Low breeding success of the little egret (Egretta garzetta) near residential areas and in colonies exposed to gales: a comparison of colony in Sichuan,Southwest China,with literature

The breeding biology of the little egret (Egretta garzetta) was studied in 20 nests within the mixed-species breeding colonies at Nanchong, Sichuan, Southwest China, in 2006. By measuring a set of physical characteristics of vegetation at the nests and at a set of 20 randomly chosen sites we showed that birds preferentially used taller trees in areas with fewer shrubs of higher species diversity. Nests at lower locations in trees had marginally lower hatching success due to their destruction by humans; this destruction contributed marginally significantly to lowering of the total nesting success in all studied nests. Although gale winds also had a negative effect on breeding success, the anthropogenic influences were a greater factor in reproductive failure. We found similar effects in our review of literature on breeding success of the little egret from various geographical areas. Our results may be of use by conservation organizations in their actions to protect colonies of the little egret.     

西藏昌都发现白鹭

<正>2013年9月至2014年6月,笔者在西藏昌都市八宿县、贡觉县、芒康县和昌都县先后观察并拍摄到白鹭(Egretta garzetta),为西藏首次发现。2013年9月29日,在八宿县然乌镇政府后方的湖边(29°30′17.28″N,96°45′25.44″E,海拔3 934 m),观察到2只白鹭成鸟,其体形纤瘦,全身羽毛白色,头部无羽冠,肩、背和前胸的蓑状羽也消失,呈冬羽特征;虹膜为黄色;眼先黄绿;嘴黑色,但嘴裂处及下嘴基部显淡黄色;胫与跗跖部黑色,趾黄绿色。2014年5月至6月,     

A re-evaluation of management units based on gene flow of a rare waterbird in the Americas

The maintenance of gene flow in species that have experienced population contractions and are geographically fragmented is important to the maintenance of genetic variation and evolutionary potential; thus, gene flow is also important to conservation and management of these species. For example, the Reddish Egret (Egretta rufescens) has recovered after severe population reductions during the 19th and 20th centuries, but population numbers remain below historical levels. In this study, we characterized gene flow among management units of the Reddish Egret by using ten nuclear microsatellite markers and part of the mitochondrial (mtDNA) control region from 176 nestlings captured at eight localities in Mexico (Baja California, Chiapas, Tamaulipas, and Yucatan), the USA (Texas, Louisiana, and Florida), and the Bahamas. We found evidence of population structure and that males disperse more often and across longer distances compared with females, which is congruent with previous banding and telemetry data. The maternally inherited mtDNA and biparentally inherited microsatellite data supported slightly different MU models; however, when interpreted together, a four MU model that considered population structure and geographic proximity was most optimal. Namely, MU 1 (Baja California); MU 2 (Chiapas); MU 3 (Yucatan, Tamaulipas, Texas, and Louisiana); and MU 4 (Florida and the Bahamas). Regions outside our sampled localities (e.g., the Greater Antilles and South America) require additional sampling to fully understand gene flow and movement of individuals across the species’ entire range. However, the four MUs we have defined group nesting localities into genetically similar subpopulations, which can guide future management plans.     

颍上八里河自然保护区鹭卵3种重金属残留分析

2005年5月,采集了淮河地区颍上八里河集群繁殖的夜鹭(Nycticorax nycticorax)和小白鹭(Egrettagarzetta)鸟卵共18枚,用原子吸收法测定了卵壳、内容物中重金属Cd、Pb、Cr的残留量。结果表明,所有卵壳样品中均检出一定水平的Cd、Pb和Cr残留量,夜鹭卵壳中重金属残留量为Pb>Cr>Cd,小白鹭卵壳中重金属残留量为Cr>Pb>Cd,卵壳中Pb和Cr残留量的种间差异都不显著,但Cd的种间差异显著;在2种鹭卵内容物中,Cr都被检出,在夜鹭卵内容物样品中,Pb只被部分检出,Cd在2种鹭卵内容物样品中都没有被检出,3种重金属在内容物中残留量的种间差异都不显著。2种鹭卵壳中Pb和Cd残留量极其显著地高于卵内容物,但Cr的这种残留分布上的差异不显著。本研究进一步证明卵壳可用作重金属污染物的指示物,监测和评价湿地生态系统中重金属的污染状况。     

颍上八里河自然保护区鹭卵p3种重金属残留分析

2005年5月,采集了淮河地区颍上八里河集群繁殖的夜鹭（Nycticorax nycticorax）和小白鹭（Egretta garzetta）鸟卵共18枚,用原子吸收法测定了卵壳、内容物中重金属Cd、Pb、Cr的残留量。结果表明,所有卵壳样品中均检出一定水平的Cd、Pb和Cr残留量,夜鹭卵壳中重金属残留量为Pb〉Cr〉Cd,小白鹭卵壳中重金属残留量为Cr〉Pb〉Cd,卵壳中Pb和Cr残留量的种间差异都不显著,但Cd的种间差异显著;在2种鹭卵内容物中,Cr都被检出,在夜鹭卵内容物样品中,Pb只被部分检出,Cd在2种鹭卵内容物样品中都没有被检出,3种重金属在内容物中残留量的种间差异都不显著。2种鹭卵壳中Pb和Cd残留量极其显著地高于卵内容物,但Cr的这种残留分布上的差异不显著。本研究进一步证明卵壳可用作重金属污染物的指示物,监测和评价湿地生态系统中重金属的污染状况。     

