Do fences protect birds from human disturbance?

Outdoor recreation and ecotourism are becoming increasingly popular, but such human activities are not entirely benign to birds. One way to manage wildlife habitats is to restrict public access with a fence or some similar barrier, under the assumption that this provides wildlife with a refuge from human activities. We tested this assumption by measuring the responses of 10 species of birds at a site containing a fence with a relatively large number of visitors on only one side. We compared these responses to those at a less-visited, control site. Responses were measured by quantifying flight initiation distance (FID), the distance birds would allow a human to approach before fleeing. Overall, we found birds on the protected side of the fence responded similarly to birds at the low visitation control site, and significantly differently from birds at the high visitation site. Our results suggest that by reducing the number of humans and providing areas of refuge within highly visited habitats, protective barriers allow birds to behave as they would in an undisturbed environment.     

Use of highway undercrossings by wildlife in southern California

Roads, especially large highways, can have significant impacts on wildlife movement and survival. This is especially true for wide-ranging species, such as mammalian carnivores. Some of these impacts may be mitigated if wildlife can find and utilize passageways under highways. To determine if underpasses and drainage culverts beneath highways are used by wildlife as movement corridors, we monitored 15 such passages near Los Angeles, California using remotely triggered cameras and gypsum track stations. We found that passages were used by a variety of species, including carnivores, mule deer, small mammals, and reptiles. Many types of undercrossings were utilized, indicating that passages beneath highways, even when not originally designed for wildlife, can provide important safe avenues for animals to cross roads. For mammals of conservation concern, including native carnivores and deer, passage dimensions, surrounding habitat, and the extent of human activity were assessed to determine if these factors influenced passage use by these species. Our results show that while many native mammals used passages beneath highways, the presence of suitable habitat on either side of the passage was a particularly important factor predicting use. For deer and coyotes, passage dimensions were also important and should be considered with the presence of suitable habitat when wildlife passages are planned or evaluated. To increase the likelihood of utilization and to help prevent animals from crossing road surfaces, we suggest that simple improvements such as habitat restoration near crossing points and animal-proof fencing that serves to funnel wildlife to passages, can facilitate animal movement between fragmented habitats that are bisected by roads.     

Demographic effects of road mortality in black ratsnakes (Elaphe obsoleta)

Roads negatively affect animal populations by presenting barriers to movement and gene flow and by causing mortality. We investigated the impact of a secondary road on a population of black ratsnakes (Elaphe obsoleta) in Ontario, Canada by radio-tracking 105 individuals over 8 years. The road was not a significant barrier to movement and none of the reproductive classes examined (male, non-reproductive female, reproductive female) avoided crossing the road. However, the road was a significant source of mortality. From a total of 115 road crossings by radio-implanted snakes, 3 individuals were killed by cars, resulting in a mortality rate of 0.026 deaths per crossing. We multiplied this mortality rate by the total number of expected road crossings by all individuals in the population in an active season (340) to estimate the number of road kills (9 individuals) each year. This estimate was higher than the actual number of road kills found, but half the number estimated from road kill models. Population viability analysis revealed that our estimate of road mortality was enough to increase the extinction probability for this population from 7.3% to 99% over 500 years. Road mortality of more than 3 adult females per year increased the extinction probability to >90%. Our results strengthen the view that road mortality can have a pronounced negative effect on populations of long-lived species.     

Spatial patterns and factors influencing small vertebrate fauna road-kill aggregations

We examined the spatial patterns and factors influencing small terrestrial vertebrate road-kill aggregations in the Bow River Valley, Alberta, Canada. We surveyed roads varying in traffic volume, configuration and adjacent landscape attributes for road-kills between 1997 and 2000. The spatial pattern of road-kills was described using neighbour K statistics. We investigated the importance of road-kills at three taxonomic levels using logistic regression. Mammal and bird road-kill indices were consistently higher on a low volume parkway than on the high-speed, high volume Trans-Canada highway (TCH). Birds were more vulnerable to collisions than mammals on the TCH. Road-kill aggregations were nonrandomly distributed. Parkway road-kills were aggregated on small scales and characterized by low clustering intensities compared to the TCH. Road-kills were less likely to occur on raised sections of road. Road-kills tended to occur close to vegetative cover and far from wildlife passages or culverts. Our findings reveal how two distinct road types can have different effects in terms of vertebrate mortality and their spatial pattern. We recommend a series of mitigation measures for existing roads or future road planning projects.     

