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71.
This study aimed to investigate the impact of contamination by persistent organic pollutants (POPs) on Brazilian wildlife. The concentrations of certain POPs, including dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), in the eggs of the brown booby (Sula leucogaster) were measured. The eggs were collected from breeding colonies located on three archipelagos (Saint Peter and Saint Paul, Abrolhos and Cagarras Islands) in the Atlantic Ocean, which are located at different distances from the Brazilian coast (range 4-1010 km). In addition, possible alterations in eggshell characteristics were evaluated. The average values of POPs found in eggs from the archipelago of Saint Peter and Saint Paul (0.05 μg g−1 of ΣPCBs and 0.01 μg g−1 of ΣDDT) and the archipelago of Abrolhos (0.19 μg g−1 of ΣPCBs and 0.03 μg g−1 of ΣDDT) were low compared to the reference values reported in the literature. In contrast, the concentrations measured in eggs from Cagarras (8.4 μg g−1 of ΣPCBs and 1.8 μg g−1 of ΣDDT) were the highest, and this total PCB level is close to the threshold values considered to be harmful to birds. Our findings indicate that the brown booby colony closest to the Rio de Janeiro coast has recently been exposed to DDT. Despite the high pollution levels found on the Cagarras Islands, no alterations in the eggshell weight or the thickness of the analyzed eggs were detected. Hence, more detailed studies are recommended to determine the actual effects of the selected POPs on the Cagarras breeding colony.  相似文献   
72.
Substantial declines in farmland biodiversity have been reported in Europe for several decades. Agricultural changes have been identified as a main driver of these declines. Although different agrienvironmental schemes have been implemented, their positive effect on biodiversity is relatively unknown. This raises the question as to how to reconcile farming production and biodiversity conservation to operationalize a sustainable and multifunctional agriculture. We devised a bioeconomic model and conducted an analysis based on coviability of farmland biodiversity and agriculture. The coviability approach extended population viability analyses by including bioeconomic risk. Our model coupled stochastic dynamics of both biodiversity and farming land‐uses selected at the microlevel with public policies at the macrolevel on the basis of financial incentives (taxes or subsidies) for land uses. The coviability approach made it possible for us to evaluate bioeconomic risks of these public incentives through the probability of satisfying a mix of biodiversity and economic constraints over time. We calibrated the model and applied it to a community of 34 common birds in metropolitan France at the small agricultural regions scale. We identified different public policies and scenarios with tolerable (0–0%) agroecological risk and modeled their outcomes up to 2050. Budgetary, economic, and ecological (based on Farmland Bird Index) constraints were essential to understanding the set of viable public policies. Our results suggest that some combinations of taxes on cereals and subsidies on grasslands could be relevant to develop a multifunctional agriculture. Moreover, the flexibility and multicriteria viewpoint underlying the coviability approach may help in the implementation of adaptive management. Del Análisis de Viabilidad Poblacional a la Co‐Viabilidad de la Agricultura y la Biodiversidad de las Tierras de Cultivo  相似文献   
73.
闽江口湿地的鸟类研究   总被引:24,自引:1,他引:23  
1998-2000年对福建省闽江口湿地的鸟类资源进行了调查,共记录鸟类86种,隶属11目23科,其中古北界鸟类59种(68.6%),东洋界鸟类27种(31.4%),区系组成呈现南、北鸟类混杂分布,以古北界鸟类为主的特征,留鸟12种,占鸟类总数13.9%;迁徒鸟74种,占86.1%。该湿地鸟类的多样性表现出明显的季节性,迁徒季节鸟类的各类和数量都最多,繁殖季节则最少,该湿地有国家二级保护鸟类9种,中日修鸟保护协定名录中的鸟类49种,并对鸟类资源的保护和管理提出了建议。  相似文献   
74.
