崇明东滩春季鸟类群落特征

2003年春季对崇明东滩潮间带不同生境的鸟类群落进行了调查,共记录到鸟类64种,隶属7目15科。崇明东滩潮间带春季鸟类平均密度为14.60只/hm2,鸟类多样性指数2.08、均匀度指数0.49、优势度指数0.22。芦苇带、海三棱草带和盐渍藻类带是东滩潮间带典型的生境,各生境的鸟类种类、密度和多样性差异较大。其中芦苇带25种,平均密度2.56只/hm2;海三棱草带有48种,平均密度15.38只/hm2;盐渍藻类带36种,平均密度21.04只/hm2。3种生境中盐渍藻类带鸟类的生物多样性最高,海三棱草带最低。研究表明,滩涂围垦、人类活动干扰、互花米草的入侵是影响鸟类在东滩栖息的主要因素。     

武汉桂子山地区冬季鸟类群落结构及多样性研究

2005年11月～2006年3月,对武汉桂子山地区冬季鸟类群落进行了调查,共记录鸟类44种,隶属10目22科。有国家Ⅱ级保护鸟类2种,湖北省重点保护鸟类16种;留鸟32种,冬候鸟11种,旅鸟1种,留鸟构成了冬季鸟类的主体;该地区冬季鸟类密度为4．30只／hm^2,物种多样性指数为2．6477,均匀性指数为0．6997。居民点、乔灌林、绿地和水域生境中,乔灌林鸟类多样性最高,数量最多。     

盐城自然保护区新洋港河口不同生境冬季鸟类群落组成及其梯度变化

沿海湿地是鸟类重要的栖息地,人类活动导致的湿地生境变化对鸟类群落造成了一定的影响。在盐城自然保护区新洋港河口内,人类活动大体上导致了由陆向海方向,形成芦苇沼泽、农田、鱼塘和滩涂4种不同干扰程度的生境。分别在不同生境中设置3条长3 km的样线,对越冬鸟类的种类、数量进行了调查,运用多响应置换过程测试、指示种分析、双向聚类分析和除趋势对应分析等统计方法,研究了不同生境中冬季鸟类的指示物种、群落结构及梯度变化,结果表明:1)4种生境共记录鸟类67种,其中鱼塘生境的鸟类种类最多,为37种;滩涂生境的D'多样性指数在各生境不同时段中为最高,芦苇沼泽生境的H'多样性指数在各生境不同时段中为最高。与其余生境比较,芦苇沼泽、滩涂的均匀度也更高。生境间的差异性与鸟类群落的组成有关。2)MRPP分析表明,芦苇沼泽、农田生境的鸟类组成差异不显著(P0.05);其余组合各生境间的鸟类组成具有显著差异。灰鹤等9种鸟类可分别作为4种不同生境的指示种。3)双向聚类分析法把12种观测条件分为4大类,与生境划分非常吻合。在剩余信息40%水平上,鸟类可聚为7类。利用12种观测条件作为变量进行DCA排序的结果表明,鸟类类群在轴1上可以分为3个集群,分别为适应开阔水域环境的鸟类、依赖水生植被环境的鸟类和依赖陆地植被环境的鸟类。根据结果分析,生境异质性、干扰程度及潮水涨落等与鸟类多样性组成有密切关系;不同生境具有明显的指示种;鸟类群落结构为适应生境变化而出现一定的梯度变化。应加强芦苇沼泽的保护,在开垦农田、鱼塘和在光滩引入互花米草时应考虑到人类活动对鸟类多样性的影响。     

珠海淇澳岛冬季的鸟类群落

在淇澳岛红树林湿地设置7条样带,分别于2005-2007年每年1月对该区冬季鸟类群落特征进行研究.共记录到鸟类63种,隶属12目23科,雀形目种类最丰富;其中留鸟、冬候鸟、夏候鸟分别占66.7%、31.7%和1.6%,水禽和陆禽分别占28.6%和71.4%.鸟类群落总体α多样性指数(H)为3.171,均匀度(J)为0.765;各个样带的H值为0.602～2.853,J值为0.336～0.919,其中滩涂与红树林生境的鸟类群落多样性与均匀度在7种生境中最低.β多样性指数分析表明,滩涂、红树林鱼塘湿地和村落之间的鸟类群落差异较大.根据等级聚类分析的结果,淇澳岛冬季鸟类群落可划分为滩涂水禽、红树林鱼塘湿地鸟类、农田森林鸟类3个群落.     

