Impact Of Deer Research Articles

Effects of Sika Deer (Cervus nippon) and Dwarf Bamboo (Sasa senanensis) on TrilliumPopulations in Akan National Park, Eastern Hokkaido, Japan

The competition between Trillium spp. and other species could modify the utility of Trillium spp. as indicators of the impact of deer on forest vegetation. To evaluate whether Trillium spp. (T. camschatcense and T. tschonoskii) are appropriate indicators of the impact of sika deer (Cervus nippon) in the presence of dwarf bamboo (Sasa senanensis), which competes with Trillium populations, we examined the size class of large‐growth‐stage Trillium plants, the frequency of the presence of deer pellets and the coverage of S. senanensis in deer‐excluded sites (where deer have been eliminated since 1995) and unfenced control sites in Akan National Park, eastern Hokkaido, Japan. The result of a cumulative link mixed model (CLMM) suggests that size class at deer‐excluded sites is influenced by competitive understory species, even without deer grazing. The CLMM result for unfenced control sites suggests that C. nippon negatively influences the size class of Trillium populations; however, the negative effect weakened with increasing S. senanensis coverage. Thus, S. senanensis can function as an unpalatable neighbor that makes it difficult for C. nippon to detect Trillium plants. We conclude that the size class structure of Trillium spp. can be a useful index of C. nippon usage under sparse or medium S. senanensis understories; however, it is difficult to use these indices under dense S. senanensis understories because of the weakened negative effect of C. nippon grazing.

Opinion Bridging the disconnect between agencies and forest landowners to manage deer impact

<i>Opinion</i> Bridging the disconnect between agencies and forest landowners to manage deer impact

Impacts of white-tailed deer on regional patterns of forest tree recruitment

Local, short- to medium-term studies make clear that white-tailed deer can greatly suppress tree growth and survival in palatable tree species. To assess how deer have broadly affected patterns of tree recruitment across northern Wisconsin, we analyzed recruitment success in 11 common trees species that vary in palatability across 13,105 USFS - FIA plots sampled between 1983 and 2013. We also examined how recruitment in these species covaried with estimated deer densities here. Saplings of five palatable species were scarce relative to less palatable species and showed highly skewed distributions. Scarcity and skew provide reliable signals of deer impacts even when deer have severely reduced recruitment and/or no reliable deer density data are available. Deer densities ranged from 2.3 to 23 deer per km2 over a 30year period. Sapling numbers in two maples (Acer) and aspen (Populus) with intermediate palatability declined sharply in apparent response to higher deer density. Path analysis also reveals that deer act to cumulatively depress sapling recruitment in these species over successive decades. Together, these approaches show that deer have strongly depressed sapling recruitment in all taxa except Abies and Picea. As these impacts are now propagating into larger sized trees, deer are also altering canopy composition and dynamics. The tools developed here provide efficient and reliable indicators for monitoring deer impacts on forest tree recruitment using consistent data collected by public agencies.

The canary in the coal mine: Sprouts as a rapid indicator of browse impact in managed forests

