As protected areas become more accessible via transportation networks, fragmentation, and encroachment from the borders, carnivores in these areas frequently decline. To counter these pressures, patrolling and active wildlife enforcement are widely accepted as fundamental conservation strategies. Using the case example of Khao Yai National Park (KYNP) and data from a camera trap survey, we modeled and evaluated the effectiveness of ranger stations in reducing human access and illegal activities, and in increasing prey and predator presence. This type of data and analysis is needed to monitor and evaluate enforcement effectiveness and develop adaptive management strategies. At KYNP, we used camera‐trapping data as a proxy to evaluate whether or not a positive impact of ranger stations on wildlife distribution could outweigh edge effects from human disturbance. We assessed factors affecting the distribution of poachers and wildlife using Maxent. Our analysis was based on 217 camera trap locations (6260 trap nights) and suggests that ungulates and poachers persist nearby ranger stations. Rangers should increase patrolling efforts of border areas; however, increasing wildlife patrolling in inaccessible areas with mobile range units may be more effective than establishing more ranger stations along park boundaries. 相似文献
Site occupancy models that account for imperfect detection of species are increasingly utilized in ecological research and wildlife monitoring. Occupancy models require replicate surveys to estimate detection probability over a time period where the occupancy status at sampled sites is assumed closed. Unlike mark–recapture models, few studies have examined how violations of closure can bias occupancy estimates. Our study design allowed us to differentiate among two processes that violate the closure assumption during a sampling season: 1) repeated destructive sampling events that result in either short‐ or long‐term site avoidance by the target species and 2) sampling occurring over a time period during which non‐random movements of the target species result in variable occupancy status. We used dynamic occupancy models to quantify the potential bias in occupancy estimation associated with these processes for a terrestrial salamander system. Our results provide strong evidence of a systematic decrease in salamander occupancy within a field season. Chronic disturbance due to repeated searches of natural cover objects accelerated natural declines in species occurrence on the forest surface as summer progressed. We also observed a strong but temporary disturbance effect on salamander detection probability associated with repeated sampling within a 24‐h. period. We generalized our findings by conducting a simulation to evaluate how violations of closure can bias occupancy estimates when local extinction occurs within a sampling season. Our simulation study revealed general sensitivity of estimates from single‐season occupancy models to violations of closure, with the strength and direction of bias varying between scenarios. Bias was minimal when extinction proba bility or the number of sample occasions was relatively low. Our research highlights the importance of addressing closure in occupancy studies and we provide multiple solutions, using both design‐ and model‐based frameworks, for minimizing bias associated with non‐random changes in occupancy and repeated sampling disturbances. 相似文献
Estimation of site occupancy rates when detection probabilities are <1 is well established in wildlife science. Data from multiple visits to a sample of sites are used to estimate detection probabilities and the proportion of sites occupied by focal species. In this article we describe how site occupancy methods can be applied to estimate occupancy rates of plants and other sessile organisms. We illustrate this approach and the pitfalls of ignoring incomplete detection using spatial data for 2 aquatic vascular plants collected under the Upper Mississippi River's Long Term Resource Monitoring Program (LTRMP). Site occupancy models considered include: a naïve model that ignores incomplete detection, a simple site occupancy model assuming a constant occupancy rate and a constant probability of detection across sites, several models that allow site occupancy rates and probabilities of detection to vary with habitat characteristics, and mixture models that allow for unexplained variation in detection probabilities. We used information theoretic methods to rank competing models and bootstrapping to evaluate the goodness-of-fit of the final models. Results of our analysis confirm that ignoring incomplete detection can result in biased estimates of occupancy rates. Estimates of site occupancy rates for 2 aquatic plant species were 19–36% higher compared to naive estimates that ignored probabilities of detection <1. Simulations indicate that final models have little bias when 50 or more sites are sampled, and little gains in precision could be expected for sample sizes >300. We recommend applying site occupancy methods for monitoring presence of aquatic species. 相似文献