西天目山低山地区人工与自然生境夏季鸟类群落比较

为了研究西天目山低山地区人类活动对鸟类群落的影响,于2007年7月对该地区两种自然生境(常绿乔木林和灌丛)与两种人工生境(苗圃和公园)中鸟类的种类、数量及鸟类群落的相似性进行比较.结果表明,常绿乔木林与灌丛中的鸟类物种数最多,常绿乔木林中的鸟类密度显著高于灌丛中的鸟类密度.苗圃和公园中鸟类物种数及密度都显著低于常绿乔木林和灌丛.两种人工生境中鸟类群落相似性最高,广性分布物种是这两种生境中鸟类群落的主要组成部分,而狭性分布物种仅在常绿乔木林和灌丛中分布.以上结果表明,人类活动所造成的生境改变对鸟类多样性有不利影响.     

鄱阳湖都昌候鸟自然保护区丰水期和枯水期鸟类多样性

2009年12月和2010年5月,利用样线法和同步调查法对江西省鄱阳湖都昌候鸟自然保护区的鸟类开展了调查,分析了丰水期和枯水期鸟类群落结构的特征及其差异.野外调查共记录到鸟类14目43科169种.丰水期鸟类有36科96种,枯水期鸟类36科135种.其中,国家重点保护鸟类17种.结合保护区日常监测到白鹤(Grus leucogeranus)、灰鹤(G.grus)、白头鹤(G.monacha)和白枕鹤(G.vipio)的分布记录,该保护区鸟类累计达173种.保护区枯水期鸟类以雀形目、鹆形目和雁形目为主,分别占枯水期鸟类种类总数的47.4％、13.3％和9.6％;丰水期鸟类以雀形目、鸻形目和鹳形目为主,分别占鸟类种类总数的58.3％、8.3％和10.4％.枯水期和丰水期鸟类物种组成存在明显的季节性变换.枯水期农田生境鸟类多样性最高,其次是草洲、沼泽和水体,泥滩生境鸟类多样性最低;丰水期农田和水体生境鸟类多样性基本相同.都昌候鸟自然保护区枯水期的优势种为八哥(Acridotheres cristatellus)、白头鹎(Pycnonotus sinensis)、灰椋鸟(Sturnus cineraceus)、麻雀(Passer montanus)和山斑鸠(Streptopelia orientalis),丰水期为白鹭(Egretta garzetta)和八哥.     

三峡重庆库区不同鸟类群落的物种组成及多样性研究

1996～1997年,对三峡工程重庆库区的鸟类群落物种组成和种群数量进行了调查,共调查记录库区鸟类15目48科226种,数量18929只。用鸟类数量级划分、Sorensen相似性指数、Shannon-Wiener指数和Pielou指数分析库区各种生境鸟类群落物组成和物种多样性结果表明：1）库区天然林、人工林、灌草丛和水域生境中鸟类群落的组成与农田生境具有较高的相似性,尤以人工林和农田的相似性最高;2）库区人工林生境鸟类群落物种多样性最高;3）库区由于长期以来人类活动的影响,生境日趋单一,已逐渐形成一种以农田灌丛鸟类为主的鸟类生态系统。     

上海城市绿地冬季鸟类群落特征与生境的关系

2005年11月至2006年2月对上海市区绿地鸟类进行了调查,共记录到鸟类34种,隶属5目16科。研究发现冬季鸟类群落结构相对稳定,优势种为麻雀(Passer montanus)和白头鹎(Pycnonotus sinensis)。冬季鸟类群落多样性受多种因素的影响,其中绿地面积、乔木盖度和栖息地类型多样性是影响鸟类多样性的关键因子。聚类结果表明,面积大、生境类型丰富及人为干扰相对较少的绿地,鸟类多样性高。因此提出如下建议:(1)增加城市中植物种类,特别是乡土物种,适当提高冬季常绿乔木以及乔、灌、草的比例;(2)在绿地中尽可能多地保留自然生境;(3)在城市绿地中适当开辟湿地生境,以吸引水鸟栖息。     