Forest managers are frequently confronted with sustaining vegetation diversity and structure in landscapes experiencing high ungulate browsing pressure. Often, managers monitor browse damage and risk to plant communities using vegetation as indicators (i.e., phytoindicators). Although useful, the efficacy of traditional phytoindicators is sometimes hampered by limited distribution and abundance, variable browse susceptibility, and lagged responses. In contrast, sprouts possess traits which make them readily available and attractive to browsers, yet fairly resilient to tissue loss. Here, we experimentally evaluate whether hardwood tree stump sprouts are effective and sensitive phytoindicators of deer browse pressure. We measured sprout abundance and height in fenced and unfenced plots at 17 shelterwood harvested sites scattered across a 6500km2 region where deer densities varied by nearly an order of magnitude. We found browsing did not alter the proportion of stumps sprouting and sprout density; however, browse pressure varied among the four most abundant species. Acer rubrum and Acer saccharum were heavily browsed, although browse pressure on A. saccharum decreased in areas with greater canopy openness. Fagus grandifolia and Prunus serotina were less preferred. Differences in palatability altered size hierarchies. Averaged across all species, browsing reduced sprout height by 39%, relative to protected sprouts. Under ambient browsing, P. serotina was 60–100% taller than other species and significantly taller than A. saccharum and F. grandifolia. However, within fences A. saccharum and A. rubrum doubled in size, relative to browsed individuals, and were as tall as P. serotina. Deer impact on sprout height within unfenced forest stands was negatively correlated with estimated deer densities (R2=0.46). Thus, we suggest sprout surveys can provide a measure of impact across much larger areas. Our results demonstrate that sprouts, particularly those of Acer species, offer an abundant, easily measured, and reliable indicator of browse pressure. Moreover, browse impacts on sprouts emerged before impacts were detected on seedling abundance, height, or biomass. We argue sprouts can warn of imminent browse risk to seedlings (and perhaps non-woody vegetation) and thereby allow managers to take actions to mitigate or avert losses to the regenerating seedling cohort.

The impact of sika deer on butterflies in Japan

The impact of sika deer on butterflies in Japan

EFFECT OF RED DEER GRAZING ON ALPINE HAY MEADOWS: BIODIVERSITY AND MANAGEMENT IMPLICATIONS

Large mammalian herbivores are keystone species affecting the biodiversity and functioning of ecosystems, since herbivory directly influences plant species competitive ability. Thus, when managing habitats for conservation it is crucial to understand the selection patterns of large herbivores and their effect on plant diversity and assemblage. With this aim, we studied a pastoral system placed in central- eastern Alps, comparing late mowing with grazing by red deer. We found that, with high stocking rates, red deer significantly affects the species and functional composition of alpine productive pastures, mostly by competitive exclusion of subordinate species due to the spread of poorly palatable, competitive, stress-tolerant tall grasses with strong avoidance strategies. We argued that grazing by red deer with high stocking rates is harmful when acts on formerly managed meadows, while it has a positive impact on plant diversity of long-term abandoned grasslands. Our results indicated that grazing by red deer with high stoking rates hinders the spread of successional/ruderal species, but allows the establishment of competitive dominant tall grasses. Our findings also confirmed the hypothesis that the impact of red deer on grassland biodiversity follows the intermediate disturbance hypothesis.

Landscape-scale vegetation patterns influence small-scale grazing impacts

Understanding the distribution of herbivory is of great importance to planning the conservation management of plant communities. Control of wild and domestic large herbivore populations at large scales is commonly used to manipulate their impacts. However, the relationship between large scale population density and local impacts is often weak as the spatial layout of plant communities, and the herbivores' preferences for them, can drive the herbivores' habitat use. We tested the effects of proximity of a preferred plant community at scales up to 3km2 on the grazing impact of red deer (Cervus elaphus) on four plant communities of conservation importance. We also tested the relationship between grazing impacts and herbivore density at the scale of deer management units on the site. Grazing impact was measured using direct and indirect indicators of grazing. The area of the preferred species-rich grassland in proximity to the target site influenced grazing impacts on both preferred (grassland) and less-preferred (heath) communities. Grazing impacts on heaths were higher when there was more species-rich grassland present within 1000m. Grazing impacts on species-rich grasslands were lower when the area of species-rich grassland within 500m was small, especially when there was also more species-rich grasslands in the wider area (500–1000m away). Herbivore density was only weakly correlated to grazing impacts. Where plant communities with contrasting grazing sensitivity to or requirement for grazing to maintain them exist side by side, there is an inherent conflict in managing for the conservation of both. Our understanding of the role of spatial layout of adjacent communities as a determinant of herbivore impact may inform the management and prioritisation of the conservation of one plant community over others.