Using Penrose distance to identify potential risk of wildlife–vehicle collisions

Knowledge of the relationship between wildlife and roads is important for management of wildlife–vehicle collisions, which represent a serious threat to many wildlife populations and to human life and property. Effective reduction of these threats requires identification of variables influencing collision locations, and the use of these variables in spatially-explicit predictive models. We used Penrose distance modeling and 61 confirmed bobcat (Lynx rufus) road mortality locations in southern Illinois, USA, to demonstrate a rapid and accurate technique for the spatial mapping of wildlife–vehicle collision risk. We used the Penrose distance statistic to quantify the similarity between the mean multivariate habitat signature at bobcat-collision areas and road sections throughout the study area. Habitat variables assessed included road-related variables (e.g., traffic volume) and land cover characteristics (e.g., mean patch area of the landscape). Bobcat-collision areas were characterized by smaller, less-clustered habitat patches and more, large independent patches of grass cover than were study area roadway sections in general. As expected for a generalist carnivore in highly-suitable habitat, risk mapping indicated that large sections of the roaded landscape had high similarity to bobcat-collision areas. Unlike other modeling techniques used to identify risk of road mortality, our method requires little field data collection and relies on readily available digital spatial data. This technique can be used by wildlife managers and road planners, and may be particularly important in reduction of road mortality for species such as the Iberian lynx (Lynx pardinus), Florida panther (Puma concolor coryi), and Texas ocelot (Leopardis pardalus), which exist in small populations fragmented by development, and are limited by road mortalities.     

The response of an elephant population to conservation area expansion: Phinda Private Game Reserve, South Africa

Continuous human population expansion pressure on conservation ecosystems restricts wildlife areas, and necessitates active management. In areas of changing land-use and increasing human-animal conflict, responses of wildlife to direct human interventions can inform managers and planners. During August 2004, the boundary fences between Phinda Private Game Reserve and two neighbouring reserves were removed. This study examined behavioural responses of the resident elephants. Older, recently introduced bulls moved into the new area during the first month after fence removal, while younger resident bulls and family groups took between five and eight months. Initially family groups only moved into the new area at night and spent minimal time there, while older bulls spent longer periods of time, regardless of time of day. One year after fence removal, most of the elephants had only expanded their home ranges slightly into the new area. One of the findings of this study is that elephants appear to act cautiously in exploring new areas and responded by moving into the area slowly and over a relatively long time period. This cautious behaviour reduced through time as animals became more familiar with the area. The spatial scale of response of the elephants was relatively small, while the temporal scale of response was relatively large.     

Prolonged persistence of fecally excreted ivermectin from reindeer in a sub-arctic environment

In December 2001 and 2002, feces from reindeer calves treated with ivermectin were distributed on plots established on two types of forested reindeer pasture in northern Finland. The ungrazed plots were on an enclosure that had been fenced to prevent reindeer access for the last 6 years. The grazed plots were on an area that had been heavily stocked by reindeer during the last 5 years. After enclosures had been established, reindeer and large wildlife were prevented from entering by a fence. Topsoil samples (feces, vegetation, and soil) were collected monthly during the summers of the following 2 years, over a period of from 25 to 95 weeks after deposition. The samples were analyzed for ivermectin using HPLC. Although ivermectin degradation rapidly took place during the first spring, considerable residual ivermectin could be measured throughout the sampling time, showing that ivermectin in feces on pasture may not be photodegraded as rapidly as previously believed. The results support the need for further environmental evaluation studies on the use of ivermectin to control reindeer parasites.     

