冬季水鸟对崇明东滩水产养殖塘的利用

自然湿地的丧失和退化给依赖湿地生存的水鸟带来了严重威胁,人工湿地作为水鸟栖息地的功能日益受到关注.水产养殖塘是人工湿地的重要类型之一.通过研究崇明东滩水产养殖塘冬季水鸟群落组成及其栖息地特征,发现大面积养殖塘比小面积养殖塘吸引更多种类和更高密度的水鸟.养殖塘在放水前水位较高时吸引更多游禽栖息,而在放水后水位较低时吸引更多涉禽;在放水过程中,养殖塘中水鸟的种类最多,密度最大.另外,在放水的不同时期,不同的环境因子对水鸟群落的影响不同:放水之前,养殖塘水面面积和平均水深是水鸟种类和数量的主要影响因子,其中游禽种类和数量受水面面积影响较大,涉禽种类和数量受平均水深影响较大;放水过程中,裸地面积、芦苇面积、干扰程度、平均水深和水深变异对水鸟、游禽和涉禽的种类和数量起主要作用;放水之后,水深变异对水鸟种类和数量的影响较大,而影响游禽种类和数量的主要因子是水面面积,影响涉禽种类和数量的主要因子是水深变异.研究表明,通过对影响水鸟栖息地利用的主要因子的有效管理,养殖塘在提供经济效益的同时也能为水鸟提供适宜的栖息地.     

安徽沿江浅水湖泊越冬水鸟群落的集团结构

长江中下游湖泊是越冬水鸟的重要栖息地,随着湖泊渔业养殖强度的不断加大,湖泊湿地严重退化,水鸟的越冬生态受到影响。为揭示长江中下游浅水湖泊越冬水鸟对湿地资源的利用特征,2008年12月至2009年3月,通过扫描取样法采集安徽省长江沿江升金湖、菜子湖和武昌湖3个浅水湖泊30种越冬水鸟的取食行为百分比数据,利用聚类分析法对越冬水鸟进行集团划分,并采用无倾向对应法(DCA)分析越冬水鸟的取食特征。聚类分析结果表明,安庆沿江湖泊越冬水鸟群落可分为4个集团,即深水取食集团G1、挖掘和啄取集团G2、浅水取食集团G3和泥滩拾取集团G4。G2集团的鸟种最多,共有13种,优势种为鸿雁(Anser cygnoides)、豆雁(Anser fabalis);G3集团次之,共6种,优势种为小天鹅(Cygnus columbianus)、白琵鹭(Platalea leucorodia);G4集团共5种,优势种为黑腹滨鹬(Calidris alpina)、鹤鹬(Tringa erythropus)和红脚鹬(Tringa totanus);G1集团水鸟种类有6种。这些水鸟的觅食生境主要在湖泊滩涂和浅水区域,其食物资源的可利用性和觅食对策共同决定群落组成结构。DCA分析表明,取食方式及取食时运动方式组成的觅食对策决定了集团食物资源的分割,草滩中取食鸟类主要采用静止取食和啄取方式,泥滩取食集团主要采取拾取及奔-停取食,深水区取食集团则主要采用潜水方式取食,因此,维持湖泊不同区域的丰富食物资源对于保护湖泊丰富的水鸟资源具有重要意义。     

围填海对湿地水鸟种群、行为和栖息地的影响

湿地水鸟是湿地生态系统的重要组成部分。由于水鸟对湿地环境的变化较为敏感,所以被认为是监测湿地环境质量的指示生物。围填海严重破坏了湿地生态环境,对水鸟的种群、行为和栖息地利用产生了重大影响。本文从种群生态方面分析围填海对鸟类种群数量和多样性的影响;从水鸟行为方面归纳围填海对鸟类取食行为、繁殖行为、迁徙行为、社群行为的影响;从水鸟栖息地利用方面探讨围填海对水鸟栖息地利用和适宜生境选择的影响。围填海通常会降低生境专性鸟类种群数量,但对生境泛性鸟类的种群数量影响较小。围垦强度决定着鸟类多样性大小。适度的围垦使得生境多样化,有利于鸟类多样性的增加;过度的围垦则使得水鸟生境破碎化,从而导致多样性下降。围填海后的生境状况影响着水鸟的取食、繁殖、迁徙、社群行为及栖息地的选择。滩涂面积的减少以及植被群落的改变不利于涉禽的觅食栖息,而养殖塘等人工湿地则为游禽提供了丰富的食物来源以及良好的栖息环境。扩大研究的时空尺度可全面分析围填海对鸟类的影响机制;将多种水鸟结合在一起并分析其对围填海的响应机制应是未来研究的热点。     