고라니(Hydropotes inermis)의 분변이 습지 토양의 CO&lt;sub&gt;2&lt;/sub&gt; flux에 미치는 영향

토양으로부터 방출되는 <TEX>$CO_2$</TEX>의 양은 전 지구적 지구 탄소 순환에서 가장 큰 방출 중 하나로 알려져 있다. 특히 토양 내 미생물의 유기물질 분해 과정에 의해 방출되는 이산화탄소의 양은 토양의 탄소 저장량을 장기적으로 결정하는 요인이 되므로 그 양을 정량화 하는 것이 필요하다. 본 연구는 토양에서 고라니의 분변이 <TEX>$CO_2$</TEX> 배출에 미치는 영향을 파악하기 위해 수행하였다. 그리고 고라니의 분변이 토양의 <TEX>$CO_2$</TEX> 배출에 주는 영향과 토지의 이용에 따라 변화하는 <TEX>$CO_2$</TEX> flux를 정량화 하였다. 그 결과 고라니 분변 내 많은 유기물질은 토양 미생물의 활성화에 영향을 주고 그로 인해 토양의 호흡 및 토양 내 물리 화학적인 변화가 발생되어 토양의 유기물 함량이 서로 다르게 나타남을 확인할 수 있었다. 특히 4개 지역의 토양(경작지, 휴경지, 버드나무 군락, 갈대습지)의 C/N ratio와 <TEX>$CO_2$</TEX> flux는 분변의 유무와 통계적으로 매우 유의미한 상관 관계를 나타냈으며(P<0.01), 분변의 영향을 받은 토양의 <TEX>$CO_2$</TEX> flux는 분변의 영향을 받지 않은 토양보다 2-20배 더 높은 것으로 나타났다. 이 연구는 고라니의 분변이 토양에 주는 영향과 야생동물 분변을 이용한 토양 물질 순환 연구를 통해 육상 생태계 및 토양권의 물질 순환과 그 영향의 정도를 정량화 하였다는 점에서 큰 의의가 있는 연구이다. The total global emission of <TEX>$CO_2$</TEX> from soils is recognized as one of the largest fluxes in the global carbon cycle. Especially it is necessary to quantify the amount of <TEX>$CO_2$</TEX> emitted by the organic material decomposition processes of microorganisms in the soil, because it becomes one of a factor for determining the carbon stocks in the soil. This study was conducted to estimate the impact of the Korean water deer(Hydropotes inermis)' feces to the soil organic matter. Also, effects of Korean water deer' feces on <TEX>$CO_2$</TEX> emissions of soil and land use pattern dependent <TEX>$CO_2$</TEX> flux quantification are studied. The organic materials in the Korean water deer' feces significantly changed organic matter content of soil and influenced the activity of soil microorganisms, both changing of respiration of the soil and physical chemical components in soil. In particular, C/N ratio and the <TEX>$CO_2$</TEX> flux of soil of four regions (Rice paddy, Fallow ground, Salix koreensis community, Phragmites australis community) showed a statistically highly significant correlation (P<0.01) with the presence or absence of feces. <TEX>$CO_2$</TEX> flux of soil affected by the feces was 2-20 times higher than the soil unaffected by the feces. This study has great significance to quantify the extent of the material circulation and its impact to the terrestrial ecosystem and soil zone throughout Korean water deer' feces. Feces of wildlife can affect soil and soil material circulation.

Significance of woody browse preferences in evaluating the impact of sika deer browsing on tree seedlings