土壤生物工程在北京山区公路绿化中的应用

山区公路边坡绿化不仅可以保护边坡,防治水土流失,而且还可以改善公路施工过程中对环境造成的创伤,已经成为公路边坡治理的重要内容。以北京市怀柔区琉璃河岸坡为试验示范区,以旱柳(Salix matsudana)作为主要的绿化植物,采用扦插、埋根、灌丛垫、柳篱挡墙、梢捆等土壤生物工程措施,对沿河公路路基边坡进行治理,并对施工完成5个月后的生长状况、护坡效果等进行观测调查。结果表明:5种土壤生物工程中旱柳的成活率均在90%以上,在试验区具有很好的适应性;在不同的工程类型、水淹与否等条件下,旱柳的生长状况表现出明显的差异,各措施按旱柳生长状况由好到差排序依次为梢捆、灌丛垫、埋根、扦插、柳篱挡墙;水淹1个月的旱柳基径和株高较未水淹的平均值分别小13.2%和21.4%。     

Performance indices to identify attributes of highway crossing structures facilitating movement of large mammals

Studies assessing the efficacy of wildlife crossing structures often lead to spurious results because of their failure to address masking effects of confounding variables. Confounding variables include variation in human activity, density of crossing structures along the highway corridor, and equality of species' perceived access to each crossing structure. We investigated these issues for wide-ranging large carnivores and their prey species in Banff National Park, Alberta, using data obtained from systematic, year-round monitoring of 13 newly constructed crossing structures for wildlife (underpasses and overpasses) for 34 months post-construction. We standardized the first confounding variable by selecting crossing structures remote from areas of human activity. The second confounding variable we standardized by developing probability models of crossing structure usage assuming habitat homogeneity. We standardized the third confounding variable by developing species-specific, performance indices of crossing structures (=observed through passage usage-expected through passage usage). We regressed the species performance indices against 13 crossing structure variables encompassing structural, landscape, and human activity. Our results suggest that in absence of high human activity structural attributes best explained the performance indices for both large predator and prey species, while landscape and human-related factors were of secondary importance. Crossing structures that were high, wide and short in length strongly influenced passage by grizzly bears Ursus arctos, wolves Canis lupus, elk Cervus elaphus, and deer Odocoileus sp. More constricted crossing structures were favoured by black bears Ursus americanus and cougars Puma concolor. Distance to cover was the most important crossing structure landscape attribute for cougars (negative correlation) and was a significant factor determining passage for grizzly bears, elk and deer (all positive correlations). Our findings underscore the importance of: (a) integrating temporal and spatial variability a priori when addressing the efficacy of crossing structures, and; (b) demonstrate that species respond differently to crossing structure features. In light of these results, we suggest that to maximize connectivity across roads for multiple large mammal species, road construction schemes should include a diversity of crossing structures of mixed size classes. Mitigation planning in a multiple-species ecosystem is likely to be a challenging endeavour and long-term research will aid in the decision-making process.     

Present-day hunting and distribution of dugongs in the Wellesley Islands (Queensland): Implications for conservation

Dugongs were traditionally hunted by netting or spearing from a raft in the Wellesley Islands (Queensland). They are now hunted using a harpoon with a detachable head (wap) from a dinghy with an outboard motor. Despite the increased efficiency in hunting techniques, other factors (usually sociological) today mitigate against hunting on a large scale and the estimated number of animals killed each year (40) is about a tenth of the maximum numbers counted on aerial survey (374). The peak period of hunting activity takes advantage of the seasonal movements of dugongs within the island group. However, at all times of the year, a significant proportion of dugongs seen from the air occurred in areas where hunting now rarely takes place. Some hunters also avoid the capture of pregnant females as a conservation measure.The importance of initiating a programme to educate the Wellesley Island Aboriginals to take further responsibilities for their wildlife, including dugongs, is discussed.     

