Death from anthropogenic causes is partially compensatory in recovering wolf populations

There is substantial interest in how mortality rates affect animal populations, but mechanisms explaining when and under what circumstances particular causes of death incur demographic responses are far from clear. In theory, small or expanding populations should experience additive mortality from anthropogenic causes of death, but whether such effects are homogenous across a population or expressed only in certain high-risk individuals is open for debate. We used competing risks models to analyze mortality patterns among radio-collared wolves (Canis lupus, n = 711) from three populations in northwestern United States (1982-2004), and evaluated the degree to which anthropogenic mortality was additive vs. compensatory to natural demographic processes. Almost 80% (n = 320) of wolves dying of known fates were killed by anthropogenic causes (legal control, illegal killing, harvest in Canada, vehicle collision), and additive effects of anthropogenic mortality were most pronounced in northwestern Montana where wolf exposure to humans and livestock was high compared to either the Greater Yellowstone Area or central Idaho, where anthropogenic risk was lower. In contrast, risk from natural hazards was lower in northwestern Montana than in the other areas, implying some degree of compensatory mortality from anthropogenic risk. Animals recruited to the study following human-wolf conflict had markedly higher anthropogenic risk than those recruited for standard monitoring purposes, and juvenile wolves as well as dispersers, succumbed to higher anthropogenic risk. Multivariate models revealed that increasing wolf population density promoted higher anthropogenic risk and reduced natural risk, indicating that partially-compensatory effects of anthropogenic mortality actually became increasingly additive with population density. The observed compensatory mortality and hazard heterogeneity in our study implies that demographic responses to mortality risk may be complex and more subtle than previously thought; the density-dependent effect of anthropogenic mortality portends a stabilizing influence of humans on recovering wolf populations. We conclude that future assessment of the role of anthropogenic mortality should include individual-based hazard estimation as a complement to traditional population-level approaches.     

Assessing the effects of a highway on a threatened species using Before–During–After and Before–During–After-Control–Impact designs

Due to the growing awareness of potential impacts of roads, managers demand well-designed studies about the implications of linear infrastructures on ecosystems. We illustrate the application of Before–During–After and Before–During–After-Control–Impact designs (BDA and BDACI) to assess effects of highway construction and operation using a population of great bustards (Otis tarda) as a model. Based on a time series of demographic and distribution data (1997–2009), we developed generalized additive models and classification trees to test the effect of road distance on bustard distribution, identify road-effect distances and explore the seasonality of these effects. Two control zones were selected to test the changes between construction phases on productivity, and population trends using TRIM models. From the start of the road construction, great bustards tended to avoid close proximity to the highway (ca. 560–750 m threshold distance). The exclusion band was narrower during the breeding season. In addition, family groups were less tolerant to highway operation disturbances, as shown by their higher distance effect (ca. 1300 m). Population trends did not differ between impact and control zones during the construction. However, once the highway was in operation, bustard numbers declined gradually up to 50% in the impact zone, remained stable in the closest control zone, and increased in the zone located at the greatest distance from the highway. The effects on density of family groups were less evident. Our approach provides information relevant to great bustard conservation and suggests methods for obtaining information of interest to road managers, that could be applied to linear infrastructures with others species.     

Movements and activities of white-lipped peccaries in Corcovado National Park, Costa Rica

The conservation of remnant populations of white-lipped peccaries in Central America depends on adequate documentation of their habitat needs and behavior. Thus, we monitored the activity patterns, local distributions, and home ranges of 36 (25F:11M) radio-marked white-lipped peccaries, all members of a single “super” herd, in part of Corcovado National Park, their largest stronghold in Costa Rica, during 1996-1998. Peccaries were diurnal all year with a period of reduced activity during the middle of the day. They were found more often than expected (vs. random use) in primary forest during February to May, in secondary and coastal forest during June to September, and in herbaceous swamp during October to January, corresponding to relative fruit abundance. Overall, the peccary herd ranged over an area of <40 km², but use of the area shifted seasonally and movements were reduced when fruit was most abundant. Our data agree with the suggestion that peccary density may be higher where the interspersion or close proximity and mix of seasonally important habitats is high, and thus where peccaries do not have to travel as far for food. Habitat interspersion is therefore a significant conservation concern and should be addressed to make certain that peccary populations are not limited.     

Can an introduced predator trigger an evolutionary trap in a colonial seabird?

