Phytomass utilization and deposition of feces by ungulates on steppe pastures of eastern Mongolia

The amount of phytomass removed by a complex of livestock (horses, cattle, sheep, and goats) and wild ungulates (Mongolian gazelle Procapra gutturosa Pall.) grazing in plain and mountain pastures of eastern Mongolia has been estimated by taking account of feces deposited by these animals. The results show that at an animal density of up to 30 head/km², the total annual amount of feces reaches 140 kg/ha (dry weight), with the greater part (up to 90 kg/ha) being deposited by horses. The contribution of Mongolian gazelles in some pastures reaches 20–40 kg/ha per year. Decomposition of feces proceeds very slowly, with the annual loss of their weight averaging only 9–12%. This is evidence for gradual accumulation of nondecomposed matter in the soil. The removal of phytomass by the complex of ungulates, calculated from the amount of feces with regard to their annual loss and forage digestibility, varies in different grazing areas from 240 to 400 kg/ha (25–60% of the total aboveground phytomass). The greatest amount of phytomass is utilized by horses, reaching 200 kg/ha (13%), and Mongolian gazelles utilize up to 86 kg/ha per year. In the growing season, ungulates remove no more than 11–16% of the total aboveground phytomass. It is concluded that the impact of total ungulate stock does not impair the productivity of vegetation in the pastures studied.     

Nowhere to run: semi-permeable barriers affect pronghorn space use

Animal movement can mediate the ecological consequences of fragmentation; however, barriers such as fences, roads, and railways are becoming a pervasive threat to wildlife. Pronghorn (Antilocapra americana) habitat in western North America has been fragmented by roads, railways, and fences. Although pronghorn are sensitive to barriers, neither the relative permeability of different barriers to crossing nor their influence on space use have been quantified. We used a large global positioning system (GPS)-collar dataset of pronghorn (n = 1,010 animal-years) in Wyoming, USA, to first quantify the likelihood that pronghorn cross each of 5 different anthropogenic barriers, including fences, county roads, railroads, state highways, and interstate highways (i.e., interstates). Next, we assessed how each barrier influenced pronghorn space use during the winter as indexed by the area occupied, and daily displacement relative to the density of barriers on an individual's winter range. The semi-permeability of the 5 barriers varied substantially, with the interstate being the most severe barrier to pronghorn movement. Pronghorn were >300 times less likely to cross interstates compared to state highways. Although pronghorn space use was rarely influenced by barriers within individual core winter ranges, pronghorn space use was constrained by barriers on the buffered periphery of individual winter ranges. Despite their different permeability to movement, the density of fences and combined interstates and railroads had similarly negative effects on pronghorn space use. Our results illustrate that the degree to which pronghorn avoid crossing barriers may scale up to affect access to habitat. Additionally, our results indicate that the effects of barriers on habitat access are not proportional to their permeability. Our results add to a growing consensus that effective management of mobile species depends on understanding how different kinds of semi-permeable barriers influence access and use of habitats.     

道路对三江源国家公园黄河源园区藏野驴和藏原羚种群数量及其栖息地的影响

为探究道路对三江源国家公园黄河源园区藏野驴(Equus kiang)和藏原羚(Procapra picticaudata)种群数量及其栖息地的影响,于2020年冷季采用截线取样法在黄河源园区进行实地调查.通过设置4种不同等级的道路情景,使用MaxEnt模型评价藏野驴和藏原羚的生境适宜性,模拟了不同等级道路变量情景下两种...     

Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem

Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists.     

Food overlap between Mongolian gazelles and livestock in Omnogobi,southern Mongolia

Botanical and particle size compositions of the feces of sympatric Mongolian gazelles, sheep/goats, and horses collected in southern Mongolia in autumn 2002 were analyzed. The botanical composition of Mongolian gazelles was similar to that of sheep/goats where dicotyledonous plants (64.6% for Mongolian gazelles, 65.6% for sheep/goats), particularly woody fibers were important (39.5% for Mongolian gazelles, 19.5% for sheep/goats). In contrast, horse feces were exclusively composed of graminoids (93.2%). Consequently, food overlap was great between Mongolian gazelles and sheep/goats (Piankas index: 0.977) but was small between Mongolian gazelles and horses (0.437) and sheep/goats and horses (0.421). Particle size distributions were also similar between Mongolian gazelles and sheep/goats, whereas they were different between horses and Mongolian gazelles and horses and sheep/goats. These results support our expectation based on the Jarman-Bell principle. Although interspecific competition cannot be inferred from a mere food overlap, our analyses suggest that sheep and goats are potential competitors for Mongolian gazelles. Therefore, the increase in the numbers of domestic sheep/goats might pose a risk for Mongolian gazelle populations.     