骨顶鸡等游禽对不同人为干扰方式的响应

分别于2008年4月至6月和2009 年4月至6月, 采用目标动物取样法在黑龙江省安邦河湿地和大庆龙凤湿地研究了骨顶鸡等水鸟对人为干扰的行为响应。结果表明:骨顶鸡对行人和机动车辆两种干扰的反应距离类似,但耐受程度有所不同,骨顶鸡对机动车辆干扰的耐受性要好于行人干扰。在以游客等行人干扰为主的安邦河湿地,骨顶鸡以及其他游禽对干扰产生行为反应的比例要高于以机动车辆干扰为主的龙凤湿地,说明相对于行人干扰骨顶鸡对机动车辆更容易耐受;在安邦河湿地,骨顶鸡对划船的反应距离以及反应程度要大于人行走,说明骨顶鸡对于侵入性的干扰更为敏感。此外,对凤头(Podiceps cristatus)、黒颈(Podiceps nigricollis)、小(Tachybaptus ruficollis)、黑水鸡(Gallinula chloropus)、红头潜鸭(Aythya ferina)、赤膀鸭(Anas strepera)、绿头鸭(Anas platyrhynchos)、斑嘴鸭(Anas poecilorhyncha)、绿翅鸭(Anas crecca)、白眉鸭(Anas querquedula)、赤颈鸭(Anas penelope)、琵嘴鸭(Anas clypeata)等游禽对人为干扰的反应距离、耐受距离以及遭受干扰时的反应比例进行了研究,结果显示3种对干扰的耐受距离差异不显著,12种鸭类中红头潜鸭对人为干扰的敏感性要小于其他鸭类,斑嘴鸭和绿头鸭则相对敏感。     

鄱阳湖四种水鸟的栖息地利用与水深和食物的关系

为了了解水深和食物资源对水鸟栖息地利用的影响,2012 ~ 2013年越冬期,采用样方法,对鄱阳湖沙湖的白鹤 (Grus leucogeranus)、小天鹅 (Cygnus columbianus)、东方白鹳 (Ciconia boyciana) 和白琵鹭 (Platalea leucorodia) 4种水鸟的数量、觅食地和休息地的水深以及主要食物——沉水植物冬芽的密度和生物量进行了调查。每个样方为150 m? 150 m的栅格,全湖共设置152个样方。结果显示,10月份沉水植物冬芽的平均水深为 (124.2 ± 12.0) cm。4种水鸟觅食地的水深均显著高于其休息地的水深 (白鹤：Z = 11.96, 小天鹅：Z = 4.69, 东方白鹳：Z = 14.44, 白琵鹭：Z = 29.33, 所有P < 0.01);对于2种食冬芽的水鸟,白鹤觅食地的水深、冬芽生物量、取食深度以及休息地水深均显著低于小天鹅 (觅食地水深: Z = 8.56, 冬芽生物量: Z = 2.93, 取食深度: Z = 14.69, 休息地水深: Z = 4.34, 所有P < 0.05),但两者觅食地的冬芽密度差异不显著 (Z = 0.6, P = 0.55);对于2种食鱼性水鸟,东方白鹳觅食地水深、取食深度和休息地水深均显著大于白琵鹭 (觅食地水深: Z = 10.60; 取食深度: Z = 9.35; 休息地水深: Z = 8.47, 所有P < 0.01)。回归分析表明,白鹤、东方白鹳、白琵鹭的觅食个体数量均与水深呈二次项关系,个体数量最大的觅食地水深分别为23.9 cm,33.0 cm和22.6 cm;白鹤、小天鹅的觅食个体数量均与冬芽生物量呈线性关系。3种涉禽均只能分布在一定的水深范围内,且同种食性的水鸟利用不同的水深从而减少在空间生态位的重叠。     

