are many artificial grasslands with various size, and large crop fields exist around urban area. We examined whether (1) the surrounding abundant alternative food (in this study, artificial grasslands) in forests increases deer density and (2) the high deer density affects forest vegetation more seriously. We evaluated the coverage of understory vegetation and the occurrence of debarking on standing trees. This study demonstrated that the abundant surrounding artificial grasslands increased deer density in forests. High deer density impacted forest vegetation negatively. Pellet group number was significantly higher in forests with high percentage of artificial grassland area and low percentage of crop field area. It was also higher in evergreen forests compared with other forest types. The coverage of understory vegetation was significantly reduced on the plots where many pellet groups were found. The occurrence of debarking on standing trees was significantly higher on the plots where many pellet groups were found than on plots with less pellets. In conclusion, abundance food-rich habitat around forests increases deer density in forests, which leads to a stronger impact of deer on forest vegetation.

The summer spatial distribution of Japanese serows (Capricornis crispus) in an area without predation risk

Prey species generally trade better forage habitats for those with lower predation risk, but whether absence of predation risk can modulate the trade-off between forage and security remains unclear. In addition, direct interspecific competition may lead to inferior species avoiding dominant species. I examined the summer spatial distribution of the Japanese serow (Capricornis crispus) at Mount Fuji in the absence of predation risk in relation to forage abundance, security (steep slope or poor visibility), and abundance of a dominant competitor, the sika deer (Cervus nippon). Only main forage abundance, terrain, and visibility affected serow summer spatial distribution, and serows were more abundant in areas with lower forage abundance, steeper slopes, and poorer visibility environments. Serows seem to use habitats with lower forage abundance in exchange for high security. My findings suggest that serows favor security rather than better forage abundance, even without predation risk, and have less behavioral plasticity related to predation risk (consistent with the idea of “ghosts of the predators past”). This may relate to serow phylogeny or characteristics, such as small body size, and solitary and sedentary habits. My findings also suggest that serows did not avoid habitats with high densities of sika deer.

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.

Characteristics of soils and plants in Nakanoshima Island of Lake Toya, with a high density of sika deer

Characteristics of soils and plants in Nakanoshima Island of Lake Toya, with a high density of sika deer

Deer do not affect short-term rates of vegetation recovery in overwash fans on Fire Island after Hurricane Sandy.

Coastal resilience is threatened as storm‐induced disturbances become more frequent and intense with anticipated changes in regional climate. After severe storms, rapid recovery of vegetation, especially that of dune‐stabilizing plants, is a fundamental property of coastal resilience. Herbivores may affect resilience by foraging and trampling in disturbed areas. Consequently, assessing the impacts of herbivores on recovering vegetation is important for coastal land management.We combined imagery classification, wildlife monitoring, and trend analysis to investigate effects of white‐tailed deer on recovery rates of vegetation four years poststorm in nine overwashed areas. We estimated local deer density with trail cameras, how it relates to an index of primary productivity, and assessed the relationship between deer density and rates of vegetation recovery in overwash fans.Prestorm vegetation cover consisted of shrubs and sporadic patches of beach grass. Poststorm cover was dominated by beach grass. At current rates, vegetation coverage will return to prestorm conditions within the decade, though community transition from grasses to shrubs will take much longer and will vary by site with dune formation.The effect of deer on rates of vegetation recovery was negative, but not statistically significant nor biologically compelling. Although effects of deer trampling on beach grass are evident in classified imagery, deer foraging on beach grass had little effect on its rate of spread throughout overwash fans.While the rate of spread of the primary dune‐building grass was not deleteriously affected by deer, locally high deer densities will likely affect the future establishment and development of herbs and shrubs, which are generally more palatable to deer than beach grass.

High density of keystone herbivore vs. conservation of natural resources: Factors affecting red deer distribution and impact on vegetation in Słowiński National Park, Poland

Rising deer densities are often in conflict with human activity. Among those conflicts there is conservation of natural resources whereas the protected areas, which are often unhunted, are known to form a hunting refuge resulting in higher deer densities than in the surrounding hunted areas. The issue is well known in many protected areas in the US, much less information on the matter is available in Europe, where protected areas are much smaller than in the other regions of the world. We studied red deer density, their distribution and pressure on vegetation in Słowiński National Park, northern Poland, whose land area is 11,000 ha and the forest area is just 6000 ha. Red deer density inside the forest area of the Park (ca. 26 ind./100 ha) was 2–3 times higher than in the surrounding hunted forest districts. Deer density in the Park had a limited influence (within a zone of 1 km) on the density of the species in the forest districts (only in one out of two districts). Despite its small size red deer densities within the Park were diversified and they were influenced by the forest site type and the distance to non-forest sites. Red deer density in the Park’s forests was inversely related to the distance to food abundant agricultural areas and positively related to the distance to the cover offering ones. Though the impact on forest vegetation (in terms of its biomass) was proportional to its availability, distance to non-forest sites strongly influenced the pressure. We conclude that that lack of hunting, together with favourable food and cover condition, can increase large herbivore densities even in relatively small protected areas. Since their high densities can have a negative direct and indirect influence on biodiversity and the primary goal of protected areas is biodiversity protection, we call for more research on the issue followed by a public debate in Europe concerning potential control of large herbivore populations in protected areas.