Effects of grazing practices and fossorial rodents on a winter avian community in Chihuahua, Mexico

Chihuahuan Desert grasslands are important wintering grounds for grassland and shrub-adapted birds. Many species belonging to these assemblages are currently exhibiting population declines. One area recognized for its importance to biological diversity, including grassland birds, is the Janos-Nuevo Casas Grandes black-tailed prairie dog (Cynomys ludovicianus) complex in northwestern Chihuahua, Mexico, an area containing 58 colonies with 30,000 ha of prairie dogs. This is one of the largest remaining prairie dog complexes and the only intact complex in the Chihuahuan Desert. In its current condition, a large percentage of this complex is of reduced value to wildlife. Overgrazing on communal (ejido) lands has resulted in areas being comprised of annual grasses and forbs. The density of active prairie dog burrows and banner-tailed kangaroo rat (Dipodomys spectabilis) mounds as well as avian diversity and abundance were lower on ejido lands than an adjacent private ranchland with and without prairie dogs. Few avian species used overgrazed portions of the prairie dog colony. Community similarity among plot types was low due to different management practices and differences on and off colony. To retain, and in many instances restore the biological diversity of this important region it is essential to work with local ejidos on grazing management.     

Gaps in the protected area network for threatened Afrotropical birds

Protected areas established for wildlife conservation (IUCN category I-VI protected areas) or for forest and watershed conservation (forest reserves) across mainland sub-Saharan Africa have high biodiversity values. However, they fail to cover over half of the 106 threatened bird species, and thus leave these vulnerable to extinction. An analysis of Red List bird species that are not represented in existing reserves indicates gaps in the current network of protected areas, namely: Mt. Cameroon-Bamenda highlands (Cameroon), the Angolan scarp (Angola), the Drakensberg Highlands (South Africa), the Highveld (South Africa), the Eastern Arc Mountains (Tanzania), the eastern African coastal forest mosaic (Kenya and Tanzania), the Albertine Rift (Uganda, Rwanda, Burundi, eastern Democratic Republic of Congo and western Tanzania), and the Ethiopian Highlands. The addition of Forest Reserves to the existing protected areas closes some of the reservation gaps for threatened birds in Africa. We suggest that these Forest Reserves should be included within official lists of protected areas, and that National forestry authorities be encouraged to manage these areas. Publication of scientific articles showing the conservation value of Forest Reserves is needed to raise local and international support and funding.     

温度对多异瓢虫成虫捕食功能的影响

【目的】研究温度变化对多异瓢虫[Adonia variegata ( Goeze)]成虫捕食棉蚜能力的影响。【方法】在17、23、29和35℃四个处理温度下,室内测定多异瓢虫成虫在不同棉蚜密度条件下的捕食量。【结果】不同温度下多异瓢虫成虫对棉蚜的捕食功能反应属于Holling-Ⅱ型。随着温度的升高,多异瓢虫成虫对棉蚜的捕食能力逐渐增加。在相同温度条件下多异瓢虫成虫对棉蚜的寻找效应随密度的增加而减小。在35℃条件下,多异瓢虫成虫的a/Th最大,捕食能力为17℃的2倍。【结论】温度对多异瓢虫的捕食量影响显著,在一定温度范围内,随温度升高,多异瓢虫成虫的捕食量明显增加。     

Determinants of bird community composition on patches in the suburbs of Paris, France

The ecological processes responsible for the spatial assemblages of breeding bird communities in urban landscapes are more and more investigated. Indeed, understanding these processes is imperative to plan relevant management policies. We investigated breeding bird communities on 67 patches in the suburbs of Paris, France. We examined the role of patch characteristics and geographic distance between patches in determining similarity between bird assemblages. To do this, we proposed a new SØrensen similarity index based on estimators of change in community composition taking into account the detection probability of species. The patch occupancy by sedentary and migratory species was also estimated to compare their sensitivity to urbanization. Patches close to each other supported more similar bird assemblages, suggesting an effect of the spatial distribution of patches on bird dispersal and a posteriori on local community composition. Accounting for spatial location of patches, bird assemblage similarity was related to the similarity of the surrounding level of urbanization but not to the similarity of patch size or to the similarity of patch vegetation. The mean estimated occupancy rate of sedentary species was higher than that of migratory species in the whole study area. While sedentary species occupied patches surrounded by both moderate and high levels of urbanization, migratory ones primarily occupied patches surrounded by moderate levels of urbanization. Human choices in degrees, styles, and extent of urbanization, including designation and design of patches within an urban matrix, affect the composition of local bird communities.     