Road crossing in bank voles and yellow-necked mice

Roads and highways represent one of the most important anthropogenic impacts on natural areas and contribute to habitat fragmentation, because they are linear features that can inhibit animal movement, thereby causing barrier effects subdividing the populations adjacent to the roads. The paper examines to what extent a narrow (2-lane) and a wide (4-lane) highways represent barriers for two small mammal species: bank volesClethrionomys glareolus Schreber, 1780 and yellow-necked miceApodemus flavicollis Melchior, 1834, and whether displaced rodents are able to return across roads of different widths. The study was performed at four sites in the Czech Republic. The capture-mark-recapture method was used to determine crossing rates. At two sites, the animals captured close to the road were transferred to the other side and released, to compare return movements across the roads with the movements made by the non-transferred animals. We found that the narrow highway did not prevent movement of neither of the species, although voles crossed only after they had been transferred. Wide highways, on the other hand, completely prevened crossing of both species. While the narrow highways acted at individuals level, the wide highways affected the population subvision.     

Intact landscape promotes gene flow and low genetic structuring in the threatened Eastern Massasauga Rattlesnake

Genetic structuring of wild populations is dependent on environmental, ecological, and life‐history factors. The specific role environmental context plays in genetic structuring is important to conservation practitioners working with rare species across areas with varying degrees of fragmentation. We investigated fine‐scale genetic patterns of the federally threatened Eastern Massasauga Rattlesnake (Sistrurus catenatus) on a relatively undisturbed island in northern Michigan, USA. This species often persists in habitat islands throughout much of its distribution due to extensive habitat loss and distance‐limited dispersal. We found that the entire island population exhibited weak genetic structuring with spatially segregated variation in effective migration and genetic diversity. The low level of genetic structuring contrasts with previous studies in the southern part of the species’ range at comparable fine scales (~7 km), in which much higher levels of structuring were documented. The island population''s genetic structuring more closely resembles that of populations from Ontario, Canada, that occupy similarly intact habitats. Intrapopulation variation in effective migration and genetic diversity likely corresponds to the presence of large inland lakes acting as barriers and more human activity in the southern portion of the island. The observed genetic structuring in this intact landscape suggests that the Eastern Massasauga is capable of sufficient interpatch movements to reduce overall genetic structuring and colonize new habitats. Landscape mosaics with multiple habitat patches and localized barriers (e.g., large water bodies or roads) will promote gene flow and natural colonization for this declining species.     

黄羊（Procapra gutturosa）在中国分布的变迁及其资源持续利用

历史上黄羊曾广布于中国的北部,目前黄羊只分布在我国内蒙古北部的中蒙边境一带。环境的变迁、人类活动的干扰及盲目捕猎是黄羊分布区缩小的重要原因。建议尽快建立黄羊自然保护区,使黄羊在我国有一安歇、繁衍的良好栖息地,最终使黄羊资源得到科学合理的利用。     

Low habitat overlap at landscape scale between wild camelids and feral donkeys in the Chilean desert

Feral domestic ungulates may compete with the populations of wild herbivores with which they coexist, particularly so in arid regions. The potential competition between wild camelids and feral donkeys at the eastern sector of the Atacama Desert is evaluated in terms of their coincidence or segregation in habitat use and complemented with a comparison of reproductive output (yearling/adult ratio) of vicuña family groups in the proximity vs. distant from donkey observations. Habitat use of wild camelids and donkeys was sampled driving some 1250 km of roads and tracks at the dry and wet seasons. There were 221 vicuñas (Vicugna vicugna) sightings, 77 for donkeys (Equus asinus), 25 for guanacos (Lama guanicoe) and 8 for hybrids between guanacos and domestic llamas (Lama glama), as well as 174 randomly selected control locations. By means of Generalised Discriminant Analysis and Analysis of Variance we show that all ungulates actively select their habitat, with significant differences between use and availability in the area. Donkeys are relatively abundant in comparison with camelids and coincide broadly with both of them across the altitudinal gradient, but they fall between them in local scale habitat selection and do not seem to force their displacement from their preferred habitats. Thus donkeys occur preferentially on slopes with a high cover of tall shrubs, whereas vicuñas use valley bottoms with grass and guanacos the upper slope zones with grass. The potential for competition between donkeys and wild camelids is thus limited and it does not affect the reproductive output of vicuña in this region. Therefore, with the present knowledge we suggest that population control is not currently merited for feral donkeys.     