ABSTRACT To investigate the role of black-backed jackals (Canis mesomelas) as predators, we studied diet, prey selection, and predation impact of jackals on 2 game ranches in South Africa that differed in ungulate diversity and biomass. Results showed that large (>15 kg) ungulate species dominated jackal diets throughout the year on both the less diverse (range of ingested biomass across seasons = 39–78%) and more diverse (26–69%) game ranch. Other important food items included medium-sized mammals (1–3 kg; 1–26%) and fruit (2–69%), whereas small mammals comprised 3–11% of ingested biomass across seasons on both sites. Jackals were not random in consumption of ungulates, and consumption patterns suggested jackals actively hunted certain species rather than consumed them as carrion. During ungulate birthing periods, jackals consumed almost exclusively those ungulate species that were hiders (i.e., fawns were hidden in tall vegetation away from herd) regardless of ungulate densities, suggesting that primarily fawns were preyed upon. Among hiders, there was a negative relationship (P = 0.01) between body size and percent of population consumed by jackals, indicating smaller species were more susceptible than larger species to jackal predation. Consequently, springbok (Antidorcas marsupialis) were always selected over other ungulate species on both sites, and this species was the most impacted by jackal predation. In contrast, ungulate species that were followers (i.e., fawns immediately followed mothers within protection of the herd) were scarcely or not at all consumed by jackals, regardless of body size or density. Medium-sized mammals were selectively consumed over ungulates, and there was a negative relationship (P < 0.01) between consumption of berries and ungulates, indicating alternative food resources influenced consumption of ungulates on our study sites. Our results will help wildlife managers in Africa identify ungulate species susceptible to jackal predation, and can be used to develop management strategies for reducing jackal predation in areas where it is problematic. 相似文献
Aim To understand the community structure of mountain ungulates by exploring their niche dynamics in response to sympatric species richness. Location Ladakh and Spiti Regions of the Western Indian Trans‐Himalaya. Methods We used the blue sheep Pseudois nayaur, a relatively widely distributed mountain ungulate, as a model species to address the issue. We selected three discrete valleys in three protected areas with similar environmental features but varying wild ungulate species richness, and studied blue sheep’s diet and habitat utilization in them. Habitat variables such as slope angle, distance to cliff and elevation at blue sheep locations were recorded to determine the habitat width of the species. Faecal pellets were collected and microhistological faecal analysis was carried out to determine the diet width of blue sheep in the three areas with different ungulate species richness. Blue sheep’s niche width in terms of habitat and diet was determined using the Shannon’s Index. Results The habitat width of blue sheep had a negative relationship with the number of sympatric species. However, contrary to our expectation, there was a hump‐shaped relationship between blue sheep’s diet width and the sympatric species richness, with the diet width being narrower in areas of allopatry as well as in areas with high herbivore species richness, and the greatest in areas with moderate species richness. Main conclusions We suspect that the narrow diet width in allopatry is out of choice, whereas it is out of necessity in areas with high herbivore species richness because of resource partitioning that enables coexistence. We suggest that interactions with sympatric species lead to niche adjustment of mountain ungulates, implying that competition may play a role in structuring Trans‐Himalayan mountain ungulate assemblages. Given these results, we underscore the importance of including biotic interactions in species distribution models, which have often been neglected. 相似文献
Ecology of Asia's smallest ungulate, the Indian chevrotain or mouse deer (Moschiola indica), has been poorly assessed. We used camera-trapping data to investigate habitat use of mouse deer in Mudumalai Tiger Reserve. Presence/absence data, collected under a systematic sampling framework, were used to test a priori hypotheses incorporating covariates believed to influence mouse deer occurrence and detection. The average occupancy rate of mouse deer in the study area was 0.56 (SE?=?0.22) with a low detection probability (0.29, SE?=?0.14). Model selection indicated that presence of moist bamboo brakes positively influenced while percent leaf litter negatively influenced mouse deer occupancy. Placement of camera-traps along narrow trails positively influenced detection probability of mouse deer. Future conservation efforts in India should focus on preservation of bamboo vegetation and dense forest cover which provide refuge for the mouse deer. Our results illustrate that occupancy can be suitable for monitoring elusive, forest dwelling, small ungulates; however, caution is needed when applying these models on small ranging species, as our study identifies the limitations in our survey design and its improvement for future monitoring which are applicable for similar-sized species across a range of habitats. 相似文献