鄱阳湖候鸟保护区的自然环境   总被引:2,自引:0,他引:2  
根据较丰富的第一手资料,叙述了鄱阳湖候鸟保护区内的自然环境因素:气候、水文、水质、动植物资源等。调查表明,保护区内冬季气候温和,平均气温在5.0℃以上,平均水温为6.2℃,每年10月至次年3月的气温、水温和水深适宜候鸟越冬;水质较好;水陆动植物和鸟类资源丰富,有许多国家级保护鸟类,如白鹤、小天鹅等。文章最后呼吁,要切实保护好鄱阳湖这块世界A级自然保护区,增划一些禁猎区、广泛开展爱鸟活动,形成依法护鸟,全民爱鸟的社会风气。  相似文献   
75.
黄河三角洲浅海滩涂湿地环境污染对鸟类多样性的影响   总被引:6,自引:0,他引:6  
1996-2001年对黄河三角洲浅海滩涂湿地环境质量。鸟类多样性进行了较为全面的调查监测与研究。评价了环境质量。分析了鸟类种群组成,区系组成,季节居留型及多样性特点,确定了鸟类多样性分布中心,研究了环境污染对鸟类多样性的影响,提出了保护鸟类多样性的对策建议。  相似文献   
76.
Landscape structure and bird's diversity in the rural areas of Taiwan   总被引:2,自引:0,他引:2  
This study tries to discuss the relationship between landscape structure and organisms in the perspective of landscape architecture.The research hypotheses were then proposed as (1) there are relationships between landscape structure indexes and birds‘ diversity in the rural areas of Taiwan;(2)the relationships between landscape structure and birds‘ diversity will be different in different hierarchical levels.In order to increase the bird species,landscape planners could tries to increase the density of water bodies,but decrease the farms and human planted woods.Decrease the density of constructed and human planted grasslands.Increase the area of un-worked acres,natural grasslands,and the area of water bodies and circular the water bodies and natural forest.In order to increase birds‘ diversity,landscape planners could decrease the concentration of paved areas.Concentrate the human planted trees to increase the core areas of woodlands.Increase the area of natural grassland circular.In order to increase the total number of birds in the planning areas,landscape planners could scattered the paved areas and lengthen the constructed areas.Decreases the core region of the constructed areas.Increase the area of un-worked acres and water bodies.Decrease the disturbance of both the interior area of natural and human planted woodlands and try to increase the density of water bodies.The analysis results showed that the small grain size indexes are more suitable for the rural areas of Taiwan to capture the influential factors of bird communities.The high fragmentation of land usages in Taiwan lessens the influences of the regional landscape pattern.  相似文献   
77.
Abstract:  Since 1960, most of the forest surrounding the La Selva Biological Station, an intensively studied tropical research facility in Costa Rica, has been converted to agricultural uses. We used quantitative censuses and analysis of previously published categorical abundances to assess changes in the bird community, and we evaluated potential causes of species-specific changes by assessing their association with habitat, diet, participation in mixed-species flocks, and nest type. Approximately the same percentage of species increased as decreased in abundance from 1960 to 1999 (10–20% of all species, depending on method of assessment). Diet was the single most important trait associated with declining species. At least 50% of the species that declined have insectivorous diets. Use of forest habitat and participation in mixed-species flocks were also significant factors associated with declines, but nest type was unrelated to change in abundance. The species that increased in abundance tended to occur in open habitats and have omnivorous diets. These results reinforce the importance of several population risk factors associated with tropical understory insectivory and mixed-species flocking: patchy spatial distribution, low population density, large home range, and dietary specialization. La Selva's protected area (1611 ha), despite a forested connection on one boundary with a higher elevation national park, is apparently too small to maintain at least one major guild (understory insectivores). This first quantitative assessment of bird community change at La Selva highlights the need to intensify study of the mechanisms and consequences of biological diversity change in tropical forest fragments.  相似文献   
78.