The growing populations of sika deer (Cervus nippon yesoensis) in Hokkaido, Japan, are having increasingly negative impacts on forests. Although the percentage or frequency of browsed twigs and seedlings is a useful index of the impact of deer on forests, differences in the browse preferences of deer among tree species should also be considered. We evaluated the woody browse preferences of sika deer and examined a method for evaluating deer impacts based on the occurrence of browsing scars on seedlings, together with browse preferences. We also validated the percentages of browsed seedlings irrespective of browse preferences as an index of deer impact. We measured the heights of seedlings 30–200 cm tall in five 5 × 20 m plots located in Abies sachalinensis plantations in each of seven tracts and recorded browsing damage that occurred on leader shoots of seedlings. Browse species preference was evaluated using a generalized linear model (GLM) that included the seven tracts, species, and seedling height as explanatory variables. The results of the GLM suggest that differences in browse preferences among species are continuous and cannot be categorized discretely. The tract coefficients are considered to be an index of deer impact levels and can be estimated from the percentage of browsed seedlings for a species if the species coefficient is given. Simple percentages of browsed seedlings can also be used as an index of impact level, regardless of browse preferences, though these may be inaccurate, especially when the site is dominated by significantly preferred or avoided species.

The cross-ecosystem impact of deer on an endangered submerged macrophyte, Ranunculus nipponicus var. submersus

Macrophytes are a critical component of freshwater ecosystems and are often eaten by cervids. However, the impact of cervids on macrophytes is not well known. In this study, we investigated the effect of sika deer (Cervus nippon yesoensis) on the endangered macrophyte Ranunculus nipponicus var. submersus in a spring stream in southwestern Hokkaido, Japan. We monitored the frequency of stream habitat use by deer by using sensor cameras in photography mode for four seasons. We also monitored deer feeding behavior on R. nipponicus var. submersus using sensor cameras in movie mode. To quantitatively evaluate the impact of deer on R. nipponicus var. submersus, we conducted a field experiment in which deer were excluded from part of the stream. We selected 10 pairs of adjacent patches of R. nipponicus var. submersus and set up exclosures covering one patch in each pair. We assessed the frequency of deer feeding and trampling on the control patches using the sensor cameras in photography mode and measured the mean macrophyte stem length in the exclosure and control patches every month for four seasons. To compare abiotic conditions between the exclosure and control patches, we investigated canopy openness, water depth, water temperature, electrical conductivity, pH, current velocity, and water quality at each patch during the growing season. The frequency of deer in the stream habitat was higher from spring to summer than in other seasons. Direct evidence of deer feeding behavior on R. nipponicus var. submersus was recorded using the sensor cameras. Deer often fed on and trampled on the control patches, particularly from spring to summer. The R. nipponicus var. submersus stem length was longer in the exclosure patches than in control patches (P <0.001), and was 61% longer at maximum, despite no differences in abiotic conditions between the exclosure and control patches (all P >0.189). Stem growth of R. nipponicus var. submersus differed among seasons (P <0.001), and was low from winter to spring. In addition, exclosure and seasonality significantly affected stem length (P <0.001), and the difference between the exclosure and control patches was largest in the spring. These results indicated that deer feeding and trampling negatively affected R. nipponicus var. submersus, and this effect exhibited seasonality.

Monitoring populations of a guild of ungulates: implications for the conservation of a relict Mediterranean forest

We reviewed information on the population dynamics of ungulate populations in the Preserve of Castelporziano, Italy. Based upon hunting bags, long-term series of indices of abundance are available for fallow deer (Dama dama), wild boar (Sus scrofa majori), roe deer (Capreolus capreolus italicus), red deer (Cervus elaphus), and nilgai (Boselaphus tragocamelus) for the period from 1878 to 1986. In the absence of large predators, but in presence of hunting, population regulation is basically determined by density dependence. However, our data also show that roe deer are competitively affected by fallow deer, while the dynamics of wild boar is relatively disconnected from those of cervids. The impacts of climate and habitat variations on the growth rates of ungulates appeared to have limited relevance in this ecosystem. Standardised counts on green flush areas in spring, performed annually since 1988, show the presence of important interactions among the different species and the negative impact of fallow deer on roe deer. Further, spring counts suggest that wild boar populations exhibit stable fluctuations within a 3–5-year period. Nocturnal distance sampling estimates of fallow deer and wild boar populations, available since 2002, confirmed the broad picture obtained by spring counts, but also allowed us to estimate the actual population size and compute appropriate confidence intervals. The evaluation of the pros and cons of different monitoring methods is relevant to wildlife agencies to select the ones most suitable for offering a particular type of information and to underpin informed decisions on the best management practices to implement.