Small rodents are prominent seed predators, but they also favour plant recruitment as seed dispersers. The direct interactions of ungulates on plants are more one‐sided and negative, as they mainly reduce plant recruitment through predation on seeds and seedlings. The effects of small rodents and ungulates on plant recruitment have been considered and studied as independent episodes within plant regeneration cycles. However, ungulate–rodent interactions and their potential effects on plant regeneration have not been considered so far. A number of studies have recently documented ungulate effects on the abundance, diversity and spatial distribution of small rodents. Here, we hypothesize that ungulates may also affect rodent seed dispersal behaviour. We monitored acorn dispersal by small rodents (Mus spretus and Apodemus sylvaticus) in oak woodlands with and without exclosures for large ungulates, mainly red deer, Cervus elaphus, and wild boar, Sus scrofa. The study was carried out in a typical Mediterranean Holm oak, Quercus ilex, forest throughout the acorn fall season in 2003 and 2004. We found that, in both years, the proportion of acorns cached and not recovered in the short‐term was, on average, lower in the presence (1.4%) than in the absence (19.9%) of ungulates. Acorn dispersal distances were not affected by ungulate presence in either year. However, ungulates had an effect on the spatial distribution of dispersed seeds; rodents apparently avoided shrubs as caching sites in both years. This result was interpreted as a behavioural response to reduce the risk of cache pilferage by conspecifics, which are closely associated with shrubs in presence, but not in absence, of ungulates. Potential effects of different densities of rodents or predators were discarded, as none of them differed between the areas with and without ungulates. The present study found significant interactions between heterospecific seed and seedling consumers that had been considered as independent episodes within tree regeneration cycles. As a result of such interactions, ungulates may have negative indirect effects on oak recruitment by reducing (1) acorn caching frequency, and (2) the proportion of acorns cached under shrubs, key nurse‐plants for the establishment of Holm oak seedlings in Mediterranean areas. 相似文献
Ungulate game damage to growing forest stock is recognised as being part of a larger landscape-forest-ungulate-human problem to be tackled on a landscape as well as a forest scale. Whether ungulate impacts are seen as “damage” or not depends on the targets of the different land users. Possibilities for a flexible, integrated pattern of ungulate, forest, hunting and landscape management are highlighted.
The impacts of forestry practices on food supply and food-independent settling stimuli for ungulates affect (1) the habitat quality, (2) the density, structure and dynamics of wildlife stocks, (3) the predisposition of forest to game damage, and (4) the scale of game damage that arises. Though silvicultural measures are seen to be of prime importance in controlling game damage, they alone cannot sustainably solve the problems of wildlife management; complementary inputs are required from all stakeholders – foresters, hunters, farmers, tourist authorities, conservationists, regional planning authorities and local communities – with plans coordinated over large enough regions to be relevant for the game species of interest.
The management tools for steering ungulate behaviour and forest-ungulate interactions derive from field research. However, communication of results to stakeholders appears to be a major weakness. Suggestions for improving collaboration between stakeholders and researchers are presented, along with future research needs. 相似文献
There is intense interest in basic and applied ecology about the effect of global change on current and future species distributions. Projections based on widely used static modeling methods implicitly assume that species are in equilibrium with the environment and that detection during surveys is perfect. We used multiseason correlated detection occupancy models, which avoid these assumptions, to relate climate data to distributional shifts of Louisiana Waterthrush in the North American Breeding Bird Survey (BBS) data. We summarized these shifts with indices of range size and position and compared them to the same indices obtained using more basic modeling approaches. Detection rates during point counts in BBS surveys were low, and models that ignored imperfect detection severely underestimated the proportion of area occupied and slightly overestimated mean latitude. Static models indicated Louisiana Waterthrush distribution was most closely associated with moderate temperatures, while dynamic occupancy models indicated that initial occupancy was associated with diurnal temperature ranges and colonization of sites was associated with moderate precipitation. Overall, the proportion of area occupied and mean latitude changed little during the 1997–2013 study period. Near‐term forecasts of species distribution generated by dynamic models were more similar to subsequently observed distributions than forecasts from static models. Occupancy models incorporating a finite mixture model on detection – a new extension to correlated detection occupancy models – were better supported and may reduce bias associated with detection heterogeneity. We argue that replacing phenomenological static models with more mechanistic dynamic models can improve projections of future species distributions. In turn, better projections can improve biodiversity forecasts, management decisions, and understanding of global change biology. 相似文献