Effects of winter recreation on northern ungulates with focus on moose (Alces alces) and snowmobiles

Winter recreation can displace ungulates to poor habitats, which may raise their energy expenditure and lower individual survivorship, causing population declines. Winter recreation could be benign, however, if animals habituate. Moreover, recreation creates trails. Traveling on them could reduce energy expenditure, thereby increasing ungulate survivorship and generating population benefits. Balancing recreation use with wildlife stewardship requires identifying when these effects occur. This task would be simpler if guidelines existed to inform assessments. We developed and tested such guidelines using two approaches. First, we synthesized literature describing the effects of winter recreation—motorized and nonmotorized—on northern ungulates. This synthesis enabled formulating six guidelines, while exposing two requiring further attention (ungulate habituation and displacement). Second, we tested these two guidelines and evaluated the others by quantifying the behavioral responses of moose to snowmobiles, in two areas of south-central Alaska, differing by snowmobile predictability. For each location, we modeled moose preferences during the snowmobile period using different combinations of eight variables—static (elevation and slope), biotic (habitat and cover), and anthropogenic (distance to roads, railroads, snowmobile trails, and trail density). We identified the model with the most support and used it to estimate parameter coefficients for pre- and post-recreation periods. Changes in coefficients between periods indicated snowmobile effects on moose. Overall, we produced and evaluated six guidelines describing when winter recreation is potentially detrimental to ungulates as follows: (1) when unpredictable, (2) spanning large areas, (3) long in duration, (4) large spatial footprint, (5) nonmotorized, and (6) when animals are displaced to poor quality habitats.     

Predicting Greater Prairie-Chicken Lek Site Suitability to Inform Conservation Actions

The demands of a growing human population dictates that expansion of energy infrastructure, roads, and other development frequently takes place in native rangelands. Particularly, transmission lines and roads commonly divide rural landscapes and increase fragmentation. This has direct and indirect consequences on native wildlife that can be mitigated through thoughtful planning and proactive approaches to identifying areas of high conservation priority. We used nine years (2003–2011) of Greater Prairie-Chicken (Tympanuchus cupido) lek locations totaling 870 unique leks sites in Kansas and seven geographic information system (GIS) layers describing land cover, topography, and anthropogenic structures to model habitat suitability across the state. The models obtained had low omission rates (<0.18) and high area under the curve scores (AUC >0.81), indicating high model performance and reliability of predicted habitat suitability for Greater Prairie-Chickens. We found that elevation was the most influential in predicting lek locations, contributing three times more predictive power than any other variable. However, models were improved by the addition of land cover and anthropogenic features (transmission lines, roads, and oil and gas structures). Overall, our analysis provides a hierarchal understanding of Greater Prairie-Chicken habitat suitability that is broadly based on geomorphological features followed by land cover suitability. We found that when land features and vegetation cover are suitable for Greater Prairie-Chickens, fragmentation by anthropogenic sources such as roadways and transmission lines are a concern. Therefore, it is our recommendation that future human development in Kansas avoid areas that our models identified as highly suitable for Greater Prairie-Chickens and focus development on land cover types that are of lower conservation concern.     

Midden site selection in Dorcas gazelle: Larger is not always better

Dorcas gazelles are believed to use middens to mark their territories and transmit information. Given the commitment to maintaining a midden, it is believed that middens are not placed randomly. We examined how the habitat (tree height and maximum canopy) and anthropogenic disturbance (camel and human presence) influenced the selection of midden sites by Dorcas gazelles in South Sinai, Egypt. Our results showed that Dorcas gazelles did not place middens at larger trees, while favoring relatively smaller trees and shrubs where the anthropogenic disturbance and perceived hunting risk are less. Our results, in light of the previous findings, suggest that selection of midden sites is species context‐dependent behavior. In areas with less anthropogenic disturbance and hunting, Dorcas gazelles have been shown to select the largest trees of the same species as midden sites. In contract, in our study site with high anthropogenic disturbance and no protection from hunting, gazelles did not utilize the presumably optimum landmarks for midden sites. Our study showed that Dorcas gazelles instead utilized smaller trees and some shrubs that are less conspicuous and presumably less effective as advertisement sites, but safer.     