The impact of red deer on liverwort-rich oceanic heath vegetation

Background: There is concern about increasing numbers of large herbivores including red deer (Cervus elaphus), but little is known about their impact on bryophytes.Aims: This study set out to determine the effect of different localised densities of red deer on the internationally important Northern Atlantic hepatic mat, characteristic of oceanic heath vegetation, at four locations in the Scottish Highlands where sheep have been absent for decades.Methods: Thirty 7 m × 7 m plots were randomly located in each study area. The standing crop dung pellet group count method was used to estimate red deer density. Species richness, diversity and cover of hepatic mat liverworts were obtained from 1 m × 1 m quadrats placed at random within the sample plots. Calluna vulgaris cover, ericoid height, rock cover, gradient and altitude were also recorded.Results: Model simplification in analysis of covariance revealed a consistent pattern of decreasing cover of hepatic mat and Calluna with increasing red deer density at all four study areas. Northern Atlantic hepatic mat cover, diversity and species richness were positively correlated with Calluna cover.Conclusions: The data suggest that Calluna cover is reduced (through trampling and browsing) at high local densities of red deer which has had cascading effects on the Northern Atlantic hepatic mat. Alternative explanations are discussed.

Red deer impacts on the montane Racomitrium lanuginosum moss-heath community in north-west Scotland

Background: The effect of sheep grazing on the internationally important moss-heath community of the British uplands has been well studied but less is known about the impact of red deer (Cervus elaphus).Aim: To compare the impact of different densities of red deer on bryophytes and lichens associated with moss-heath vegetation at Beinn Eighe National Nature Reserve (low deer density) and a traditional sporting estate at Letterewe (with higher deer density), Scotland.Methods: Suitable pairs of summit study sites were selected at random, and species cover data were collected from thirty 1-m2 quadrats at each location. The dung pellet group count method was used to estimate red deer usage. Generalised linear models were fitted to the data.Results: Mean graminoid cover was significantly higher in two of the Letterewe study sites compared with their Beinn Eighe counterparts. Bryophyte cover and height in general matched the pattern for Racomitrium lanuginosum in that they were not significantly different between any of the study site pairings.Conclusions: Despite differences in mean deer density between the Beinn Eighe and Letterewe properties as a whole, red deer numbers actually using the exposed summit moss-heath vegetation were estimated to be very low. Therefore, bryophyte cover within the Letterewe summit study sites was not significantly different from that at Beinn Eighe.

L'impatto dei cervidi sulla rinnovazione artificiale di abete bianco. Primi risultati di una prova di impianto a piccolissimi gruppi

The aim of this study is to evaluate the impact of roe deer and fallow deer on Silver fir planted in small clusters after a clear cut in the Vallombrosa Forest (Florence, Italy). We measured height and deer impact on all firs planted in various sized clusters (from 6 to 59 fir per cluster, distance between firs in the cluster: 15-20 cm). Six years after planting, almost all the young fir were impacted by deer and often showed deviated stem growth as a result of past browsing. The majority of the silver fir saplings were less than one meter high, and were significantly smaller than firs planted inside a fenced control area. Plant position inside the cluster did not affect stem height and number of deer impacts. Height and impact incidenc ewas instead related to fir density within each cluster. We conclude that in a situation of maximum susceptibility to deer impact such as the one we have analyzed, planted firs are strongly affected by deer and cluster planting does not seem successful in reducing this impact.

