High Deer Densities Research Articles

Comparative Analysis of Prickles on Rubus sieboldii (Rosaceae) between Grazed and Ungrazed Areas in Southwestern Shikoku, Japan

Kashima Island (32o57?N, 132o27?E) is a very small island (45.1 ha) in southwestern Shikoku, Japan with a high density (ca. 38.5/km 2 ) of Sika deer ( Cervus nippon ). To examine induced defences of plants against the Sika deer, we conducted morphological analyses of prickles of Rubus sieboldii Blume (Rosaceae) between grazed (Kashima Island) and ungrazed areas (neighbour locations) in southwestern Shikoku. The length and density of prickles on leaves and around stems were measured. The prickles of the plants on Kashima Island were significantly longer and denser than those of the other areas, implying that the increased length and density of prickles were an induced defence of R. sieboldii on Kashima Island.

A review of the population dynamics of mule deer and black‐tailed deer Odocoileus hemionus in North America

Abstract Mule deer and black‐tailed deer Odocoileus hemionus have exhibited marked population fluctuations throughout their range over the past century. The relative contributions of predation, forage availability and weather to observed population changes remain unclear and controversial. We reviewed 48 studies on Odocoileus hemionus survival and predation from the past 30 years and quantified age‐specific vital rates, population growth rates (λ) and causes of mortality. We also evaluated the effect of environmental variables on variation in vital rates and the contribution of age‐specific survival to population growth. Age‐specific survival (ϕ) was the most frequently studied population parameter. Odocoileus hemionus have lower and more variable fawn survival than other ungulate species (ϕsummer = 0.44, CV = 0.42; ϕannual = 0.29, CV = 0.67). Adult female survival conversely appeared to be high and stable throughout the geographical range of the species (ϕannual = 0.84, CV = 0.06). Observed low fawn survival appears to be compensated for by high fecundity rates. Predation was the primary proximate cause of mortality for all age classes, and was an important source of summer fawn mortality and of mortality in multi‐prey, multi‐predator systems. However, predator removal studies suggest that predation is compensatory, particularly at high deer densities, and that nutrition and weather shape population dynamics. We propose three models to explain local population dynamics of Odocoileus hemionus: (i) populations are limited by forage availability and weather; (ii) adult females are limited by forage availability, fawns are limited by forage availability and predation, and population growth is constrained by fecundity and fawn predation; and (iii) large changes in the abundance of predators or alternative prey change predation risk and destabilize population dynamics. Future research should be focused on: the effects of age‐specific survival on population growth; possible interactions between predation, forage availability and weather; and the importance of multiple predator and prey species in shaping the population dynamics of Odocoileus hemionus.

Browsing of sallow (Salix caprea L.) and rowan (Sorbus aucuparia L.) in the context of life history strategies: a literature review

Sallow (Salix caprea L.) and rowan (Sorbus aucuparia L.) constitute small proportions of the deciduous tree volume in Scandinavia, but are highly preferred winter forage for moose and red deer, which occur at historically high densities. Thus, a possible decline of these tree species has been indicated. Against this background, we have reviewed the life histories of relevance for browsing, as well as the basic biology and genetics of sallow and rowan. The species show similarities with respect to short lifespan, small size and sympodial growth pattern, which are risk factors in a browsing context. They also have high juvenile growth rate, important for growing quickly out of reach of browsers. Sallow depends strongly on disturbance for establishment and is more demanding with respect to soil and light conditions than rowan, possibly important for the substantially lower abundance of sallow on the Norwegian Forest Inventory plots. Similarly, the relative recruitment of small size classes of sallow is less than for rowan. Although recruitment is reported to be hampered in wintering areas with high moose or red deer densities, the inventory data, however, dating only back to 1994, do not suggest a general decrease in any of the species. Sallow and rowan saplings show low mortality in moose and deer dominated areas and the species can be characterised as rather resilient to browsing. Of more concern is that browsing can constrain the development of mature rowan and sallow trees locally, with possible consequences for associated epiphytic biodiversity.