Animals use environmental cues, social information and behavioural decision-making rules moulded by natural selection to decide where to breed. We assessed whether the presence of an alien nest predator, the Black Rat (Rattus rattus) is used by a colonial seabird, the Cory’s shearwater (Calonectris diomedea), as an environmental cue in the selection of breeding sites. We compared potential habitat preference using quality of breeders and nest fidelity as response to nest predation between two sub-colonies with different habitat characteristics, breeding success and predation pressure. Quality of individuals was better in the predated habitat and birds did not perceive the presence of predators signalling differences in predation risk and in turn of breeding success. This failure of perception could be at two levels: in the selection of habitat for first breeding and in the breeding dispersal following a reproductive failure. Preference for the sub-colony with higher predation risk suggests the presence of an evolutionary trap. In fact, the introduction of alien predators probably transformed the behaviour of shearwaters in a maladaptive response due to a mismatch between the new environmental factors and their behavioural and evolutionary algorithms. This can be a common pattern in other species with little behavioural plasticity, evolved in stable environments free of predators.     

人为干扰对泰山景观格局时空变化的影响

以TM影像和野外调查为数据源,3S技术为研究手段,对比分析了泰山风景区1986～2001年间不同人为干扰程度区域的景观结构、景观异质性动态变化特征以及景观多样性高程的分异。结果表明,泰山南部人为干扰斑块动态变化高于北部,南部景观结构变化明显,北部轻微。景观多样性动态变化主要是在北部海拔900m以上和南部900m以下区域,揭示了人为活动是斑块分割的主因,景观格局的动态变化取决于人为干扰的程度。研究结果从景观生态学角度为泰山合理调整自然和人为影响,构建理想的景观格局和生态环境奠定了基础。     

白鹿原人工果树林地土壤和农耕地土壤微形态对比研究

选择白鹿原人工果树林地土壤和耕地土壤为研究对象,用偏光显微镜和Qwin软件对土壤微形态进行了观察和定量分析。结果表明:两种土壤和土壤粗颗粒的矿物组合基本一致,主要由石英和长石组成,但颗粒的形态和粒径有一定差别;林地土壤中主要是孔道和填充孔隙,孔隙壁较光滑,剖面中微形态连续变化,而耕地土壤的孔隙形态复杂,孔隙壁相对较粗糙,从上向下微结构明显变化,其中20 cm和35 cm是两个重要转折点;大量隐晶方解石反映土壤环境频繁变化,大量针状方解石出现在犁底层中下部并指示一种短期稳定的土壤环境,大量细晶方解石反映长期稳定的土壤环境。     

Use of an avoidance test for the assessment of microbial degradation of PAHs

An avoidance test using the soil springtail Folsomia candida was used to assess changes in contamination levels at low doses of PAHs following incubation with indigenous microflora. A soil from a former coke site was diluted to 1% in an unpolluted soil from the same site, which was used as a control, then both substrates were remoistened to 80% field capacity. The diluted soil was previously shown to be strongly repellent to F. candida, although not toxic. After 2-month incubation at 20 °C, the mixture lost its repellence capacity and became attractive to the test animal, while the global 16 PAHs content had decreased to a great extent (50%). PAH disappearance was linked to the occurrence of indigenous microbiota able to degrade hydrocarbons.     

Collembola in ecotoxicology—Any news or just boring routine?

Despite the uncontested significance of soils for human nutrition and drinking water quality, the majority of ecotoxicological testing is confined to aquatic test systems. Among the standardised tests for soils, the reproduction test with the springtail Folsomia candida is among the most widely used ones. First steps towards its standardisation were undertaken in the late 1980s. Here we review major advances that have been made since then, with respect to mechanistic, pragmatic and ecological aspects. Specifically we address the ecological relevance of any modifications of the standardised tests. We introduce a miniaturised version of the reproduction test which allows reducing the amount of soil per test unit to one third and the number of synchronised individuals to 40% as compared to the standard test. In addition, we developed an assay using Collembola eggs instead of synchronised adults. First results of a three-species test indicate that the presence of other species may affect choice behaviour. We point out a potential biased view of existing ecotoxicological data with Collembola due to the fact that most results refer to metal contamination. Finally, recommendations for future research are given, with special reference to avoidance and microcosm tests involving Collembola.     