黄渤海濒危水鸟栖息地动态变化研究

中国滨海湿地是东亚-澳大利西亚迁徙路线上候鸟重要的停歇地、繁殖地和越冬地,土地利用变化所引发的滨海湿地退化导致水鸟栖息地类别和面积发生了很大转变,影响迁徙水鸟种群数量的稳定性。然而,土地利用变化在哪些区域和多大程度上影响了迁徙水鸟的栖息地分布尚不清晰。以土地围垦典型区域黄渤海滨海湿地为研究区,以受胁濒危水鸟物种勺嘴鹬、大滨鹬、大杓鹬、小青脚鹬、黑脸琵鹭、黄嘴白鹭、遗鸥、黑嘴鸥为研究对象,结合物种分布模型MaxEnt和GIS空间分析,模拟2000、2015、2020年水鸟栖息地时空分布,探索过去20年栖息地分布的时空变化,分析水鸟种群变化趋势,识别水鸟栖息地保护优先区域,提出水鸟栖息地保护管理建议。结果显示：2000—2020年,8个水鸟物种栖息地主要分布在渤海湾、莱州湾、江苏盐城沿岸、如东-东台沿岸区域。所有物种的栖息地面积均呈不同程度的下降趋势,其中7个物种栖息地下降比例超过50%,下降的区域主要分布在渤海湾、江苏盐城沿岸、东台条子泥、小洋口沿岸,滨海湿地丧失是导致水鸟栖息地面积下降的直接因素。7个物种种群数量呈下降趋势。研究所确定的水鸟保护优先区面积达240.32 km^2...     

基于遥感反演预测“引江济淮”工程对菜子湖越冬水鸟栖息地的影响

菜子湖位于“东亚-澳大利西亚”候鸟迁徙路线上, 为越冬水鸟提供重要的栖息地。“引江济淮”工程拟通过菜子湖调引长江水, 向巢湖和淮河输送水资源。工程实施后, 菜子湖冬季水位将明显抬升, 改变原有自然节律, 导致湿地景观格局发生重大变化, 可能对在此越冬的水鸟产生重要影响。结合遥感影像、水位季节动态及野外水鸟调查, 分析不同水位时各类湿地景观斑块的分布及面积, 预测工程实施后湖泊水位变化对越冬水鸟栖息地的影响。2016年和2017年两次同步调查共记录到水鸟49450只, 隶属于6目12科42种。菜子湖水位和湿地景观格局具有明显的季节动态, 10月份水位开始下降, 暴露多种湿地景观斑块, 泥滩和草滩面积随水位下降而增加, 为多种越冬水鸟提供觅食地。泥滩和草滩的分布具有空间异质性, 越冬水鸟的空间分布与此相适应。“引江济淮”工程实施后, 菜子湖冬季水位较高, 导致大量泥滩和草滩不能暴露, 越冬水鸟栖息地丧失严重, 如东方白鹳(Ciconia boyciana)(EN)、白鹤(Grus leucogeranus) (CR)、白头鹤(Grus monacha)(UV)和鸿雁(Anser cygnoides)(UV)等濒危物种。为降低工程对越冬水鸟栖息地的影响, 建议工程实施后菜子湖越冬期水位应不超过11.5米。     

中国大陆沿海水鸟栖息地保护优先区及空缺分析

中国大陆沿海湿地是东亚-澳大利西亚候鸟迁徙的重要停歇地,自然湿地丧失与退化已经严重威胁到水鸟生物多样性的稳定性,急需开展物种及其栖息地的保护工作。识别中国大陆沿海水鸟保护优先区,针对保护优先区进行保护优先等级划分,确定目前尚存的保护空缺,是针对性开展水鸟栖息地保护的前提。以中国大陆沿海11省、自治区、直辖市沿岸湿地为研究区,整合鸟类网站、水鸟调查报告和文献中的水鸟调查数据,采用热点分析方法,确定水鸟保护优先区,将每个地块上满足水鸟保护优先区识别标准的物种数量占所有地块中满足标准的物种数量最大值的比例划分成0.5 ≤ P_i ≤ 1、0.25 ≤ P_i < 0.5、0 < P_i < 0.25三个区间,确定对应的I类、II类和III类水鸟保护优先区保护优先等级;结合国家自然保护地名录,确定水鸟保护优先区保护空缺。结果显示：共有65块中国大陆沿海水鸟保护优先区,记录到满足热点分析标准的水鸟物种共76种,其中受胁物种18种。水鸟保护优先区保护优先等级属于I、II、III类的分别有8块、10块、47块,且水鸟保护优先区保护优先等级属于I、II类的地块集中分布在上海以北的区域,水鸟保护优先区保护优先等级属于III类的地块主要分布在上海以南的区域。38块水鸟保护优先区存在保护空缺,占总数的58.46%,这些保护空缺地中保护优先等级属于I类和II类的地块共6块,建议针对这些地块单独建立保护机构或纳入现有周边的保护体系中。     