Prevalence of Shiga toxin-producing Escherichia coli, Salmonella spp. and Campylobacter spp. in large game animals intended for consumption: Relationship with management practices and livestock influence

Although wild ruminants have been identified as reservoirs of Shiga-toxin producing Escherichia coli (STEC), little information is available concerning the role of Salmonella spp. and Campylobacter spp. in large game species. We evaluated the presence of these pathogens in faeces (N=574) and carcasses (N=585) sampled from red deer (N=295), wild boar (N=333) and other ungulates (fallow deer, mouflon) (N=9). Animal sampling was done in situ from 33 hunting estates during two hunting seasons. Salmonella spp. and Campylobacter spp. strains associated with human campylobacteriosis were infrequently detected indicating that both pathogens had a limited zoonotic risk in our study area. The overall STEC prevalence in animals was 21% (134/637), being significantly higher in faeces from red deer (90 out of 264). A total of 58 isolates were serotyped. Serotypes O146:H- and O27:H30 were the most frequent in red deer and the majority of isolates from red deer and wild boar were from serotypes previously found in STEC strains associated with human infection, including the serotype O157:H7. The STEC prevalence in red deer faeces was significantly higher with the presence of livestock (p<0, 01) where high densities of red deer (p<0.001) were present. To the best of our knowledge, this is the first study reporting the occurrence of Salmonella spp. and STEC in carcasses of large game animals. Furthermore, this study confirmed by pulsed-field gel electrophoresis (PFGE) that cross contamination of STEC during carcass dressing occurred, implying the likelihood of these pathogens entering into the food chain.

Linking direct and indirect pathways mediating earthworms, deer, and understory composition in Great Lakes forests

Ahistorical drivers such as nonnative invasive earthworms and high deer densities can have substantial impacts on ecosystem processes and plant community composition in temperate and boreal forests of North America. To assess the roles of earthworm disturbance, deer, and environmental fac- tors in the understory, we sampled 125 mixed temperate-boreal forest sites across the western Great Lakes region. We utilized structural equation modeling (SEM) to address the hypothesis that earthworm disturbance to the upper soil horizons and selective herbivory by deer are associated with depauperate understory plant communities dominated by graminoid and nonnative species. Evidence of earthworm activity was found at 93 % of our sites and 49 % had high to very high severity earthworm disturbance. The SEM fit the data well and indicated that widespread nonnative earthworm disturbance and high deer densities had similar magnitudes of impact on understory plant communities and that these impacts were partially mediated by environmental characteristics. One-third of the variation in earth- worm disturbance was explained by soil pH, precip- itation, and litter quality. Deer density and earthworm disturbance both increased graminoid cover while environmental variables showed direct and indirect relationships. For example, the positive relationship between temperature and graminoids was indirect through a positive temperature effect on deer density. This research characterizes an integrated set of key environmental variables driving earthworm distur- bance and deer impacts on the forest understory, facilitating predictions of the locations and severity of future change in northern temperate and boreal forest ecosystems.

Acceptability and Conflict Regarding Suburban Deer Management Methods

Natural resource agencies and the public often agree on reasons to manage white-tailed deer (Odocoileus virginianus) in suburban areas; however, there is frequent disparity regarding which deer management method is most acceptable. We surveyed 660 residents around 22 conservation areas in a suburban Illinois county to evaluate the acceptance and the potential for conflict regarding five deer management methods countywide, in urban and rural areas, and in high (≥11 deer/km2) and low (≤9 deer/km2) deer density areas. Archery hunting was the most acceptable method followed by gun hunting, sharpshooting, and fertility control; conducting no deer management was unacceptable (p < .001). Archery hunting and no deer management had the least conflict among residents; fertility control had the most conflict (.001 ≥ p ≤ .010). We recommend managers conduct surveys that incorporate public conflict regarding deer management methods to gain information that may guide education and resolve management disputes.

A model to test how ticks and louping ill virus can be controlled by treating red grouse with acaricide

Ticks are the most important vectors of disease-causing pathogens in Europe. In the U.K., Ixodes ricinus L. (Ixodida: Ixodidae) transmits louping ill virus (LIV; Flaviviridae), which kills livestock and red grouse, Lagopus lagopus scoticus Lath. (Galliformes: Phasianidae), a valuable game bird. Tick burdens on grouse have been increasing. One novel method to reduce ticks and LIV in grouse may be acaricide treatment. Here, we use a mathematical model parameterized with empirical data to investigate how the acaricide treatment of grouse might theoretically control ticks and LIV in grouse. Assuming a situation in which ticks and LIV impact on the grouse population, the model predicts that grouse density will depend on deer density because deer maintain the tick population. In low deer densities, no acaricide treatment is predicted to be necessary because abundances of grouse will be high. However, at higher deer densities, the model predicts that grouse densities will increase only if high numbers of grouse are treated, and the efficacy of acaricide is high and lasts 20 weeks. The qualitative model predictions may help to guide decisions on whether to treat grouse or cull deer depending on deer densities and how many grouse can be treated. The model is discussed in terms of practical management implications.