The applicability of DNA barcoding for dietary analysis of sika deer

AbstractIn Japan, overgrazing by sika deer (Cervus nippon) has been suggested to cause a decline in forest understory vegetation. DNA barcoding has become an accepted method for analyzing the diets of animals and may be useful for evaluating the impact of sika deer on vegetation. However, the applicability of DNA barcoding in the dietary analysis of sika deer, particularly whether all of the food plants can be detected with sufficient taxonomic resolution and whether the results can be evaluated quantitatively, has not been investigated. We conducted a feeding trial by feeding five plant species to a captive sika deer and sequenced the chloroplast trnL P6 loop region from the sika deer’s fecal DNA using the Ion PGM sequencer. We detected the sequences of all of the food plants at the species level using the local (selfproduced) database and at the genus or family level with the global database. Although the sequences of some major food plants were detected with high frequency, the proportion of consumed food plants did not match the proportion of sequences obtained from fecal DNA. With further technical advances and the further completeness of the sequence database for vegetation, DNA barcoding will be a useful tool for the dietary study of sika deer.

L'impatto dei cervidi sulla produttività di cedui di cerro e castagno in Toscana. Indagini sperimentali e una proposta metodologica

The aim of this paper is to define a quick method for estimating the loss of wood production at rotation age caused by red deer and roe deer in chestnut coppices and in Turkey oak coppices. Three study areas were chosen for the study, with presence of different or overlapping red deer and roe deer populations. A total of 224 plots were selected in coppiced areas 2 and 5 years after felling. General yield tables were used for estimating coppice growth with and without browsing. Results showed a sensible difference between areas with red deer and areas with only roe deer. Chestnut coppices showed a better reaction to deer browsing compared to Turkey oak coppices. In Turkey oak coppices impacted by red deer browsing after felling, we estimated a sensible loss of production at traditional rotation age (18 years), and an average of 8 years was needed to attain the same level of production as in non-impacted coppices. With only roe deer, an average of 2 years were needed after rotation age to reach expected production. In chestnut coppices, at traditional rotation age (8 years) a loss of wood production was estimated in less than half of all the examined coppices. In these cases 2 more years were estimated to reach the expected production at rotation age. With red deer bark stripping was frequently recorded on both young and older shoots in chestnut coppices. We concluded that in areas with an overabundance of deer such as the one we examined here, there is the need for a change not only in deer management but also in forest management. A shared management strategy of both coppices and deer populations at the different space and time scales is necessary otherwise coppicing will continue to be a factor of strong attraction for deer impact, with serious risks for the conservation of coppice regeneration and productivity. The quick assessment method here presented can be a useful tool for supporting discussion and shared decisions among the different stakeholders involved in natural resource planning and management.

Long-term regional shifts in plant community composition are largely explained by local deer impact experiments.

The fact that herbivores and predators exert top-down effects to alter community composition and dynamics at lower trophic levels is no longer controversial, yet we still lack evidence of the full nature, extent, and longer-term effects of these impacts. Here, we use results from a set of replicated experiments on the local impacts of white-tailed deer to evaluate the extent to which such impacts could account for half-century shifts in forest plant communities across the upper Midwest, USA. We measured species' responses to deer at four sites using 10–20 year-old deer exclosures. Among common species, eight were more abundant outside the exclosures, seven were commoner inside, and 16 had similar abundances in- and outside. Deer herbivory greatly increased the abundance of ferns and graminoids and doubled the abundance of exotic plants. In contrast, deer greatly reduced tree regeneration, shrub cover (100–200 fold in two species), plant height, plant reproduction, and the abundance of forbs. None of 36 focal species increased in reproduction or grew taller in the presence of deer, contrary to expectations. We compared these results to data on 50-year regional shifts in species abundances across 62 sites. The effects of herbivory by white-tailed deer accurately account for many of the long-term regional shifts observed in species' abundances (R2 = 0.41). These results support the conjecture that deer impacts have driven many of the regional shifts in forest understory cover and composition observed in recent decades. Our ability to link results from shorter-term, local experiments to regional long-term studies of ecological change strengthens the inferences we can draw from both approaches.