越冬青头潜鸭的栖息地利用和行为时间分配

青头潜鸭(Aythya baeri)是世界极危级(CR)物种,2018年至今在河南民权黄河故道国家湿地公园均调查到稳定的青头潜鸭越冬种群。研究青头潜鸭对不同栖息地的利用方式及所受干扰有利于该物种的保护管理。本研究分析了越冬期不同栖息地及不同性别青头潜鸭的行为时间分配差异,以及人为干扰对青头潜鸭活动的影响。2020年12月采用焦点取样法对河南民权黄河故道国家湿地公园内青头潜鸭进行行为观察,按照青头潜鸭对栖息地的利用率,将其栖息地类型分为池塘、大水面荷塘和开阔水域。使用单因素方差分析(ANOVA)及t检验比较不同栖息地及性别间差异的显著性。青头潜鸭的主要行为是休息(44.4%)和觅食(34.2%),且在不同栖息地存在显著差异。池塘中的觅食行为占比(50.1%)显著高于大水面荷塘和开阔水域;大水面荷塘中的休息行为占比(63.1%)显著高于池塘和开阔水域。雌雄之间存在一定的行为差异,雌性觅食时间高于雄性,整理行为时间低于雄性,这种差异受栖息地的影响。三种类型栖息地均存在不同程度的人为干扰,池塘中所受干扰程度最高,主要干扰源为钓鱼、行人和施工,荷塘和开阔水域主要干扰为打渔船。本研究表明,对于越冬期的青头潜鸭,池塘是重要觅食地,荷塘可作为躲避干扰的休息场所,开阔水域可作为稳定的觅食栖息场所。对青头潜鸭的保护应考虑到不同栖息地的生态作用,以及青头潜鸭对不同干扰的容忍度,采取相应措施开展保护行动。     

鄱阳湖越冬鹤鹬的日间行为节律

目前有关鸟类越冬行为节律的研究主要集中在大型水鸟。与大型鸟类相比,小型鸟类在体温调节中消耗的能量更多,因此可能呈现不同的日间行为节律。本研究选择鄱阳湖数量较大的小型水鸟——鹤鹬Tringa erythropus为研究对象,于2014年11月—2015年3月在鄱阳湖的子湖——常湖池对越冬期鹤鹬各种行为的时间分配进行了调查研究。结果表明觅食(61.4%)和休息(32.1%)是鹤鹬越冬期最主要的行为,2种行为的比例呈显著负相关。与一些植食性水鸟相比,肉食性鹤鹬的觅食行为比例偏低。而与一些大型食肉性水鸟相比,鹤鹬的觅食行为比例偏高,这可能与其较小的体型在体温调节中消耗的能量较多有关。鹤鹬的警戒行为比例较低(0.8%),越冬期集大群的习性可能是导致其偏低的主要原因。越冬期不同月份间各行为比较中,1月出现了觅食行为比例的高峰和休息行为比例的低谷,这可能与1月平均气温为全年最低有关。觅食行为比例在全天呈缓慢上升趋势,而休息行为比例呈下降趋势。虽然觅食和休息行为的时间分配在全天有一定变化,但是鹤鹬的日间行为节律性并不强。鹤鹬的觅食行为主要发生在跗跖位(0~5.5 cm),而休息行为主要发生在跗跖上位(5.5~8.6 cm),安全性和食物的可利用性可能是影响鹤鹬生境选择的主要因素。     