Roads and supplemental feeding affect home-range size of Slovenian red deer more than natural factors

Most studies on the relationship between home-range size and composition focus on natural factors, whereas effects of anthropogenic factors are poorly understood. I evaluated effects of multiple natural and anthropogenic habitat factors, population density, and sex on the annual home-range size of red deer (Cervus elaphus) in wellpreserved forest areas in the Dinaric Mountains of Slovenia, Europe, based on .11,000 telemetry locations from 17 males and 25 females. Home ranges were 90–2,107 ha and averaged 460 ha. Using a mixed linear model, I estimated that home-range size decreased with increasing 1) red deer density, 2) supplemental feeding intensity, and 3) average annual temperature; 4) home-range size increased as the distance of main roads from the edge of the home range increased; and 5) males had a larger home range than females (580 ha versus 400 ha). These results were explained by effects of food availability (1, 2, and 3), energy expenditure of an individual (4 and 5), intraspecific interactions (1 and 5), and size of unfragmented habitat patches (4) on home-range size. To my knowledge, this is the 1st large mammal study to explicitly show that the density and spatial distribution of roads and supplemental feeding affect home-range size of red deer and that humans can have a greater impact on home-range size and shape than natural habitat factors. Ungulates are often supplementally fed to increase their value to hunters and to reduce forest damage, particularly in Europe; however, this practice can greatly reduce the home-range size, potentially leading to increased disease transmission and competition associated with the higher deer densities around feeding sites, which can result in just the opposite of what was intended.

Survey of Zoonotic Pathogens in White-Tailed Deer on Bald Head Island, North Carolina

Odocoileus virginianus (White-tailed Deer) have become overabundant in many urban and suburban areas, which can cause concern about exposure of humans and pets to zoonotic pathogens. Bald Head Island, NC is a small barrier island that has experienced ongoing residential development since the mid-1980s and has a relatively high deer density (15–17 deer/km2). To address concerns expressed by residents, we screened ≈13% of the White-tailed Deer population for potential zoonotic pathogens. We collected blood from 8 deer in January through March 2008 and 5 deer in January 2009. We tested sera for antibodies to Anaplasma phagocytophilum, Borrelia burgdorferi, and six serovars of Leptospira interrogans; and whole blood samples for Bartonella spp. and B. burgdorferi DNA. All sera were negative for antibodies to L. interrogans; two samples were seropositive for A. phagocytophilum, and one was seropositive for B. burgdorferi. Whole blood PCR results were negative for Bartonella spp. and B. burgdorferi. Continued surveillance for wildlife diseases on Bald Head Island is necessary to determine prevalence of specific pathogens, their impacts on the White-tailed Deer population, and the risk of exposure to humans and pets.

White‐Tailed Deer (Odocoileus virginianus) as a Potential Sentinel for Human Lyme Disease in Indiana

We assessed the potential of white-tailed deer (WTD) (Odocoileus virginianus) to be a sentinel for human cases of Lyme disease (LD) in Indiana using location data from a 3-year survey of approximately 3400 hunted deer with associated tick Ixodes scapularis and Borrelia burgdorferi (Bb) data. Data on human LD cases at the county level were obtained from the Indiana Department of Health. All data were assigned to county centroids to match the resolution of the LD data before creating optimized trend surfaces for LD incidence, hunted deer count, Ixodes scapularis and Bb prevalence. To determine whether LD was spatially associated with the areas of high densities of deer, deer with Ixodes scapularis and deer with ticks infected with Bb, we used spatial analysis with distance indices (SADIE). The SADIE analysis found significant spatial association between LD and the distribution of three organismal predictor variables, that is, WTD, Ixodes ticks and Bb. Lyme disease incident rate varied between 0.08 cases per 10,000 habitants (Johnson county) and 5.9 cases per 10,000 habitants (Warren county). In conclusion, WTD can be used as an accurate and cost-effective sentinel for human LD. This method will permit public health workers to identify potentially endemic areas independently of human case reports.