Abstract:  The impacts of potential linear barriers such as roads, highways, and power lines on rainforest fauna are poorly understood. In the central Brazilian Amazon, we compared the frequency of local movements (≤300 m long) of understory birds within intact forest and across a 30- to 40-m-wide road over a 2-year period. Rainforest had regenerated along some road verges, to the extent that a nearly complete canopy was formed in some areas, so we also assessed whether this facilitated bird movement. Movement data were determined from 1212 recaptures of 3681 netted birds at six study sites. The road significantly inhibited total bird movement across roads at five of the six sites. Bird foraging guilds varied in their responses to the road and different ages of regrowth. Movements of frugivorous and edge and gap species were not inhibited at any site, whereas most forest-dependent insectivores (mixed-species flocks, terrestrial species, and army-ant followers) had markedly inhibited road-crossing movements, except at sites with extensive regrowth. Solitary understory species were especially vulnerable, rarely crossing even roads overgrown by tall regrowth. For sensitive species, road-crossing movements were inhibited because individuals tended to avoid both edge-affected habitat near the road and the road clearing itself. Our results suggest that even narrow roads with low traffic volumes can reduce local movements of many insectivorous birds in Amazonia.  相似文献   
79.
Demographic Responses by Birds to Forest Fragmentation   总被引:1,自引:0,他引:1  
Abstract:  Despite intensive recent research on the effects of habitat loss and fragmentation on bird populations, our understanding of underlying demographic causes of population declines is limited. We reviewed avian demography in relation to habitat fragmentation. Then, through a meta-analysis, we compared specific demographic responses by forest birds to habitat fragmentation, providing a general perspective of factors that make some species and populations more vulnerable to fragmentation than others. We obtained data from the scientific literature on dispersal, survival, fecundity, and nesting success of birds. Birds were divided into subgroups on the basis of region, nest site, biogeographical history, and migration strategy. Species most sensitive to fragmentation were ground- or open-nesters nesting in shrubs or trees. Residents were equally sensitive to fragmentation in the Nearctic and Palearctic regions, but Nearctic migrants were more sensitive than Palearctic migrants. Old World species were less sensitive than New World species, which was predicted based on the history of forest fragmentation on these two continents. Pairing success was the variable most associated with fragmentation, suggesting an important role of dispersal. Fledgling number or condition, timing of nesting, and clutch size were not associated with sensitivity to fragmentation, suggesting that negative fragmentation effects on birds do not generally result from diminished food resources with increasing level of fragmentation. Future studies on demographic responses of birds to habitat fragmentation would be more effective if based on a combination of measures that can distinguish among the demographic mechanisms underlying population changes related to habitat fragmentation.  相似文献   
80.
检测了广州市白云山风景区白头鹎(Pycnonotussinensis)、暗绿绣眼鸟(Zosteropsjaponicus)、大山雀(Parusma jor)和白眉(Emberizatristrami)4种鸟的飞羽、胸肌和肝脏中Cd、Cr、Cu、Pb和Zn的残留量。结果表明:除Cd在胸肌中未检出外,其他元素在各组织中均有检出。Cd在鸟的肝脏和飞羽中残留量分别为0.2~5.7和0.0~0.5μg·g-1。在鸟的肝脏、胸肌和羽毛中,Cr残留量分别为未检出~0.3、0.3~0.9和0.6~1.3μg·g-1;Cu残留量分别为15.2~88.4、12.6~32.3和5.4~30.8μg·g-1;Pb残留量分别为0.8~15.0、0.0~1.7和5.4~28.0μg·g-1;Zn残留量分别为58.3~347.0、19.5~104.0和114.0~367.0μg·g-1。羽毛中Cr、Pb和Zn残留量较高,Cu残留量较低;肝脏中Cd和Cu残留量较高,而Cr残留量较低;各元素在胸肌中残留均较低。鸟组织中重金属残留量存在种间差异,但不同元素差异程度不同。暗绿绣眼鸟和白眉组织中Cd、Cr、Cu、Pb残留量种间差异显著,而Zn残留量种间差异不显著。不同重金属元素在鸟组织中的残留分布特性有较大差异。  相似文献   
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