崇明东滩抛荒鱼塘的自然演替过程对水鸟群落的影响

人工湿地抛荒的现象普遍存在,但针对抛荒后的自然演替过程对水鸟群落影响的研究较少.于2007、2008、2011年对崇明东滩自然抛荒的人工鱼塘水鸟群落展开调查,探究抛荒后的自然演替过程对水鸟群落结构及不同水鸟类群的影响.3a累计观察到水鸟59种12819只,隶属6目12科.其中抛荒前最多,共53种11001只;抛荒第1年22种1673只;抛荒第4年最少,9种145只.鱼塘抛荒后水鸟种类和数量下降剧烈,物种多样性先上升再下降,均匀度逐年上升,优势度先下降再上升.方差分析结果表明,5个群落特征都存在极显著年度差异(P1＜0.01;P2＜0.01;P3＜0.01;P4=0.003;P5＜0.01).非参数检验结果表明,不同类群水鸟的种类和数量逐年下降趋势明显,且年际差异极显著.即抛荒后的自然演替过程对水鸟群落产生了不利影响.建议采取人工管理措施防止旱化,增加环境异质性,恢复水鸟群落多样性.     

Wetland Suitability and Connectivity for Trans-Saharan Migratory Waterbirds

To complete their life cycle waterbirds rely on patchily distributed and often ephemeral wetlands along their migration route in a vast unsuitable matrix. However, further loss and degradation of remaining wetland habitats might lead to a configuration and size of stopovers that is no longer sufficient to ensure long-term survival of waterbird populations. By identifying optimal conservation targets to maintain overall habitat availability en route, we can accommodate an as yet absent functional connectivity component in larger management frameworks for migratory waterbirds, such as the Ramsar Convention and the EU Natura 2000 Network. Using a graph-based habitat availability metric (Equivalent Connected Area) we determine the functional connectivity of wetland networks for seven migratory waterbirds with divergent habitat requirements. Analyses are performed at two spatial extents both spanning the Mediterranean Sea and centered around Greece (Balkan-Cyrenaica and Greece-Cyrenaica). We create species-specific suitable habitat maps and account for human disturbance by species-specific disturbance buffers, based on expert estimates of Flight Initiation Distances. At both spatial extents we quantitatively determine the habitat networks’ overall functional connectivity and identify wetland sites that are crucial for maintaining a well-connected network. We show that the wetland networks for both spatial extents are relatively well connected and identify several wetland sites in Greece and Libya as important for maintaining connectivity. The application of disturbance buffers results in wetland site-specific reduction of suitable habitat area (0.90–7.36%) and an overall decrease of the network’s connectivity (0.65–6.82%). In addition, we show that the habitat networks of a limited set of species can be combined into a single network which accounts for their autoecological requirements. We conclude that targeted management in few but specific wetland complexes could benefit migratory waterbird populations. Deterioration of these vital wetland sites in Greece and Libya will have disproportionate consequences to the waterbird populations they support.     

Trends in the use of a small coastal lagoon by waterbirds: Muni Lagoon (Ghana)

This paper presents data from a twelve-year (1986–98) monitoring of waterbird populations at Muni Lagoon, and discusses the ornithological importance of the lagoon and trends in the use of the site by waterbirds. The small brackish lagoon forms part of the Muni-Pomadze Ramsar site situated on the Ghana coast. A total of 48 species of waterbirds were recorded at the site comprising of 29 species of waders, eight species of terns, two species of gulls, seven species of herons and egrets, one species each of duck and cormorant. The most abundant waterbirds species recorded on the site were the Curlew Sandpiper, Ringed Plover, Greenshank, Black-winged Stilt, Common Tern, Black Tern, Royal Tern and the Sandwich Tern. Three species of waders, Black-winged Stilt, Pratincole and Little Tern were observed to breed at the site. The highest numbers of waterbirds occurred on the site in the period September to March. The site remains an internationally important wetland site by virtue of supporting internationally important numbers of four species of terns: Royal Tern, Sandwich Tern, Common Tern and Black Tern. The value of Muni lies more in its use as a feeding/staging site for migrating waders that spend the non-breeding season in Ghana or pass through to winter further south, and as a roosting site for terns which feed mainly at sea. The use of the site by waterbirds has increased by some 400% between 1986 and 1998. This is attributed to improved prey availability resulting from the opening of the lagoon into the sea during the 1994 floods, and reduced disturbance of feeding and roosting birds. This would imply that the value of the site as waterbird habitat could improve considerably with appropriate habitat management interventions and continued protection.     