四川南充高坪机场秋冬季节鸟类多样性与鸟撞预防

2006年9月-2007年2月,对四川南充高坪机场及其周围4种生境(草地、农耕区、村囤、松林)的鸟类进行调查,并进行鸟类多样性指数分析.结果共记录到鸟类81种,隶属于13目37科;秋冬季农耕区和村囤的鸟类密度、数量明显比草地和松林高;机场草地冬季鸟类的密度明显比秋季高.结合鸟类的生活习性及其栖息生境、Ⅳ值、分布广度和在各生境中的优势密度和总范围里的密度,秋季对鸟撞最具危险的是白鹭、家鸽、山斑鸠、白鹡鸰、白头鹎、小云雀、小鹀等;冬季对鸟撞最具威胁的是家鸽、小云雀、小鹀、金翅雀、白头鹎、水鹨等.并相应提出了相应一些的预防措施,如减少结实的植物、剪草降低草高、控制土壤动物的密度等.     

遥感与GIS支持下的崇明东滩迁徙鸟类生境适宜性分析

崇明东滩鸟类自然保护区位于长江入海口,是国际迁徙鸟类重要的栖息地.受自然和社会因素影响,该地区鸟类栖息环境正处于快速变化.研究采用面向对象的图像分割方法提取鸟类生境适宜性多边形评价单元,根据近年来野外调查数据分析了影响迁徙鸟类生存的地类、植被、潮沟、底栖生物等关键环境因素,建立了鸟类与关键环境影响因素的定性定量关系.在此基础上利用GIS空间分析方法和技术,进行了崇明东滩鸟类保护区内主要四大鸟类种群雁鸭类、鸻鹬类、鹭类以及鸥类的生境适宜性分析.结果表明:(1)崇明东滩迁徙鸟类生境较适宜的面积占保护区总面积40%左右;(2)光滩区域、与光滩邻近的海三棱藨草带以及潮沟地带是鸟类生境适宜性较好的地理区域;(3)基于面向对象的遥感分析技术和GIS空间分析技术,能有效且简便地对生态环境处于快速动态变化中的物种生境适宜性进行快速、客观准确的分析评价,其结果可为崇明东滩鸟类种群及其生存环境规划、保护和管理提供基础科学依据.     

南陵县扬子鳄的种群数量及栖息地质量

1986-1998年,在安徽省南陵县对扬子鳄种群资源及分布区栖息地状况进行了4次调查。1999年对该县扬子鳄部分栖息地的质量做了研究。结果显示,南陵县扬子鳄野生种群目前只30头左右,每4年平均递减率约38%,分布于6个镇,7个行政村中,75%的栖息地已经消失,其中东河、三里、石铺三镇生活有全县80%的扬子鳄,而石铺镇扬子鳄密度最大,引起扬子鳄种群数量下降的主要原因是栖息地破坏,同时对鳄的捕杀,污染、天灾也是重要因素,其野外栖息地主要为两种类型,农耕区普通池塘和丘陵山地的山塘、水库,耕作区食物,栖息条件较好,人鳄矛盾较小的局部水域依然是扬子鳄最佳选择,但这类水域农药化肥污染已构成对扬子鳄的潜在威胁。     