Effect of grazing on the population of Matteuccia struthiopteris at the southern limit of its distribution in Europe

AbstractWe investigated the impact of deer on an isolated marginal population of Matteuccia struthiopteris and on its plant community in the northern Apennines, where in recent decades the species has decreased dramatically. Our experiment was based on a 6‐year before and after control impact (BACI) design, comparing plots with deer grazing and plots where deer were excluded. Exclusion of grazing interacted with years, increasing the size of existing plants and favoring production of sporophylls. The yearly sequence of increase and decline of ramets and sterile leaves followed the same pattern in the two treatments. This indicated that their annual variation in growth depended on the sequence of more and less favorable years. Few and short plants were associated with grazing, whereas tall plants, shrubs, and tree regeneration were associated with fenced plots. The few plants to persist and dominate on heavily grazed areas were Oxalis acetosella and Cardamine species, while the genus Rubus and tree saplings were grazing‐sensitive species in this forest. Tall herbaceous species increased in size in the fenced areas, however, M. struthiopteris drew more advantage in terms of growth of leaves, showing greater cover than other species. Thus, deer grazing is becoming a threat for the survival of M. struthiopteris in southern Europe where it is already threatened in the long term by climate change.

Long-term consequences of invasive deer on songbird communities: Going from bad to worse?

Although we understand many initial effects of invasive deer on songbirds, we do not yet understand how their longer-term effects unfold. We looked for such potential long-term effects on songbirds in the context of an archipelago where deer were introduced over a century ago. Initial data consist of vegetation plots and songbird point-counts on 57 islands in Haida Gwaii (British Columbia, Canada) taken in 1989 when the impacts of introduced deer lacking predators had already developed for >50 years. Twenty years later, we surveyed these islands using the same methods. To isolate the effects of deer, we compare results to nearby islands never colonized by deer and assess how canopy birds have fared relative to understory birds. We also compare responses between islands of “moderate deer impact” where the understory vegetation was only moderately depleted by deer in 1989 and those with “severe deer impact” where understory vegetation was strongly depleted even in 1989. In 1989 all islands with deer were impoverished in songbirds that depend on understory vegetation, but the moderate impact islands still had richer and more abundant understory forest-bird communities than found on severe impact islands. Islands with the fewest deer impacts in 1989 were small and isolated from sources of deer colonization. By 2009, severe deer impacts extended to islands that were initially less affected by deer. The severity of impacts also increased even on islands that had been dramatically affected by 1989. Declines in bird abundance occurred before declines in bird diversity. These results support the need for actions by wildlife managers to curtail deer impacts as soon as these become evident, especially in reserves and protected areas that lack hunters and other deer predators.

The impact of Sika deer on vegetation in Japan: setting management priorities on a national scale.

Irreversible shifts in ecosystems caused by large herbivores are becoming widespread around the world. We analyzed data derived from the 2009-2010 Sika Deer Impact Survey, which assessed the geographical distribution of deer impacts on vegetation through a questionnaire, on a scale of 5-km grid-cells. Our aim was to identify areas facing irreversible ecosystem shifts caused by deer overpopulation and in need of management prioritization. Our results demonstrated that the areas with heavy impacts on vegetation were widely distributed across Japan from north to south and from the coastal to the alpine areas. Grid-cells with heavy impacts are especially expanding in the southwestern part of the Pacific side of Japan. The intensity of deer impacts was explained by four factors: (1) the number of 5-km grid-cells with sika deer in neighboring 5 km-grid-cells in 1978 and 2003, (2) the year sika deer were first recorded in a grid-cell, (3) the number of months in which maximum snow depth exceeded 50 cm, and (4) the proportion of urban areas in a particular grid-cell. Based on our model, areas with long-persistent deer populations, short snow periods, and fewer urban areas were predicted to be the most vulnerable to deer impact. Although many areas matching these criteria already have heavy deer impact, there are some areas that remain only slightly impacted. These areas may need to be designated as having high management priority because of the possibility of a rapid intensification of deer impact.