Restoring habitat permeability to roaded landscapes with isometrically-scaled wildlife crossings

Globally, human activities impact from one-third to one-half of the earth’s land surface; a major component of development involves the construction of roads. In the US and Europe, road networks fragment normal animal movement patterns, reduce landscape permeability, and increase wildlife-vehicle collisions, often with serious wildlife population and human health consequences. Critically, the placement of wildlife crossing structures to restore landscape connectivity and reduce the number of wildlife-vehicle collisions has been a hit-or-miss proposition with little ecological underpinning, however recent important developments in allometric scaling laws can be used to guide their placement. In this paper, we used cluster analysis to develop domains of scale for mammalian species groups having similar vagility and developed metrics that reflect realistic species movement dynamics. We identified six home range area domains; three quarters of 102 species clustered in the three smallest domains. We used HR^0.5 to represent a daily movement metric; when individual species movements were plotted against road mile markers, 71.2% of 72 species found in North America were included at distances of ?1 mi. The placement of wildlife crossings based on the HR^0.5 metric, along with appropriate auxiliary mitigation, will re-establish landscape permeability by facilitating wildlife movement across the roaded landscape and significantly improve road safety by reducing wildlife vehicle collisions.     

Do fences create an edge-effect on the movement patterns of a highly mobile mega-herbivore?

Physical barriers, such as rivers and roads, constrain the movement of animals, usually by preventing access to adjacent habitats and impeding dispersal. Fences are artificial barriers that are commonly used as a conservation tool to intentionally restrict movements of animals to within protected reserves. However, the potential edge-effect of fences on the behaviour of animals within reserves is poorly understood. We examined the effect of fences on the movement patterns of African elephant (Loxodonta africana), an ecosystem modifier, in Pilanesberg National Park, South Africa. We used linear and non-linear models to determine the relationship between minimum distance from fence and seasonal daily net displacement of six GPS-collared female elephant. Elephant movement patterns were best explained by a piecewise regression that showed a strong negative relationship between minimum distance from fence and daily net displacement up to a “breakpoint” distance of 2551 m in the dry season and 3829 m in the wet season. The effect of the fence dissipated beyond this distance in both seasons. The increased tortuosity in movement patterns of elephant in the central area of the reserve suggested that they used this area more intensively for foraging compared to the peripheral area, as confirmed by differences in habitat selection. This occurs despite there being no difference in habitat composition between these areas. The decreased use of areas near the fence and more intensive foraging in the central areas constitute an important edge-effect of fences. Since elephant are ecosystem engineers, such edge-effects could potentially cascade throughout the reserve, adversely altering ecologically processes, particularly in reserves with a high edge-to-area ratio.     

草原煤矿排土场2种常用生物工程措施植被恢复效果评价

以锡林郭勒草原乌兰图嘎煤矿排土场为主要研究对象,通过对生物笆与沙障2种不同治理措施下的土壤状况（温度、湿度、有机质、pH值）和植被状况（种类组成、密度、盖度）的测定与分析,对其植被恢复效果进行了评价。初步分析表明,生物笆区的表土温度比沙障区低2～5℃,生物笆具有遮阴性;生物笆区的表土湿度比沙障区增加0.60%～1%,生物笆具有增湿性。在措施实施5 a后,生物笆区的表土有机质比沙障区增加了2～5.80 g/kg。在整个植物群落中,多年生草本所占植物种类总数的比例,生物笆区比沙障区多13.84%;生物笆区以多年生植物的重要值较大并占有绝对优势,沙障区以一年生植物占优势;生物笆区的植被平均密度比沙障区多2.60株/m²,盖度大18.50%。在锡林郭勒草原矿区目前常用的生物笆（单网格20 cm×20 cm）治理措施比沙障（行距30 cm,株距10 cm）更有利于植被恢复。     

基于无人机遥感影像监测土地整治项目道路沟渠利用情况

为客观监测和有效评价土地整治项目基础设施建后利用情况,初步探讨利用无人机航拍影像结合智能算法识别设施利用状态的可能性,该文选取典型项目,利用多旋翼无人机航拍获取高分辨率影像,提取田间道路和骨干沟渠影像网格切片,通过BoW模型构建典型地物样本特征库基于样本纹理特征进行分类,利用支持向量机模型对研究区骨干线状基础设施利用状况进行识别,并依据目视解译和实地勘察对识别结果进行了精度验证。结果显示无人机遥感方法可以初步识别研究区基础设施建后利用情况;研究区田间道路病害和骨干沟渠淤塞情况识别总体分类精度达到80%和70%;田间道路分类误差主要来自通行不畅与路面裂缝,骨干沟渠分类误差主要来自轻度淤塞;提高影像精度情况下,田间道路利用状况识别精度有所提升但不显著,骨干沟渠通畅状况识别精度无明显变化,模型对宽度2 m以下沟渠识别结果精度较差。研究表明,基于无人机遥感对土地整治项目基础设施利用情况进行自动分类识别具有可行性且效率较高,而监测精度有待于后期进一步提升。     