黄淮平原农业景观鸟类多样性及生境差异

农业景观中的鸟类多样性对生态系统功能和服务的形成与维持具有重要作用。黄淮平原区是我国最重要的农业景观区之一,为探讨区域内农业景观中鸟类多样性特征和不同生境间的差异,在研究区农业景观不同生境中布设样点,调查繁殖期鸟类多样性特征。结果显示:(1)共记录到32科、49属、66种的10044只个体,但优势科属明显;(2)物种丰富度、多样性和均匀度均表现出在沟渠、湖泊生境中较高,农田和村庄生境中相对较低,但物种多度呈现出村庄生境中最高,其次是沟渠和农田生境,湖泊生境中最低;(3)在区系分布上,各生境中均以广布种为主,生态类群上,鸣禽在各生境中均占绝对优势,涉禽和游禽主要分布在沟渠和湖泊生境中,从居留型来看,留鸟是各生境中的主导类群,候鸟、旅鸟和迷鸟比例很低;(4)鸟类群落异质性分析显示,各生境间的相似性总体上较高,表明区域内农业景观中鸟类组成具有较高的重叠性。研究显示农业景观中湖泊和沟渠的存在能有效的提高区域鸟类的丰富度和多样性,而沟渠的存在能有效的提高鸟类个体多度,农田和村庄有助于特定类群多度的增加,因此在未来的区域持续农业景观的构建中一方面要重视自然、半自然非农生境的作用,另一方面也不能忽视不同生物类群对景观异质性响应和对生境特征需求的差异。     

Assessing nursery habitat quality for native smelts (Osmeridae) in the low-salinity zone of the San Francisco estuary

Habitat quality was assessed for two native osmerids, delta smelt Hypomesus transpacificus and longfin smelt Spirinchus thaleichthys , between two distinct nursery areas located in the low-salinity zone of the San Francisco estuary. The relationship between several variables was investigated including fish density, fish size, feeding success and the general condition of larvae as well as juveniles for both species. The nursery habitats that were evaluated included the North and South Channels of Suisun Bay. The results showed higher densities of zooplankton and decreased water velocities for the North Channel when compared to the South Channel. The dominant prey item was calanoid copepod Pseudodiaptomus forbesi for both species although longfin smelt residing in the North Channel also included another copepod in their diets, Acanthocyclops spp. In both locations, delta smelt fed predominantly during daytime flood tides, while longfin smelt feeding appeared to continue into the night hours. When both locations were compared, delta smelt in the North Channel exhibited higher densities, larger sizes, increased somatic condition and larvae <15 mm standard length demonstrated greater feeding success. Longfin smelt, exhibited similar densities, feeding success and size distributions between both channels, but generally showed poorer somatic condition for the South Channel, potentially due to energetic costs associated with documented vertical migration behaviour. Overall, the physical conditions of the North Channel provided superior habitat for both species, while the South Channel afforded only marginal habitat for longfin smelt and very poor habitat for delta smelt. Therefore, the North Channel of Suisun Bay acts as critical nursery habitat by providing better feeding and growing conditions leading to increased health and survival for both species.     

Habitat change in braided flood plains (Tagliamento, NE-Italy)

1. Relative changes and age distribution of habitats were investigated in the active channel of a bar‐braided and an island‐braided reach of the Tagliamento River (NE‐Italy). Between September 1999 and January 2002, six habitat types were delineated with a differential Global Positioning System on five dates following floods of different magnitude. Overlay maps were employed to calculate age and relative change of habitats. We established exponential decay rates (k‐values) for islands and major aquatic habitats. 2. Relative changes of all aquatic habitats combined were up to 82% between survey dates in the bar‐braided flood plain, with a cumulative rate of 85% over the 2.5‐year period. Relative habitat changes in the island‐braided flood plain were lower with a cumulative change of almost 60% during the study period. In the bar‐braided flood plain significant exponential decay relationships were established for channels, alluvial channels, backwaters, and ponds. 3. Half‐lives were particularly short for backwaters and ponds. In the island‐braided reach, significant relationships existed for channels and alluvial channels. The half‐lives of channels and alluvial channels increased with the presence of vegetated islands. Relative habitat composition within the active corridor remained almost constant, supporting the applicability of the shifting mosaic steady state model to braided floodplain ecosystems. 4. Our results indicate that under natural conditions aquatic floodplain habitats can be highly dynamic over short time‐scales. Even small water level fluctuations (‘flow pulses’) can lead to major habitat changes with important consequences for the fauna and flora.     