An experimental study of how variation in deer density affects vegetation and songbird assemblages of recently harvested boreal forests

Intense browsing by abundant large herbivores can threaten the ecological integrity of ecosystems by inducing modifications in the structure and composition of vegetation that trigger trophic cascades affecting plant and animal communities. We investigated the relationships between density of white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)), forest succession after clear-cut, and songbird communities on Anticosti Island, Quebec, Canada. We hypothesized that lower deer densities would alter the trajectory of forest succession after clear-cutting and lead to a rapid recovery of habitat attributes favorable to songbirds associated with a dense complex shrub layer. Six years after establishing a controlled browsing experiment (0, 7.5, 15, and &gt;27 deer·km–2) in recent clearcuts, reducing deer densities ≤7.5 deer·km–2initiated the restoration of balsam fir ( Abies balsamea (L.) Mill.) forests and increased the regeneration of paper birch ( Betula papyrifera Marshall). Increasing birch ground cover from 10% to 20% increased songbird total abundance, species richness, and diversity by 17%, 39%, and 31%, respectively. Alder Flycatcher (Empidonax alnorum Brewster, 1895) was only present at ≤7.5 deer·km–2and strongly associated with birch regeneration. The regeneration of browse-resistant plants such as white spruce ( Picea glauca (Moench) Voss) in some areas at high deer density favored the maintenance of many shrub-dependent songbirds but also species usually associated with forest canopy. Active management of deer populations in Canadian harvested boreal forests will mitigate losses in vegetation and songbirds caused by over-browsing.

Deer herbivory as an important driver of divergence of ground vegetation communities in temperate forests

Ungulate herbivory can fundamentally affect terrestrial vegetation at the landscape and regional levels, but its impact has never been analyzed from meta‐community perspectives. Here, we study a meta‐community of forest ground‐layer plants in a warm‐temperate region along a clear gradient of deer density interplaying with gradients of other environmental factors (forest type, sky openness and topographic wetness). Canonical corresponding analysis showed that deer density was the most important determinant of species distributions. These distributions conformed to a two‐directional filtering model, which selects for competitive species at low deer density but favours herbivory‐tolerant plants at high deer density, with these two directions counterbalancing each other when herbivory is intermediary. This resulted in a bi‐directionally nested meta‐community, in which local species richness was highest at intermediate levels of deer density, conforming also to the intermediate disturbance hypothesis. Our results suggest that herbivory can be the most important driver of meta‐community structure in mesic systems; this contrasts with the results of earlier studies conducted in harsh environments, where species sorting by abiotic factors at early life stages reduced the role of biotic interactions, including herbivory.

Emergence of cooperative behaviours in the management of mobile ecological resources

Cooperation at neighbourhood and landscape scale is frequently advocated as a means of improving the management of ecological resources. Such management often involves multiple agents and takes place in spatially structured landscapes where interactions between management actions are mediated via spatio-temporal dynamics of the managed resource. Evolutionary game theory has sought mechanisms to explain the emergence of cooperation among selfish individuals in these complex socio-ecological contexts, and spatial implementations of standard games have shown that the development and persistence of cooperation is affected by spatial structure. However, existing game theoretic models do not incorporate the dynamics of the managed resource or cross-linkages between resource dynamics and management actions and payoffs. We use a spatial agent-based modelling approach to investigate how ecological dynamics, payoff structures, and their interdependencies, influence the emergence and persistence of cooperative behaviours in the management of red deer (Cervus elaphus) in Scotland. Simulation results for landscapes comprised of agents with (i) only sporting, and (ii) only biodiversity management objectives show significant differences in the spatial patterns of management action and cooperative behaviour which emerge as limit cycle attractors. Compact clusters of cooperative agents arise in the sporting scenario, culling at low intensity to maintain advantageously high deer densities. Cooperative behaviour in the biodiversity scenario emerges as a context-dependent function of deer density in filament-like structures along the boundaries between linear regions of high or low culling intensity. These findings suggest that mechanisms driving the emergence of cooperative behaviours can be complex and that the opportunities for, and benefits derived from, cooperation are likely to depend critically on both the management objectives and dynamics of the resource.