Life in the suburbs: Behavior and survival of a freshwater turtle in response to drought and urbanization

Urbanization fundamentally alters the abiotic and biotic components of landscapes, presenting wildlife with serious challenges to which they must respond in order to avoid excess mortality from urban dangers. In this study, we used radio-telemetry to examine the behavior and survivorship of an Australian freshwater turtle, Chelodina longicollis, in a suburban environment compared to a control group on an adjacent nature reserve. We expected turtles in the suburbs to be less mobile, but the suburban environment did not inhibit the ability of turtles to traverse large areas and make frequent movements among several different wetlands. In fact, suburban turtles were more vagile, moving distances twice as far as those on the nature reserves. Turtles on the nature reserve responded to dropping water levels during drought by estivating for several months in sheltered woodland micro-habitats. Suburban turtles did not estivate terrestrially, in part because their water bodies experienced dampened water level fluctuations and retained water during drought, though the relative unavailability of suitable estivation sites and perceived threats could also account for their avoidance of extended forays into the terrestrial environment. Annual survival rate was 95.3% in the reserves compared to 87.6% in the suburbs, but this 7.7% decrease in survival from road mortality was not significant in our survivorship models. The continued ability of suburban turtles to remain vagile without suffering from high mortality rates is likely a product of the availability of vegetated drainage lines and under-road “box” culverts that allow turtles to travel safely throughout the suburban landscape.     

基于风洞模拟试验的典型机械防沙工程防护效益对比

为探究3种典型机械防沙工程措施实施后所体现的防护效益，通过风洞模拟试验，以敦煌黑山嘴地区的典型机械防沙工程为参考，对草方格与尼龙网格状沙障及阻沙栅栏的防风、固阻沙效益进行系统的对比分析。结果表明：草方格与尼龙网格状沙障的布设均能有效降低风速，当指示风速为20 m/s时，1.5 cm高度的风速降低率分别达到82.5%与80.9%,同时极大地增加流沙地表粗糙度，显著影响当地的风速变化；此外，两者在不同高度对风速削弱能力差异明显；草方格与尼龙网格状沙障也深刻影响当地风沙流结构，其中草方格沙障的固沙能力主要体现在近地表；阻沙栅栏前后平均输沙率降低44.2%,同时对当地流场结构影响深刻。综合分析可知，草方格与尼龙网格状沙障防风、固沙效益良好，阻沙栅栏阻沙效益显著。研究结果可为当地机械防沙工程建设提供指导，同时对其他地区防沙工程布设予以借鉴。     

黄土丘陵区路面种草对水土保持的影响及成本效益分析

土质道路广泛分布于中国的农村、公园和自然保护区，由于设计标准低，常常引发严重的水土流失，是农村道路损坏的主要原因。1997～2001年，以黄土高原丘陵沟壑区陕西省延安市下砭沟小流域农业作业道路为背景，以防止和减轻路面汇流引发的水土流失对道路的破坏为目的，采用小区径流监测和施工统计的方法，在路面进行了为期5年的种草试验。研究结果显示，路面种草后径流量减少76.38%，土壤侵蚀量减少69.47%，建设成本比石子路减少71.65%，维护费用比对照减少60.97%，是一种经济可行的技术途径。对各地土质路面土壤侵蚀治理和道路维护具有广泛参考价值。     

The efficacy of feral cat, fox and rabbit exclusion fence designs for threatened species protection