Bird communities of natural and modified habitats in Panama

Only a small proportion of land can realistically be protected as nature reserves and thus conservation efforts also must focus on the ecological value of agroecosystems and developed areas surrounding nature reserves. In this study, avian communities were surveyed in 11 habitat types in central Panama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, shade coffee plantations, and residential areas supported the most species and individuals. Nearctic-Neotropical migratory species were most numerous in lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species compared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pastures, such that species richness in fallow pastures was similar to that found in wooded habitats. Community similarities were relatively low among all habitat types (none exceeding the observed 65% similarity between extensive and fragmented lowland forests), but communities in shade coffee and residential areas were 43% and 54′% similar to lowland forest fragments, respectively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in native forests. These same guilds also were better represented in fallow than in grazed pastures. Raptors and piscivorous species were most prevalent in cattle pastures and rice fields. These results, though based upon only species richness and abundance, demonstrate that many human-altered habitats have potential ecological value for birds, and conservation efforts in tropical areas should focus greater attention on enhancement of agricultural and developed lands as wildlife habitat. To understand the true conservation value of these modified lands will require examination not only of numbers but also of the types of species supported by these habitats, their reproductive output and survival rates.     

Conservation potential of semi-natural habitats for birds in intensively-used agricultural landscapes

Agricultural intensification resulted in substantial loss of farmland biodiversity. Semi-natural habitats may be viewed as potential buffers of these adverse impacts, but a rigorous assessment of their capacity for supporting farmland biodiversity is lacking. In this study, we explored conservation potential of two different types of semi-natural habitats for birds in intensively-used agricultural landscapes – farmland hedges (i.e., linear strips of shrubby and tree vegetation) and open scrubland (i.e., scattered shrubs and abandoned orchards). Specifically, we tested whether the abundance and species richness of birds differ between these habitats considering various species traits, such as habitat affinity (i.e., forest, farmland and urban species), diet specialization (i.e., animal eaters, plant eaters, and omnivores) and conservation status (Species of European Conservation Concern). We found that open scrubland hosted on average 37.9 bird species and 122.6 individuals per 1 km² of the transect, whereas farmland hedges hosted only 19 species and 61.8 individuals per 1 km² of the transect. However, results have substantially changed if we considered the area of suitable habitat into account. More specifically, open scrubland hosted more bird species and individuals when we considered open habitat species and the area of open habitats, whereas farmland hedges had higher species diversity and individuals of woodland bird species when we considered the area of woodland habitats. Similarly, analyses of habitat affiliations of individual species corresponded to the whole-community patterns; and revealed that several woodland bird species were mainly associated with farmland hedges (e.g., Chaffinch Fringilla coelebs, Common Nightingale Luscinia megarhynchos and Blackcap Sylvia atricapilla), whereas the open scrubland was preferred by open habitat bird species (e.g., Corn Bunting Emberiza calandra, Quail Coturnix coturnix and Skylark Alauda arvensis). These results demonstrate that semi-natural habitats, both open scrubland and farmland hedges, have large potential for promotion and conservation of bird communities within intensively used agricultural landscapes, as both may have represented suitable habitats for species with different ecological requirements. Therefore, management measures focused on the enlargement of the area of these habitats, in combination with suitable management (e.g., regulating the progress of natural succession in open scrubland; increasing structural diversity of existing farmland hedges), may substantially contribute to bird conservation within agricultural landscapes.     

Starling foraging success in relation to agricultural land-use

Changes in agricultural land-use have been suggested to contribute to the decline of several bird species through negative effects on their food supply during breeding. One important change in land-use has been loss of pastures, especially permanent pastures. In this study we investigated how different forms of agricultural land-use affected foraging success of a declining bird species, the European starling Sturnus vulgaris . We let caged starlings forage in different forms of agricultural fields and determined time spent foraging and foraging success. The starlings' activity level (time spent actively foraging) as well as the number of prey caught per time unit was strongly related to the abundance of prey in soil samples. Also the body mass change during the experiment was positively related to activity level and prey capture rate. We found consistent differences in foraging variables between habitats. In spring sown grain starlings were least active and found fewer prey items at a lower rate than in any other habitat. The other three habitats differed less, but in general mowed hay fields appeared slightly more valuable than the cultivated and natural pastures. We did not find any differences between natural and cultivated pastures in foraging variables. Thus, starling foraging success is higher in grass-covered fields than in cultivated fields, but the management of the grass-covered fields mattered less. The results are consistent with starlings having higher population densities and breeding success in areas with higher availability of pasture. We suggest that the physical structure of the habitat (sward height) and moisture may be additional variables that need to be taken into account to explain starling breeding density and success in the agricultural landscape.     