The danger of having all your eggs in one basket--winter crash of the re-introduced Przewalski's horses in the Mongolian Gobi

Large mammals re-introduced into harsh and unpredictable environments are vulnerable to stochastic effects, particularly in times of global climate change. The Mongolian Gobi is home to several rare large ungulates such as re-introduced Przewalski's horses (Equus ferus przewalskii) and Asiatic wild asses (Equus hemionus), but also to a millennium-old semi-nomadic livestock herding culture.The Gobi is prone to large inter-annual environmental fluctuations, but the winter 2009/2010 was particularly severe. Millions of livestock died and the Przewalski's horse population in the Gobi crashed. We used spatially explicit livestock loss statistics, ranger survey data and GPS telemetry to provide insight into the effect of a catastrophic climate event on the two sympatric wild equid species and the livestock population in light of their different space use strategies.Herders in and around the Great Gobi B Strictly Protected Area lost on average 67% of their livestock. Snow depth varied locally, resulting in livestock losses following an east-west gradient. Herders had few possibilities for evasion, as competition for available winter camps was high. Przewalski's horses used three different winter ranges, two in the east and one in the west. Losses averaged 60%, but differed hugely between east and west. Space use of Przewalski's horses was extremely conservative, as groups did not attempt to venture beyond their known home ranges. Asiatic wild asses seemed to have suffered few losses by shifting their range westwards.The catastrophic winter 2009/2010 provided a textbook example for how vulnerable small and spatially confined populations are in an environment prone to environmental fluctuations and catastrophes. This highlights the need for disaster planning by local herders, multiple re-introduction sites with spatially dispersed populations for re-introduced Przewalski's horses, and a landscape-level approach beyond protected area boundaries to allow for migratory or nomadic movements in Asiatic wild asses.     

Exposure of Mongolian gazelles (Procapra gutturosa) to foot and mouth disease virus

Foot and mouth disease is a highly contagious acute viral disease that affects most ruminant and porcine species. During 2001, 33 serum samples were collected from Mongolian gazelles (Procapra gutturosa) in the Eastern Steppe of Mongolia. Samples were tested for antibodies to seven subtypes of foot-and-mouth-disease virus (FMDV). Antibodies were detected in 67% of the animals, and serologic results indicated exposure to FMDV-O. This virus was present in domestic animal populations in Mongolia from 2000 to 2002, and it is likely that the antibodies to FMDV detected in these gazelles resulted from spillover of virus from domestic animal sources.     

High-speed railways are not barriers to Pyronia tithonus butterfly movements

Linear infrastructures such as railways and roads can be barriers to the movements of individuals and, hence, may have strong impacts on populations. We tested the barrier effect of a high-speed railway for Pyronia tithonus, a butterfly species showing homing behaviour when displaced. We captured, marked and displaced 152?individuals in two different locations. One-third of the butterflies were released at a capture plot, one-third on the other side of the railway (in a similar habitat) and one-third on the same side but 100?m away from the capture plot. We obtained recapture rates of 40 and 23?% per location. Many (31?%) butterflies crossed the railway, showing homing behaviour. Thus, contrary to wide, busy roads, high-speed railways do not seem to be barriers for these butterflies. We suggest that in an intensive agrarian landscape, railway verges can play a substitution habitat role for grassland butterflies.     

Roe deer population structure in a highly fragmented landscape

Northern Belgium (Flanders) is one of the most densely populated and urbanized regions in Europe. Many species are therefore likely to suffer from anthropogenic pressure and habitat destruction and fragmentation. Although many large mammals are recolonizing in parts of Europe, including Belgium, due to adaptation, a relaxation of persecution and habitat restoration, we have little actual data concerning the effects of landscape features on their population structure. We analysed the genetic structure of discrete roe deer (Capreolus capreolus) populations in the Eastern part of Flanders, with special emphasis on the impact of habitat fragmentation and anthropogenic barriers. The sampled populations were clearly genetically differentiated. Genetic structure could be explained by purely distance-based landscape modelling, but a simpler model focusing solely on barrier effects of large transportation infrastructure explained nearly as much genetic variance. In contrast, analyses based on least-cost landscape modelling failed to yield a significant effect. Overall, the results suggest considerable landscape-level effects of transportation infrastructure.     

