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1.
The Lower Kihansi Hydropower Project in southern Tanzania caused the diversion of the Kihansi River from the Kihansi Gorge in the year 2000. By sampling the understorey avifauna prior to diversion, we examined (i) whether the adjacent Udagaje Gorge was an adequate control for observations in the Kihansi Gorge; (ii) which species of conservation interest occurred; and, (iii) which season best suited annual monitoring. Species composition and capture rates at three and two elevational transects in the Kihansi Gorge and Udagaje Gorge, respectively, confirmed that Udagaje had a comparable avifaunal assemblage to Kihansi. The cold season was most appropriate for population monitoring because >2 times more individuals were captured in the cold than hot season at both gorges, and at least four altitudinal migrants were present in the cold but not hot season. Post-diversion sampling revealed that only the Upper Kihansi transect suffered a significant decrease in number of individuals, a result that was driven largely by a decline in the Little Greenbul, Andropadus virens. This transect is closest to the Kihansi waterfall and associated spray zone which were lost after river diversion. Lack of differences in bird communities at other transects after diversion illustrates that early post-diversion effects on birds are probably concentrated near the base of the main falls. Together with studies of other biota in Kihansi, we propose that long-term monitoring is necessary to understand the factors that regulate changes in species composition of this threatened forest site.  相似文献   
2.
Ornithochory and plant succession in mediterranean abandoned orchards   总被引:1,自引:0,他引:1  
Data on the occurrence of species with fleshy diaspores and on breeding birds were collected in three abandoned orchards, resp. 8, 11 and 24 years after abandonment. Most of the 41 phanerophytes and vines with fleshy diaspores are also found in the borders of the orchards, the more so if the number of years since abandonment increases. Most species have small seeds and red or black coloured diaspores, most of which ripen in autumn. The frequent species show a characteristic distribution pattern in relation to the distance of the fruit trees: high densities near the trunk and uniform decrease with distance. This is explained by the behaviour of frugivorous birds. No correlation was found between distribution patterns and soil conditions. Age structure of colonizing species shows a distribution conforming an inversed J curve in the more recently abandoned orchard. The main conclusions are:
  1. Pioncor trees are attractive for frugivorous birds and may act as nuclei. This supports the facilitation model.
  2. The distribution of diaspores by birds helps to homogenize the species distribution on the regional level but at the site level individual differences in nucleation cause a heterogeneity.
  相似文献   
3.
Aim To analyse the distributional patterns of the Baja California Peninsula's resident avifauna, and to generate a regionalization based on a method that uses a parsimony analysis (parsimony analysis of endemicity, PAE) of point data and modelled potential distributions. Location The Baja California Peninsula, Mexico. Methods A data base was constructed containing records of 113 species of resident terrestrial birds present in the Baja California Peninsula. Records and localities were obtained from the literature and from specimens housed in scientific collections world‐wide. Raw data points and potential distribution maps obtained using the software Genetic Algorithms for Rule‐set Prediction (GARP), were analysed with PAE. Results The data base consisted of 4164 unique records (only one combination of species/locality) belonging to 113 terrestrial resident bird species, in a total of 809 localities. From the point distribution matrix, the analysis generated 500 equally parsimonious trees, from which a strict consensus cladogram with 967 steps was obtained. The cladogram shows a basal polytomy and some geographical correspondence of a few resolved groups obtained in the analysis. These results do not allow the recognition of areas defined by avifaunistic associations. From the potential distribution matrix, the analysis generated 501 equally parsimonious trees, and a strict consensus cladogram of 516 steps was obtained. The cladogram shows a higher resolution because of the number of resolved groups with better geographical correspondence and therefore regions are well‐defined. Main conclusions The correspondence of some groupings of species suggest their validity as areas with biogeographical (historical and/or ecological) meaning. This regionalization in the Baja California avifauna seems to be consistent with previous regionalizations for other groups. Hence, PAE is a useful tool for area categorization if reliable point records and prediction tools are available. Our results suggest that the geographical definition is much better using potential data generated by GARP, particularly when they are contrasted with the results from point data. Thus, this is an excellent alternative for developing biogeographical studies, as well as for improving the use of data from scientific collections and other sources of biodiversity information.  相似文献   
4.