Influence of habitat features and hunter behavior on white‐tailed deer harvest

AbstractSport hunting may help in controlling cervid populations over large areas. As with natural predators, several environmental factors can influence sport harvest. A better understanding of the environmental variables that limit the efficiency of sport hunting could provide guidelines for more efficient wildlife management using hunting. We studied white‐tailed deer (Odocoileus virginianus) hunting on a high deer density island where hunting was the sole form of predation. Our objective was to study the behavior of sport hunters and determine the habitat characteristics (e.g., abundance of deer forage, visibility of the deer from the hunter's point of view, and accessibility of the territory to hunters) that are associated with a successful harvest. We collected movements and harvest site location data from 477 hunters equipped with handheld Global Positioning System (GPS) units. Harvest sites were visited and characterized, along with a paired random site, to determine the environmental conditions associated with a successful hunt. We also developed a model to predict the daily number of deer seen by hunters considering weather conditions, hunter characteristics (e.g., age, experience), and date of hunting. We used the mean number of deer seen per hunter per day as a relative index of local density in each hunted territory. At both the site and landscape scales, the combination of visibility and access had a positive effect on the distribution of harvested deer. Habitat types with less visual obstruction from vegetation enabled hunters to see more deer in a given day. At the site scale, harvested deer were located in areas with a lower density of access routes compared to areas where hunters travelled throughout the day. Using an innovative approach of studying hunter behavior with GPS technology, digital maps, and questionnaires, we highlighted the factors associated with hunter success. Our study suggests that habitat characteristics could be modified to increase harvest by improving accessibility and visibility near roads. Creating openings in mature and regenerating forest near access roads could make sport hunting a more efficient management tool, but the potential impact of increased forage availability in forest openings should not be overlooked. © 2012 The Wildlife Society.

Variation in utilization of young leaves by a swallowtail butterfly across a deer density gradient

Phytophagous insects can be affected by plant trait-mediated indirect effects of large herbivores, but little is known regarding how these effects change in response to different densities of large herbivores. To assess the response of an insect to plant qualitative change, the response of a woody vine (Aristolochia kaempferi) to browsing by sika deer (Cervus nippon) and utilization of young leaves by a swallowtail butterfly (Byasa alcinous) were investigated across a deer density gradient. Natural and simulated deer browsing stimulated the regrowth of A. kaempferi and improved nutritional and physical quality of leaves. Young leaves were frequently observed in areas with high deer densities. The proportion of young leaves among the leaves selected for oviposition was higher than their proportion of the total number of leaves. In areas with low deer densities, the utilization of young leaves by B. alcinous increased linearly with deer density, whereas in areas with high deer densities, the utilization of young leaves was around 90%.

Beyond the browse line: complex cascade effects mediated by white‐tailed deer

In many ecosystems, browsing of large mammals can affect plant species compositions. However, much less is known about potential above‐ and below‐ground trophic interactions of large browsing mammals. This study focused on the direct and indirect effects of browsing on trophic and abiotic interactions within forest ecosystems. To quantify above‐ and below‐ground cascade effects, white‐tailed deer have been excluded for over 18 years from three 4‐ha plots, which were paired with same sized deer access plots. Our results demonstrate complex direct and indirect cascade effects on forest food webs. Deer exclusion directly altered woody species composition and significantly increased shrub and sapling density. Above‐ground cascade effects include greater leaf litter accumulation and higher arthropod density and biomass within the exclosures. Below‐ground indirect effects include significant decrease in soil nutrients, and higher arbuscular mycorrhizal fungal inoculum potential in the exclosures. Because ecosystems have finite resource availability, high deer density may imbalance the system by redirecting resources toward maintaining deer biomass at the expense of multiple trophic levels throughout the forest community. Both complex bottom up and top down trophic cascade effects demonstrated largely unidirectional negative responses suggesting that high deer density has reduced the biodiversity of the forest community.

Wildflowers Susceptible to Deer Damage in North Florida

One sure way to prevent deer damage to your landscape is to choose plants that deer do not like to eat. Unfortunately, deer foraging preferences vary geographically and studies conducted with captive deer aren’t always accurate. So UF/IFAS wildlife researchers investigated the foraging preference of wild white-tailed deer at two sites in Gadsden County with high deer densities for two years. Of 11 wildflowers tested, four were very susceptible to browsing: fringeleaf tickseed, Florida tickseed, coastalplain tickseed, and orange coneflower. This 4-page fact sheet was written by Holly K. Ober, Lucas W. DeGroote, James H. Aldrich, Jefferey G. Norcini, and Gary W. Knox, and published by the UF Department of Wildlife Ecology and Conservation, December 2011. WEC315/UW360: Wildflowers Susceptible to Deer Damage in North Florida (ufl.edu)