The impacts of conflict on nature are devastatingly adverse but differ widely in different socio-economic-political regimes. Armed conflict often facilitates illegal plunder and unsustainable use of natural resources. We studied the response of mammals in Ripu (605.27 sq.km, westernmost part of Manas Tiger Reserve) Reserved Forest (RF) in Assam, India that suffers prolonged anthropogenic pressures due to armed conflict instigated by social unrest. We used standard single-season occupancy models using sign survey to assess factors affecting the space use of mammals. Our study revealed that Ripu RF has a high proportion of area occupied by prey species of large carnivores. Asian elephant, barking deer, and wild pig occupied most of the habitat, whereas gaur, sambar and spotted deer restricted themselves to selected patches. The probability of a site being occupied by the majority of ungulates declines with an increase in anthropogenic activities, including distance to human settlement (measure of prolonged disturbance) and an increase in the proportion of secondary degraded forest. Common leopard was found to be positively associated with prey occupancy and increase in semievergreen and moist-mixed deciduous forest. Our ground efforts to strengthen community patrolling and operational execution of various alternative livelihoods has helped to improve the economic condition of patrolling staff. Strategic implementation of law enforcement could support dispersal of tigers from Phibsoo Wildlife Sanctuary (Bhutan), potentially linked to the larger tiger and elephant landscape far west (Buxa Tiger Reserve in West Bengal) in the Terai region of India. Various community-based conservation initiatives and strategies with sustained support from various agencies, including national, international, and local bodies, is required to restore this critical habitat. 相似文献
The abandonment of traditional livestock farming systems in Mediterranean countries is triggering a large-scale habitat transformation, which, in general, consists of the replacement of open grazing areas by woodlands through non-managed regeneration. As a consequence, wild ungulates are occupying rapidly the empty niche left by domestic ungulates. Both types of ungulates represent the main trophic resource for large vertebrate scavengers. However, a comparison of how vertebrate scavengers consume ungulate carcasses in different habitats with different ungulate species composition is lacking. This knowledge is essential to forecast the possible consequences of the current farmland abandonment on scavenger species. Here, we compared the scavenging patterns of 24 wild and 24 domestic ungulate carcasses in a mountainous region of southern Spain monitored through camera trapping. Our results show that carcasses of domestic ungulates, which concentrate in large numbers in open pasturelands, were detected and consumed earlier than those of wild ungulate carcasses, which frequently occur in much lower densities at more heterogenous habitats such as shrublands and forest. Richness and abundance of scavengers were also higher at domestic ungulate carcasses in open habitats. Vultures, mainly griffons (Gyps fulvus), consumed most of the carcasses, although mammalian facultative scavengers, mainly wild boar (Sus scrofa) and red fox (Vulpes vulpes), also contributed importantly to the consumption of wild ungulate carcasses in areas with higher vegetation cover. Our findings evidence that the abandonment of traditional grazing may entail consequences for the scavenger community, which should be considered by ecologists and wildlife managers. 相似文献
The effects of multispecific systems containing both mutualistic and antagonistic interacting organisms on the evolution of plant traits have seldom been analyzed. We studied the selection exerted by several species of herbivores and pollinators in three populations of Hormathophylla spinosa (Cruciferae) in the Sierra Nevada (Spain) over 4 yr by using path analyses and structural equation modeling (SEM). The main selective pressures in our study sites were ungulates and pollinators. However, the importance of each kind of interacting organism differed among populations. Our results indicate a selection mosaic among populations of H. spinosa in the Sierra Nevada caused by the spatial variation in the relative importance of different interactions as selective pressures. We found two main selective scenarios, depending on the presence or absence of ungulates. In the populations with low ungulate pressure, there was positive phenotypic selection in flower number per plant and in flower density (mediated by nectarivorous pollinators). In the two populations with high ungulate pressure, there was a strong positive, ungulate-mediated selection in thorn density. Our results suggest that the application of SEM to several populations simultaneously monitored might help to isolate the major selection pressures on local populations and identify potential differences in selection among populations, becoming a useful exploratory approach to study the geographical variation of selection in complex systems. 相似文献