Response of double-crested cormorants to a large-scale egg oiling experiment on Lake Huron

We report on a management experiment examining the effects of large-scale egg oiling on double-crested cormorant nest abundance and measures of seasonal cormorant density (bird-days/km²) from 2000 to 2005. We employed the staircase design to distinguish transient responses to management treatments from site and year effects that generally contribute to variation in populations. The response to egg oiling in Georgian Bay was as expected with a decline in nest abundance attributable to egg oiling. In the North Channel, nest abundance did not decline because of egg oiling but increased, reflecting either retention of nesting adults or recruitment to colonies. This surprising outcome may stem from fish escapement from pen rearing facilities in the vicinity of the oiling experiment in the North Channel. We observed no effect of egg oiling on the July–August seasonal density of cormorants. The strongest effect size was associated with site effects followed by year effects for nest abundance and seasonal density. The effect size of egg oiling on variation in nest abundance did not exceed 5% for any year in both the North Channel and Georgian Bay. Fish pen culture appears to affect coastal distribution of cormorants. © 2011 The Wildlife Society.     

Short-term effects of a catastrophic beaver dam collapse on a stream fish community

Synopsis We examined the short-term effects of the natural catastrophic collapse of a beaver dam on downstream benthic insect density and fish community structure in a headwater tributary of the Mississippi River. The catastrophic collapse of the dam and ensuing flash flood resulted in a dramatic (< 90%) decrease in benthic insect density in riffle and pool habitats. Sixty days after collapse of the dam, insect densities in riffles were 62% of pre-collapse densities. Insect recolonization of pools was slower than for riffles; 60 days after collapse of the dam insect densities in pools were 8% of pre-collapse levels. Collapse of the beaver dam altered the structure of the downstream fish community by causing a short-term (2–4 days) influx of pond species, resulting in a brief increase in species richness and abundance. Fish species richness and abundance then decreased for 4–60 days to levels below those prior to the collapse.     

贺兰山岩羊冬春季取食生境的比较

2003年11～12月和2004年4～6月,在贺兰山设定了25条固定样线,采用直接观察法对岩羊冬春季的取食生境选择进行了研究。结果表明,岩羊冬季对12种取食生境生态因子有选择性,偏爱选择位于山地疏林草原带,优势乔木为灰榆,乔木密度〈4株、高度4～6m,灌木密度〉5株、高度〉1．3m,食物质量〉50g,人为干扰距离〈500m,距裸岩距离〈2m的地方取食。而春季对11种取食生境生态因子有选择性,偏爱选择山地疏林草原带,优势乔木为灰榆,乔木密度〈4株、高度〈6m,灌木密度5～10株、高度1．3～1．7m,食物质量〉100g,海拔高度〈2000m,距水源距离〈500m,隐蔽级50％～75％的地点。冬春季岩羊对植被类型、地形特征、优势乔木、乔木密度、乔木高度、灌木密度、灌木距离、食物丰富度、坡向、坡度、距水源距离、人为干扰距离和隐蔽级的选择存在显著差异。主成分分析表明,冬季第1主成分的贡献率达24．493％,其中绝对值较大的权系数出现在植被类型、优势乔木、乔木高度、乔木距离、灌木密度、灌木高度、海拔高度、距水源距离和人为干扰距离等生态因子：春季第1主成分的贡献率达28．777％,其中绝对值较大的权系数出现在植被类型、乔木距离、灌木高度、灌木距离、食物丰富度、海拔高度和人为干扰距离等生态因子。随着北方地区冬春季食物数量和质量的剧烈变化,贺兰山岩羊对取食生境的利用对策也将发生一定程度的改变,与其他分布区的岩羊相比,贺兰山独特的地理位置和特殊生境使其在取食生境选择上存在很大差异。