Ecology and management of white‐tailed deer in a changing world

Due to chronic high densities and preferential browsing, white-tailed deer have significant impacts on woody and herbaceous plants. These impacts have ramifications for animals that share resources and across trophic levels. High deer densities result from an absence of predators or high plant productivity, often due to human habitat modifications, and from the desires of stakeholders that set deer management goals based on cultural, rather than biological, carrying capacity. Success at maintaining forest ecosystems require regulating deer below biological carrying capacity, as measured by ecological impacts. Control methods limit reproduction through modifications in habitat productivity or increase mortality through increasing predators or hunting. Hunting is the primary deer management tool and relies on active participation of citizens. Hunters are capable of reducing deer densities but struggle with creating densities sufficiently low to ensure the persistence of rare species. Alternative management models may be necessary to achieve densities sufficiently below biological carrying capacity. Regardless of the population control adopted, success should be measured by ecological benchmarks and not solely by cultural acceptance.

Live-trapping and bovine tuberculosis testing of free-ranging white-tailed deer for targeted removal

Context Significant efforts have been made in Michigan, USA, to reduce the prevalence of bovine tuberculosis (TB) in free-ranging white-tailed deer (Odocoileus virginianus) over the past 15 years. Since 2002, however, prevalence has changed little, prompting the need for new control strategies. Aims In January–March of 2007 and 2008, a trap–test–cull project was conducted on an 11 000-ha property in the north-eastern Lower Peninsula of Michigan. The objectives were to assess the feasibility of live-trapping and testing white-tailed deer for TB as a means for targeted removal and estimate the cost of this effort. Methods Live-trapped deer were ear-tagged and a blood sample was drawn for use with the CervidTB STAT-PAK (commonly called Rapid Test) for TB diagnosis in the field. Deer testing negative were released, whereas deer testing positive were euthanised to confirm blood-test results via bacterial culture. Key results In all, 762 (741 with known sex and age) individual deer were captured and tested for TB. Adults comprised 59% (437 of 741) of the captures. Eight (1.8%) adults were positive on the blood test; six of eight (1.4% of adults) were confirmed TB positive via bacterial culture. Estimated TB prevalence in the present study was 2.5% (adjusted for Rapid Test sensitivity of 56%), being lower than what would be expected on the basis of routine hunter-harvest surveillance for this site which has yielded prevalence rates from 3.4% to 4.8%. Results demonstrated the ability to trap and test a substantial number of deer given high deer densities (16–20 deer per km2), availability of traps and abundant workers. The 2-year project cost a total of ~US$228 000, or US$38 000 per culture-positive animal. Conclusions Because of the cost and effort involved, a project such as the present one applied to Michigan’s larger TB-management area (148 018 ha) is not feasible. Implications If the efficiency and effectiveness of a trap–test–cull project could be improved by vaccinating test-negative animals, should a vaccine be approved for use in free-ranging white-tailed deer, a trap–test–cull project applied on a scale similar to the present study may prove beneficial by possibly reducing disease transmission, in addition to removing TB-positive animals.

MANDIBULAR OSTEOMYELITIS IN RED DEER (CERVUS ELAPHUS HISPANICUS) AND FALLOW DEER (DAMA DAMA): OCCURRENCE AND ASSOCIATED FACTORS IN FREE-LIVING POPULATIONS IN SOUTHERN SPAIN

The prevalence of mandibular osteomyelitis, which results in a condition called lumpy jaw, and factors associated with its occurrence were investigated in syntopic free-living populations of red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) in Spain. The study material consisted of 3,586 mandibles from 2,548 red deer and 1,038 fallow deer shot during sport hunting, herd management culls, and programs for population control between 1988 and 1997 (period 1) and 2002 and 2009 (period 2) in eastern Sierra Morena, southern Spain. Disease prevalence ranged from 0.36% to 10.91% among age groups. Older animals were significantly more likely to be affected than younger ones. Red deer stags had higher prevalence than other groups. There was a significantly higher prevalence in period 1, probably associated with differences in climatic and population conditions. High population densities of female red deer contributed significantly to occurrence of disease. Intensive herd management and poor environmental conditions were considered risk factors that increased susceptibility to disease. The study of this affliction could be useful for monitoring general herd welfare and ecologic changes in Mediterranean ecosystems.