Short- and long-term implications of clearcut and two-age silviculture for conservation of breeding forest birds in the central Appalachians, USA

Two-age (deferment or leave tree) harvesting is used increasingly in even-aged forest management, but long-term responses of breeding avifauna to retention of residual canopy trees have not been investigated. Breeding bird surveys completed in 1994-1996 in two-age and clearcut harvests in the central Appalachian Mountains of West Virginia, USA allowed us to document long-term changes in these stands. In 2005 and 2006, we conducted point counts in mature unharvested forest stands and in 19-26 year-old clearcut and two-age harvests from the original study and in younger clearcut and two-age stands (6-10 years old). We found differences in breeding bird metrics among these five treatments and temporal differences in the original stands. Although early-successional species are typically absent from group selection cuts, they were almost as common in young two-age stands as clearcuts, supporting two-age harvests as an alternative to clearcutting. Although older harvests had lower species richness and diversity, they were beginning to provide habitat for some species of late-successional forest songbirds that were absent or uncommon in young harvests. Overall, late-successional forest-interior species were more flexible in their use of different seral stages; several species used both age classes and harvest types in addition to mature forest, which may reflect the lack of edges in our heavily-forested landscape. Consequently, two-age management provides habitat for a diverse group of species as these stands mature and may be an ecologically sustainable alternative to clearcutting in landscapes where brown-headed cowbirds (Molothrus ater) are uncommon.     

Distance to edges, edge contrast and landscape fragmentation: Interactions affecting farmland birds around forest plantations

Afforestation often causes direct habitat losses for farmland birds of conservation concern, but it is uncertain whether negative effects also extend significantly into adjacent open land. Information is thus required on how these species react to wooded edges, and how their responses are affected by edge and landscape characteristics. These issues were examined in Mediterranean arable farmland, using bird counts at 0, 100, 200, 300 and >300 m from oak, pine and eucalyptus edges, embedded in landscapes with variable amounts and spatial configurations of forest plantations. Bird diversity declined away from edges, including that of woodland, farmland and ground-nesting birds. Positive edge responses were also found for overall and woodland bird abundances, and for five of the nine most widespread and abundant species (Galerida larks, stonechat, linnet, goldfinch and corn bunting). Strong negative edge effects were only recorded for steppe birds, with reduced abundances near edges of calandra larks and short-toed larks, but not of little bustards and tawny pipits. Edge contrast affected the magnitude of edge effects, with a tendency for stronger responses to old and tall eucalyptus plantations (hard edges) than to young and short oak plantations (soft edges). There were also species-specific interactions between edge and fragmentation effects, with positive edge responses tending to be strongest in less fragmented landscapes, whereas steppe birds tended to increase faster away from edges and to reach the highest species richness and abundances in large arable patches. Results suggest that forest plantations may increase overall bird diversity and abundance in adjacent farmland, at the expenses of steppe birds of conservation concern. Clustering forest plantations in a few large patches and thus reducing the density of wooded edges at the landscape-scale might reduce such negative impacts.     

The importance of gallery forests in the tropical lowlands of Costa Rica for understorey forest birds

Rivers and streams lined by narrow forest strips are common in the lowland countryside of south-western Costa Rica. We studied the importance of these gallery forests for understorey birds, especially forest species. Using mist-nets, we captured 1110 birds belonging to 90 species between June and September 2007 at 16 sites spread equally over four habitat types: forest interior, forest margin, gallery forest connected to closed forest, and isolated gallery forest. Though isolated gallery forests had the greatest number of expected species in total, they supported the lowest number of forest-specialist species, lower even than connected gallery forests. Granivorous birds showed an increase from forest to isolated gallery forest, all other feeding guilds however showed no change. The studied habitats differed from each other in their faunal composition. Assemblages of three species groups categorised by their habitat preferences (forest specialists, forest generalists, non-forest species) showed nested distribution patterns across the four habitats. There was no significant difference in the proportion of birds with brood patches or of recaptures across the studied habitat types, leading to the assumption that birds not only use gallery forests for movement and foraging but also for reproduction. Though of limited conservation value for most forest understorey birds, at least for a small fraction of forest species gallery forests constitute an important secondary habitat. More significantly, they can form corridors or stepping stones that allow movements within the matrix of human-dominated habitats, and represent an important landscape component benefiting total bird species richness in the Costa Rican countryside.     

宁夏沙湖湿地自然保护区涉禽鸟类群落组成及动态迁徙规律研究

2011年3月至2012年2月,对宁夏沙湖湿地自然保护区的涉禽鸟类资源进行了调查,共记录涉禽鸟类32种,隶属于3目、6科、15属.对涉禽鸟类的居留型组成、区系组成、保护级别及迁徙情况进行了分析.     

转Bt基因棉花对棉田天敌的影响

就转Bt基因棉花对棉田害虫寄生性天敌、捕食性天敌的个体发育和种群的影响进行了综述,并且分析了影响机理。     

滇池湖滨区湿地鸟类栖息地适宜性评价研究

2018年7月至2019年5月,每月对滇池湖滨区28个样点和主城区3个滨水公园在内的共计31个样点进行湿地鸟类丰富度和土地覆被因子的调查。通过计算显著影响湿地鸟类丰富度的土地覆被因子参数的适宜性指数（HSI）单因子指数,采用单因素聚类分析将综合HSI（HSI_t）分类,构建滇池湖滨区湿地鸟类栖息地的HSI模型,以此评价该湖滨区各样点作为湿地鸟类栖息地的适宜性。结果表明：滇池湖滨区的样点中除东大河的HSI_t显著高于其他样点为极高适宜区,其他样点HSI_t聚类均值均小于0.6,划分为高适宜区7个、中适宜区10个、低适宜区10个。而城区滨水公园的3个样点中,除翠湖为低适宜区外,莲花池、篆塘的HSI_t显著低于其他样点,为极低适宜区。