Nestedness theory suggests wetland fragments with large areas and macrophyte diversity benefit waterbirds

Many artificial wetland constructions are currently underway worldwide to compensate for the degradation of natural wetland systems. Researchers face the responsibility of proposing wetland management and species protection strategies to ensure that constructed wetlands positively impact waterbird diversity. Nestedness is a commonly occurring pattern for biotas in fragmented habitats with important implications for conservation; however, only a few studies have focused on seasonal waterbird communities in current artificial wetlands. In this study, we used the nestedness theory for analyzing the annual and seasonal community structures of waterbirds in artificial wetlands at Lake Dianchi (China) to suggest artificial wetland management and waterbird conservation strategies. We carried out three waterbird surveys per month for one year to observe the annual, spring, summer, autumn, and winter waterbird assemblages in 27 lakeside artificial wetland fragments. We used the NeD program to quantify nestedness patterns of waterbirds at the annual and seasonal levels. We also determined Spearman partial correlations to examine the associations of nestedness rank and habitat variables to explore the factors underlying nestedness patterns. We found that annual and all four seasonal waterbird compositions were nested, and selective extinction and habitat nestedness were the main factors governing nestedness. Further, selective colonization was the key driver of nestedness in autumn and winter waterbirds. We suggest that the area of wetland fragments should be as large as possible and that habitat heterogeneity should be maximized to fulfill the conservation needs of different seasonal waterbirds. Furthermore, we suggest that future studies should focus on the least area criterion and that vegetation management of artificial wetland construction should be based on the notion of sustainable development for humans and wildlife.     

Waterbird assemblages and associated habitat characteristics of farm ponds in the Western Cape, South Africa

Natural freshwater wetlands are among the most threatened habitats on Earth. Effective wetland biodiversity conservation can not, however, be evaluated without fully understanding the roles of artificial waterbodies as refuges for water-dependent plants and animals. Waterbird assemblages were examined on 59 farm ponds in the Elgin and Caledon districts of the Western Cape, South Africa. This study examines the relationship between waterbird use and habitat characteristics of farm ponds. Patterns of temporal and spatial variation of waterbird species richness and abundance were quantified in relation to the habitat characteristics of each pond. Cluster analysis and multiple regression analyses identified surface area of the farm ponds as an important variable determining the presence and abundance of many waterbird species. Structural diversity in terms of vegetation in and around the ponds was especially important in determining their usage by waterbirds. These variables were evaluated in terms of creating a mosaic of habitat types (by varying vegetation structure and pond topography), which may be a useful way to enhance waterbird diversity at farm ponds. This study concludes that the high number of farm ponds in the transformed habitat matrix of the Western Cape plays an important role in conserving waterbirds.     

Long‐term declines in multiple waterbird species in a tidal embayment,south‐east Australia

Worldwide, local extinctions and severe declines in waterbird densities are being reported from many important waterbird sites. Waterbird sites often exist as a network, collectively providing crucial habitat for different life history stages of different species. Therefore, population changes at one site may strongly influence others. In Australia, many waterbird species are highly mobile, and move rapidly over long distances in response to rainfall. Large tidal wetlands often serve as drought refugia or alternative breeding habitat for these species. These sites are also the migration terminus of many species of shorebirds that spend their non‐breeding season in Australia. One such site in south‐eastern Australia is Western Port, a Ramsar‐listed tidal embayment forming part of the East Asian–Australasian Shorebird Site Network. We measured waterbird population trends over nearly 40 years in Western Port to see whether changes showed consistent trends over time across multiple species. Thirty‐nine species were recorded often enough to allow an analysis of trends over time using dynamic linear models and, where appropriate, piecewise linear regression. Twenty‐two species had declined, including four species of duck, five species of fish‐eating bird (cormorants, terns and pelicans), one species each of grebe, gull and heron, and 10 species of shorebird. Only two species (Australian pied oystercatcher Haematopus longirostris and straw‐necked ibis Threskiornis spinicollis) increased significantly over the same time period. Patterns of decline in non‐migratory waterbirds may reflect diminishing wetland availability, local reductions in fish prey, increased predation pressure and changes in inland wetland resources. Declines in migratory shorebirds are most likely related to loss of habitat elsewhere in their trans‐equatorial migration routes. These trends in waterbirds that use Western Port reflect widespread impacts on populations elsewhere in Australia and overseas, necessitating more than simply local management of this tidal embayment.     