Pen and field trials were used to test the effectiveness and cost-efficiency of wire netting and electric fence designs as barriers to feral cats, foxes and rabbits in northern South Australia. A 180 cm high wire netting fence with foot apron and a curved ‘floppy’ overhang effectively contained most rabbits, feral cats and foxes during pen trials and proved effective with intensively monitored paddock-scale exclosures. A reduced height fence of 115 cm did not reduce effectiveness of the fence during fence trials but paddock-scale trials are yet to be completed. Conventional 40 mm diameter hexagonal “rabbit netting” was not an effective barrier against young independent rabbits and it is recommended that 30 mm hexagonal netting should be used. A 60 cm wide external netting overhang, curved in an arc and supported by lengths of heavy gauge wire, effectively precluded more feral cats and foxes than a 30 cm wide overhang angled upwards. The 30 cm foot apron was augmented in erosion-prone dunes and watercourses by the addition of wider netting or rubber matting to prevent incursions. Posts, and particularly corners, were targeted by feral cats and foxes and the efficacy of the fence was improved by using steel, rather than timber posts. Electric wires offset from the netting at heights of 120 and 150 cm provided a shock to animals exploring the base of the overhang and further improved the fence efficacy. PVC conduit rollers on the top wire were not effective.Material costs ranged from AUD $8814 per km for the 115 cm high fence to AUD $12,432 per km for the 180 cm high fence with two electric wires. The non-standard 30 mm hexagonal netting accounted for 57% of the material costs of the low netting fence. Increased demand for this netting may reduce the expense of rabbit exclusion. Expenses could also be reduced where existing stock fences are modified by the addition of netting.     

河北省坝上风电场建设区水土流失特点与植被恢复途径

以河北省坝上风电场建设区为研究对象,探讨风电场建设区水土流失特点、分区、防治重点及植被恢复措施。结果如下：风电场建设区水土流失特点为风电场工程的特殊性与坝上水土流失特征的相互耦合的表现;风电场建设区水土流失特点表现为点状与线状侵蚀并存,风蚀与水蚀共存,植被破坏点多面广、植被恢复难度大,土石方量较小、弃渣相对较少,水土流失重点在施工建设期等;风电场建设区的水土流失主要来自升压站、风机区、施工生产生活区、道路区、集电线路区和弃渣场等6个区域,不同区域的水土流失特点和防治重点各有侧重;坝上风电场建设区的植被恢复可采取封育恢复自然植被,清理表土集中覆盖、利用土壤种子库恢复植被及人工植被建设3类途径。     

Wildlife as a source of protein in Africa South of the Sahara

The protein deficiency problems of Africa south of the Sahara are growing in seriousness with the increasing human population. Domestic livestock, on which very high hopes have hitherto been set, have continued to fail to meet existing demands, let alone to keep in step with increasing human population growth. There has been increasing exploitation of the meat of wild animals, whose management is ignored. This source of meat supplements domestic sources. The exploitation of wild animals, coupled with increasing pressure on the habitat of the animals, is exterminating most of the wild animal species involved. Advice that existing scientific knowledge on the management of wild animals must be applied to ensure their rational exploitation on a sustained-yield basis, has continued to be ignored— with the excuse that facts and figures are not available to justify investment in wildlife conservation that will ensure a sustained yield of the badly-needed animal protein. Every attempt must be made by those entrusted with the responsibility of wildlife conservation to bring together scattered information on the subject and, at the same time, begin to collect, systematically, statistical information on the utilization of wild animal meat as food—also to ensure that wildlife conservation receives the priority it deserves in the management of natural resources in Africa south of the Sahara. This is inevitable if wildlife conservation is to be able to meet the economic justification without which one nation after another will continue to give very low priority to wildlife conservation—to the detriment of the region—where malnutrition and poaching are serious realities as are also overgrazing, expansion of desert land, and human population explosion. Despite the fact that general experience indicates the need for concerted action, it appears that, in the absence of readily-available statistical data, which are supposed to be required by policy-makers and financiers, these people are not prepared to face their duty effectively to finance proper wildlife conservation and rational utilization of wildlife resources of Africa south of the Sahara.