Ungulate abundance has increased dramatically worldwide, having strong impacts on ecosystem functioning. High ungulate densities can reduce the abundance, diversity and/or body condition of small mammals, which has been attributed to reductions in cover shelter and food availability by ungulates. The densities of wild ungulates have increased recently in high-diversity Mediterranean oak ecosystems, where acorn-dispersing small rodents are keystone species. We analysed experimentally ungulate effects on seed-dispersing rodents in two types of oak woodland: a forest with dense shrub layer and in dehesas lacking shrubs. Ungulates had no significant effects on vegetation structure or rodent body mass, but they reduced dramatically rodent abundance in the lacking-shrub dehesas. In the forest, ungulates modified the spatial distribution and space use of rodents, which were more concentrated under shrubs in the presence than in the absence of ungulates. Our results point to the importance of shrubs in mediating ungulate–rodent interactions in Mediterranean areas, suggesting that shrubs serve as shelter for rodents against ungulate physical disturbances such as soil compaction, trampling or rooting. Holm oak seedling density was reduced by ungulates in dehesa plots, but not in forests. Acorn consumption by ungulates may reduce oak recruitment to a great extent. Additionally, we suggest that ungulates may have a negative effect on oak regeneration processes by reducing the abundance of acorn-dispersing rodents. Given that shrubs seem to mediate ungulate effects on acorn dispersers, controlled shrub encroachment could be an effective alternative to ungulate population control or ungulate exclusion for the sustainability of the high-diversity Mediterranean oak ecosystems. 相似文献
Insects and ungulates co‐occur in grasslands, often feeding on the same plants at the same time and potentially having interactive effects on plant growth. Further, ungulate–insect interactions may differ between native ungulate guilds and domesticated cattle. Despite the prevalence of insects and ungulates in native grasslands, experiments simultaneously manipulating the densities of both these groups are rare. Using large, replicated paddocks, as well as insecticide application, we restricted access to vegetation by each group of herbivores. We also manipulated the species identity of the ungulate assemblage, allowing us to determine whether there are differential effects between native ungulate guilds (bison, elk and deer) and cattle on plant biomass. We found interactive effects of insect and ungulate herbivores on root growth. When insects were suppressed, both native ungulates and cattle caused an approximate doubling of root biomass. However, this stimulatory effect of ungulate grazing was eliminated when insects were also present. In contrast, neither insects nor ungulates had significant effects on shoot biomass at these densities. As a result, the dominant effects of above‐ground herbivory was on belowground plant growth. We suggest the effects of insect and ungulate assemblages on root biomass appear important in regulating primary production in this grassland and may account for some of the contradictory plant responses to ungulate herbivory in the literature. 相似文献
Large wild ungulates are a major biotic factor shaping plant communities. They influence species abundance and occurrence directly by herbivory and plant dispersal, or indirectly by modifying plant‐plant interactions and through soil disturbance. In forest ecosystems, researchers’ attention has been mainly focused on deer overabundance. Far less is known about the effects on understory plant dynamics and diversity of wild ungulates where their abundance is maintained at lower levels to mitigate impacts on tree regeneration. We used vegetation data collected over 10 years on 82 pairs of exclosure (excluding ungulates) and control plots located in a nation‐wide forest monitoring network (Renecofor). We report the effects of ungulate exclusion on (i) plant species richness and ecological characteristics, (ii) and cover percentage of herbaceous and shrub layers. We also analyzed the response of these variables along gradients of ungulate abundance, based on hunting statistics, for wild boar (Sus scrofa), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Outside the exclosures, forest ungulates maintained higher species richness in the herbaceous layer (+15%), while the shrub layer was 17% less rich, and the plant communities became more light‐demanding. Inside the exclosures, shrub cover increased, often to the benefit of bramble (Rubus fruticosus agg.). Ungulates tend to favour ruderal, hemerobic, epizoochorous and non‐forest species. Among plots, the magnitude of vegetation changes was proportional to deer abundance. We conclude that ungulates, through the control of the shrub layer, indirectly increase herbaceous plant species richness by increasing light reaching the ground. However, this increase is detrimental to the peculiarity of forest plant communities and contributes to a landscape‐level biotic homogenization. Even at population density levels considered to be harmless for overall plant species richness, ungulates remain a conservation issue for plant community composition. 相似文献