西藏夯错水鸟多样性及斑头雁繁殖活动区的变化

于2009年4 11月,对西藏夯错的水鸟资源状况进行了调查,旨在了解该地区水鸟资源状况的了解,并为禽流感的防控提供了科学依据。在夯错全年共记录到水鸟26种,隶属于6目10科。夯错也是斑头雁和棕头鸥重要的繁殖地。水鸟春秋季迁徙高峰期在4月份和10月份,这也是水鸟多样性较高的2个月,其主要原因是由于迁徙鸭类数量和种类的增加。卫星跟踪研究表明,在繁殖前期,斑头雁活动区面积较大,主要在夯错及其周围的湿地取食;进入繁殖中期,斑头雁的活动范围减少了许多;繁殖后期,随着幼鸟陆续出壳,父母随即带领幼鸟离开夯错,到其它湿地取食和育雏,因此此期的活动区面积较大。由于夯错面积较小,不能满足斑头雁对食物的需求,因此部分斑头雁选择其它湿地作为主要的取食地,但部分扩散到其它湿地的斑头雁在迁徙前期重新返回夯错,使得该时期斑头雁的数量有呈上升趋势。通过与青海湖水鸟资源状况的比较发现,夯错水鸟种类较少,这可能主要是由于两个湖泊所处地理区划的不同,并由此带来的气候环境的差异,以及植被条件的不同所造成的。这种差异主要是由于夯错海拔较高,紫外线很强,气候干燥,植被单一,栖息地类型多样性较低,因此水鸟的种数也相对较少一些。     

Habitat use and diversity of waterbirds in a coastal lagoon around Lake Biwa, Japan

We investigated habitat use and diversity of waterbirds at one of the coastal and satellite lagoons around Lake Biwa, which is a registered wetland of the Ramsar Convention in Japan. To evaluate the importance for waterbirds of a lagoon around the freshwater lake, we conducted 26 censuses over 1 year on seven blocks with different landscape elements in a small lagoon. A total of 25 species were found and most of them (72%) belonged to a guild in which birds forage without diving. Species density (per ha) and diversity was high in blocks where Zizania latifolia Turcz and Phragmites australis L. reed beds existed. Not all of the waterbird species were feeding all the time, but were often resting in their preferred blocks, suggesting that they use the lagoon as both a refuge and a feeding site. Habitats with a structural reed bed community and shallow waters (<1 m depth) may be crucial determinants of high waterbird diversity in this small lagoon around which many people live.     

Community structure and association of waterbirds with spatial heterogeneity in the Bahia Magdalena-Almejas wetland complex, Baja California Sur, Mexico

Community structure and association of waterbirds with spatial heterogeneity in the Bahia Magdalena-Almejas wetland complex, Baja California Sur, Mexico. To test the hypothesis that spatial heterogeneity determines waterbird diversity in a coastal wetland, we compared waterbird density, diversity, and species composition among various habitats and landscapes units in Bahia Magdalena-Almejas, Baja California Sur, Mexico. Based on diversity patterns and bird distribution, we assessed the effect of coastal development on the waterbird community structure. To gather information on habitat features and waterbird populations we conducted waterbird censuses in 329 habitat segments along the internal coastline of the study area, from February 2002 to February 2003. We performed non-parametric analyses to test the null hypothesis of no diference on waterbird density, and diversity among landscape units and seasons. The species composition was evaluated using ordination techniques. Waterbird density was higher in winter and autumn in the three lagoons of the study area, particularly in the insular coast, sandy beach and dunes; it was higher in the few segments of antropic sustrate. Diversity was significantly higher in mangrove habitat along the peninsular coast, and in mangrove-dunes association on the insular coast. Although modification of coastal natural habitat and boat transit disturbance had no influence on waterbird density or diversity, the highest richness of waterbirds occurred in well preserved areas. Species composition analysis showed differences between Santo Domingo Channel and Magdalena Bay. Pelagic and mangrove habitat had a species composition difference higher than those associations in other habitats. Such differences in species assemblages by habitat and landscape units suggest that communities are structured according to the range of available natural resources in structurally complex habitats, and that dominant piscivorous waterbird species were favored in this community.