Roads and bats: a meta‐analysis and review of the evidence on vehicle collisions and barrier effects

相似文献   

Anthropogenic and natural barriers affect genetic connectivity in an Alpine butterfly

Dispersal is a key biological process serving several functions including connectivity among populations. Habitat fragmentation caused by natural or anthropogenic structures may hamper dispersal, thereby disrupting genetic connectivity. Investigating factors affecting dispersal and gene flow is important in the current era of anthropogenic global change, as dispersal comprises a vital part of a species’ resilience to environmental change. Using finescale landscape genomics, we investigated gene flow and genetic structure of the Sooty Copper butterfly (Lycaena tityrus) in the Alpine Ötz valley system in Austria. We found surprisingly high levels of gene flow in L. tityrus across the region. Nevertheless, ravines, forests, and roads had effects on genetic structure, while rivers did not. The latter is surprising as roads and rivers have a similar width and run largely in parallel in our study area, pointing towards a higher impact of anthropogenic compared with natural linear structures. Additionally, we detected eleven loci potentially under thermal selection, including ones related to membranes, metabolism, and immune function. This study demonstrates the usefulness of molecular approaches in obtaining estimates of dispersal and population processes in the wild. Our results suggest that, despite high gene flow in the Alpine valley system investigated, L. tityrus nevertheless seems to be vulnerable to anthropogenically‐driven habitat fragmentation. With anthropogenic rather than natural linear structures affecting gene flow, this may have important consequences for the persistence of species such as the butterfly studied here in altered landscapes.     

Spatial and Temporal Patterns of Frugivorous Hornbill Movements in Central Africa and their Implications for Rain Forest Conservation

Tropical forest conservation and restoration require an understanding of the movements and habitat preferences of important seed dispersers. With forests now being altered at an unprecedented rate, avian frugivores are becoming increasingly vital for forest regeneration. Seed movement, however, is highly dependent on the behavioral characteristics of their dispersers. Here, we examined the movements, habitat preferences, and range sizes of two African frugivores: the Black‐casqued (Ceratogymna atrata) and the White‐thighed (Bycanistes albotibialis) Hornbill, in the lowland rain forests of southern Cameroon. Using satellite transmitters, we tracked eight hornbills for 3 yr to characterize their movements and relate them to environmental landscape features. Hornbill movements differed significantly, with B. albotibialis ranging over larger areas (mean = 20,274 ha) than C. atrata (mean = 5604 ha), and females of both species covering over 15 times the area of males. Evidence suggests that movements are irruptive during particular periods, perhaps driven by low resource availability. In addition, hornbills often returned to the same localities within a year, although movements were not characterized as migratory. Both species displayed significant differences in habitat preference, with B. albotibialis utilizing disturbed habitat more frequently than C. atrata (t = ?22.04, P = 2.2 × 10^?16). Major roads were found to act as barriers for C. atrata, but not for B. albotibialis. The ability of both hornbill species to move large distances suggests hornbills will play a vital role in the maintenance and regeneration of rain forests in Central Africa as forest fragmentation increases and terrestrial vertebrates decline in numbers.     

Male post-breeding movements and stopover habitat selection of an endangered short-distance migrant,the Little Bustard Tetrax tetrax

Migratory decisions, such as the selection of stopover sites, are critical for the success of post-breeding migratory movements and subsequent survival. Recent advances in bio-logging have revealed the stopover strategies of many long-distance migrants, but far less attention has been given to short-distance migrants. We investigated the stopover ecology of an endangered grassland bird, the Little Bustard Tetrax tetrax, a short-distance migrant in Iberia. Using high-resolution spatial GPS/GSM data, 27 male Little Bustards breeding in southern Portugal were tracked between 2009 and 2011. We studied post-breeding movements using Dynamic Brownian Bridge models to identify the main stopover sites, and generalized linear mixed models to examine habitat selection in stopovers. During their post-breeding movements, males were essentially nocturnal migrants, making frequent stopovers while maintaining a relatively fast pace to reach more productive agricultural post-breeding areas. Stopovers occurred in most post-breeding movements (83%) regardless of the total distance covered (average 64.3 km), and most stopovers (84%) lasted less than 24 h. Birds used mostly agricultural non-irrigated and irrigated croplands as stopover sites and avoided other land uses and rugged terrain. There was a negative relationship between stopovers and the proximity to roads, but not to power lines. The high frequency of stopovers during post-breeding movements, despite the short distances travelled, together with the nocturnal migratory behaviour of bustards, may impose additional risks to a bird mainly threatened by collision with power lines in non-breeding areas. We also conclude that even for short-distance migrants, habitat connectivity between breeding and post-breeding areas is likely to be a key conservation concern.