浙江安吉龙山林场及其周围地区的鸟类   总被引:1,自引:0,他引:1  
浙江安吉龙山林场及其周围地区共记录到鸟类11目27科95种,其中留鸟36种,占鸟类总数的38%,延徒鸟59种,占62%。夏候鸟于春季(4月7日)到达,秋季(10月24日)离去,持续停留时间约201天。大部分冬候鸟和旅鸟于秋季(9月12日)出现,春季(5月16日)离去,持续停留时间约247天。柳莺,主要是黄柳莺的情况比较特殊,除6月份外,几乎全年都可看到。人工林内有鸟类84种,条带统计记录到59种。  相似文献   
5.
In their recent comment in this journal, T. M. Blackburn and colleagues called into question the use of standardized partial regression modelling (also called path analysis and structural equation modelling) when null expectations for regression coefficients are not zero. Here, we answer their critique by showing how randomization can be used to illuminate and interpret causal modelling in analyses that have non-zero expectations. Causal modelling is a powerful tool that can yield novel insights in biogeography when properly interpreted.  相似文献   
6.
7.
西双版纳茶林及橡胶林区鸟类调查   总被引:10,自引:1,他引:9  
1983年5—7月,作者对云南省西双版纳的勐海、勐养和勐腊三个地区的茶林和橡胶林区的鸟类区系组成情况进行了调查,其结果若与开发前(郑作新、郑宝赉,1961,1962;A.И.伊万诺夫,1961)的记录对照,在季节时间上有所不同,但该地区的热带雨林和季雨林被开垦种植为茶林、橡胶林及其它经济作物之后,反映出各林区现在的繁殖鸟种类减少很多,鸟类区系组成情况有显著的变化。  相似文献   
8.
Increasing demands for the restoration of nature in cities have led planners to seek an effective form, configuration and maintenance scheme for parks and open spaces in urban areas. This paper aims to introduce two contrasting examples of ways that planners have met the challenge of restoring nature in the city. It takes Tokyo Bay Bird Sanctuary Park (TBBSP), Tokyo, Japan, and Tommy Thompson Park (TTP), Toronto, Canada, as case studies. TBBSP is located on reclaimed land facing Tokyo Bay, and is surrounded by heavily industrialized areas. The absence of green corridors which connect TBBSP to surrounding green patches have turned TBBSP into an isolated oasis for migrating birds. TTP in Toronto is also located on reclaimed land facing Lake Ontario. However, TTP has become to be an indispensable green patch of the open space network of Toronto because it is located at the node of green corridors. The principles of landscape ecology may dictate that TTP, integrated in the green network of the area, is in far better condition than isolated TBBSP. However both case studies are based on the same early post-war parks and open space planning concept, which aimed to clearly separate urban greens from surrounding urban fabrics. To restore nature in cities it is important to understand that alternative models of parks and open space planning can exist. We therefore refer to the authentic urban pattern found in Japanese cities, which historically have not intended to clearly separate each land use types but have sustained a mix of open spaces and urban fabrics. In the context of the global concern to realize ecological cities, restoring a city by integrating greens in the urban fabric should be understood as a way of achieving a city in nature.  相似文献   
9.
Land‐use change may alter both species diversity and species functional diversity patterns. To test the idea that species diversity and functional diversity changes respond in differing ways to land‐use changes, we characterize the form of the change in bird assemblages and species functional traits along an intensifying gradient of land use in the savanna biome in a historically homogeneous vegetation type in Phalaborwa, South Africa. A section of this vegetation type has been untransformed, and the remainder is now mainly characterized by urban and subsistence agricultural areas. Using morphometric, foraging and breeding functional traits of birds, we estimate functional diversity changes. Bird species richness and abundance are generally higher in urban and subsistence agricultural land uses, as well as in the habitat matrix connecting these regions, than in the untransformed area, a pattern mainly driven through species replacement. Functionally unique species, particularly ground nesters of large body size, were, however, less abundant in more utilized land uses. For a previously homogenous vegetation type, declines in the seasonality of energy availability under land‐use change have led to an increase in local avian diversity, promoting the turnover of species, but reduced the abundance of functionally unique species. Although there is no simple relationship between land‐use and diversity change, land‐use change may suit some species, but such change may also involve functional homogenization.  相似文献   
10.
The middle Pleistocene bird fauna from Pinilla del Valle, Spain, comprises 20 taxa, several of which are reported for the first time from middle Pleistocene deposits of Spain. Today, these species inhabit a variety of habitats, including fresh water, woodland, shrubland, and various open environments. The species inhabiting the latter category are the most numerous.  相似文献   
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