Discrimination of lithogenic and anthropogenic influences on topsoil magnetic susceptibility in Central Europe

The study was performed on the area of the three countries involved in the MAGPROX project (Poland, Czech Rep., Germany). In the first stage the basic map of magnetic susceptibility based on the field topsoil measurement was compiled with an average grid density of 10 km. In the second stage of the study, vertical distribution of magnetic susceptibility of ca. 600 topsoil cores (0.3 m long), collected over central Europe, was examined with respect to the anthropogenic or lithogenic influence on magnetic susceptibility of the soil surface, with the focus being on the interpretation of the areas showing high surface susceptibility values. The maximum values were mostly observed in depths of 3–4 cm. In general seven different types of susceptibility profiles from forest areas and one typical for urban soil are presented. They are a result of a combination of natural (litho- and pedogenic) and anthropogenic contributions. Our results prove that soil profiles, dominated by anthropogenic influence due to atmospherically deposited dust, are characterized by magnetically enhanced humuous layer, corresponding to layer with the highest concentration of heavy metals. Moreover, forest soils show in these cases higher magnetic susceptibility than soils in open areas (grassland, meadows or arable soils).     

Effects of a power line on migration and range use of wild reindeer

Linear infrastructures such as roads, pipelines and power lines can hinder Rangifer migration and reduce the total amount of area available for foraging. We studied the barrier and aversion effect of a 66 kV power line transecting the range of wild reindeer in North Ottadalen, south central Norway using aerial surveys of reindeer distribution (direct measurement of reindeer use) and lichen measurements (indirect measurement of reindeer use) at varying distances from both sides of the power line. We present a clear definition of the expected barrier and aversion effects, and present specific hypotheses and predictions based on these two terms that are often used unclearly in the literature. The aerial surveys and ground observations showed that reindeer crossed underneath and grazed under and on both sides of the power line during 14 out of the 22 years (63.6%) surveys were conducted over the last 31 years. This behaviour was confirmed by the lichen measurements, indicating a higher use of lichen pastures along ridges close to and under the power line compared to those at increasing distances and up to 3 km from both sides of the power line. This winter grazing pattern probably reflects the topographical channeling of reindeer to the ridges along an 8 km wide topographical corridor encompassing the power line and cannot be attributed to the power line itself. We found that direct measurement data (visual observations such as ours or GPS/telemetry tracking) provide less ambiguous information for testing barrier and aversion effects than indirect measurement data (pasture/lichen measurements) that are likely influenced by numerous uncontrollable environmental variables independent of reindeer grazing. Our results contrast with recent studies indicating strong barrier and aversion effects of similar power lines for Rangifer migration and grazing behaviour in alpine terrain.     

Selecting terrestrial arthropods as indicators of small-scale disturbance: A first approach in the Brazilian Atlantic Forest

The growing pressure placed by human development on natural resources creates a need for quick and precise answers about the state of conservation of different areas. Thus, identifying and making use of ecological indicators becomes an essential task in the conservation of tropical systems. Here we assess the effects of small-scale disturbance on terrestrial arthropods and select groups that could be used as ecological indicators in the Brazilian Atlantic Forest. Arthropods were sampled within a continuous forest in the Serra do Mar State Park, southeastern Brazil, both in disturbed and undisturbed areas of the reserve. The abundance of exotic species was higher in the disturbed site, and this pattern seems to be an adequate indicator of anthropogenic disturbance. Species richness of Araneae, Carabidae, Scarabaeidae, Staphylinidae, and epigaeic Coleoptera (pooled) was higher in the undisturbed site, while that of fruit-feeding butterflies was higher in the disturbed site. Species richness was not significantly correlated between any pair of taxa. In contrast, species composition was significantly correlated among most groups, and clearly discriminates the disturbed from the undisturbed site. Moreover, fruit-feeding butterflies and epigaeic Coleoptera composition discriminated disturbed and undisturbed sites even when species were grouped into higher taxonomic levels, which may be a way of overcoming the difficulty of identifying arthropod species from poorly studied, species-rich ecosystems. Potential applications for these indicators include the choice and evaluation of sites for the establishment of natural reserves, elaboration of management plans, and the assessment of ecological impacts due to human activities, either for the purposes of licensing or legal compensation.     

The effects of trampling on Hawaiian corals along a gradient of human use

Coral transplantation was used to evaluate the response of corals to trampling by determining growth and mortality at sites that ranged along a gradient of human use. Human use was measured with observational sampling. A clear progression of coral survivorship along the gradient was evident. Survivorship dropped from 70% at the low impact site to 55% at the medium impact site. Total loss (0% survivorship) was reported from the high impact site after only 8 months, equivalent to less than 200,000 total visitors or 63 people in the water per hour. Where transplanted corals survived, there was no difference in growth, presumably due to the control of activities of people in the water at those sites.