不同鸟类生境网络复合与优化——以苏锡常地区白鹭、鸳鸯、雉鸡为例

通过复合优化不同焦点物种的生境网络表征多数物种生境网络实现物种多样性保护,具有重要理论价值和实践意义。以苏锡常地区为研究区域,以白鹭、鸳鸯和雉鸡3种鸟类为焦点物种,通过采用生境斑块约束条件模型与最小成本路径法相结合的方法识别出生境网络;从满足集合覆盖问题视角出发,通过采用网络构成要素复合的方法进行网络复合,其中廊道与廊道的复合通过采用评价生态系统服务价值的方法实现;通过采用观测数据为生境斑块和迁移廊道增补依据的方法进行复合生境网络优化。结果表明:生境网络经过复合,廊道总面积、总长度及生态系统服务价值在分别减少了16%、68%和10%的情况下,保持了斑块间的连接度、兼顾到经济效益和生态效益最大化、覆盖了占总数86%以上的75处观测点;复合生境网络经过优化,覆盖了2010年及以后所有84处观测点,廊道总面积、总长度及生态系统服务价值分别增加了19%、21%和27%;说明生境网络复合优化定量分析方法和思路具有可行性,为网络复合研究提供了借鉴。     

PERMANENT GENETIC RESOURCES: A set of primer pairs for amplifying the complete mitochondrial DNA of endangered Chinese egret (Aves, Ardeidae, Egretta eulophotes)

The Chinese egret is a globally endangered species. Here we describe a set of primer pairs to amplify its entire mtDNA. The polymerase chain reaction products (1000–2000 bp) were successfully amplified by using this primer set and were then sequenced and aligned. The contiguous mtDNA sequences of the Chinese egret were assembled to be a circular molecule (17 579 bp). This primer set was also confirmed to be useful for six other species of ardeid birds. The versatility of this primer set will provide a groundwork for further studies on the genetic structure and molecular evolution of the ardeid species.     

四种鹭类繁殖生态生物学研究

本文对夜鹭,白鹭,黄鹭白鹭,池鹭混群在同一巢区的繁殖,种间协高及雏鸟生长进行进行了观察研究,其中黄嘴白路豫南大别山类新纪录,在此繁殖亦为首次发现。几种路在巢位,食性,取食活动和习性方面都表现出其混居同一巢地繁殖的种间协调性,符合高期假说。比较４种鹭鸟雏鸟生长过程中各生长参数。其中池鹭虽个体最小,但体重和各部位生长却对较快。     

三种鹭异步孵化与雏鸟生长的比较研究

根据1996～1999年的野外工作和实验饲养,研究了池鹭、白鹭、夜鹭3种鹭的繁殖、雏鸟生长和异步孵化对雏鸟生长的影响.3种鹭于4月上、中旬迁到常山、余杭鹭保护区,9月下旬陆续迁离.孵卵期池鹭为23.0 d(n=26),白鹭23.9 d(n=32),夜鹭25.3 d(n=34);孵化率池鹭为76.32%,自鹭86.96%,夜鹭95.45%,池鹭繁殖力为3.21只,白鹭3.38只,夜鹭3.50只.雏鸟体重增长与成体体形大小呈负相关.幼雏体重增长与孵化顺序相关.在生长早期(≤8 d)全部雏鸟正常发育,之后差异显著.第1和第2孵化雏鸟生长曲线相似,但明显高于第4雏鸟,表明较早孵化者获得食物能力较强,而迟孵出雏鸟有食物不足现象.该3种鹭孵育幼雏能力的最适度估计为3只左右.     

白鹭作为无锡太湖地区环境污染指示生物的研究

2000年4—6月对分布在无锡太湖地区的4种要鸟中的白鹭(Egretta garzetta)行为生态学及其生境污染状况进行了调查研究．调查地白鹭主要栖息树种包括马尾松(Pnus masson±ana)、香樟树(C±nnamomum hupehanum)、麻砾树(Quercus acut±ssema)、榆树(Ulmus prm±la)和杨梅树（Myr±ca rubra)．栖息地总面积为7hm^2,白鹭总巢数为4200个,每棵树平均0．38个．白鹭的孵化期为19—21d,卵重23．9±4．0g(n=41),平均卵大小(44．5±4．1)mm×(32．6±4．9)mm(n＝41),平均窝卵数5．02(2—8)枚,平均窝雏数3．86(2—7)只,孵化成功率为84．25％．对白鹭雏鸟左右跗Zhe的测量分析表明不对称性不显著(P>0．05)．白鹭雏鸟食物较小,繁殖期间主要以小型鱼类和虾类为食．污染物分析结果表明,白鹭卵中除例外,六氯苯、六六六、环二烯类、DDTs、DDE、PCBs、Cr、Hg和Pb均检测到．食物链(底泥-食物-白鹭雏鸟)中,有机杀虫剂和重金属都逐级富集．通过与相对无污染的鄱阳湖地区比较,太湖地区和鄱阳湖地区卵样品中的DDs(包括DDT、DDE和DDD)浓度最高(超过2μg·g^1),其它污染物浓度均较小．太湖地区白鹭卵中的DDTs、Cd和Cr浓度低于鄱阳湖地区,其它污染物浓度鄱阳湖地区均低于太湖地区．经比较分析,两地样品中有机氯杀虫剂、PCBs和各种重金属浓度都未达到影响白鹭繁殖成功率的阈值．