江西省中华秋沙鸭越冬种群现状调查与胁迫因素分析

于2009年2月对江西省五大水系:赣江、抚河、信江、饶河和修水的越冬中华秋沙鸭种群展开专项调查,分析了江西省越冬中华秋沙鸭种群的数量、性比、空间分布格局、生境特征及其胁迫因素.主要采用样线法在五大水系的主要河道展开同步调查,调查样线总长度400 km.结果发现,江西省越冬中华秋沙鸭有26个生活群255只个体,雌雄性比为119:117,其生活群雌雄性比也多接近1:1.江西省五大水系中,除赣江外,在其他4个水系均发现有中华秋沙鸭越冬群体.除了在曾有中华秋沙鸭越冬记录的婺源、贵溪、弋阳、浮梁、修水发现其越冬群体外,还首次在江西省境内的宜黄、武宁和龙虎山地区发现有较大的中华秋沙鸭越冬群体,而且龙虎山泸溪河段分布有本次调查中个体数量最大的有53只个体的群体.人类采砂活动、水质污染、非法捕鱼和家禽饲养是目前影响该种群生存的主要胁迫因素.     

藏原羚集群行为的初步研究

2002年10月至2003年12月,在可可西里对藏原羚(Procapra picticaudata)的集群行为进行了初步研究.将其集群划分为雌性群、雄性群、母仔群、雌雄混群和独羚5种类型.共统计藏原羚924群次,计3643只次.其中,雌性群525群次,占56.8%,为最多的集群类型;其余为独羚(26.1%)、雄性群(11.0%)、母仔群(3.0%)和雌雄混群(3.0%).不同大小集群的比例亦有极显著差异,其中2-10只的集群占70.0%,独羚占26.1%,其余为3.9%;最大集群为17只.另外,选择2-8只的集群的个体数占72.9%,选择8只以上集群的个体数为20.5%,独羚仅占6.6%,选择不同大小集群的个体数的差异也极为显著(P<0.001).除独羚外,其余4种集群类型的集群大小存在极显著差异.独羚作为一种特殊的集群类型,其雄性个体的比例占到68.1%,这说明雄性个体比雌性更容易形成独羚.总体而言,藏原羚的集群以雌性群为主,最适集群大小为2-8只.     

天目溪中华秋沙鸭生态习性研究

中华秋沙鸭Mergus squamatus是全球濒危物种。2015—2018年在浙江省杭州市临安区天目溪开展了该物种越冬种群的监测研究。调查累计发现25群中华秋沙鸭,计106只次,平均每群4. 24只±0. 98只,性比为1∶3. 82,主要集成3～6只/群,分为3个类群,即孤雌群、雌性群和混和群。中华秋沙鸭主要栖息于开阔的河道,河宽30～60 m,附近有沙洲;水体较浅,水深40～60 cm;水流平缓,水流速度为0. 3～0. 5 m·s~(-1)。中华秋沙鸭对人为活动十分敏感,其栖息地远离居民点,距公路的距离可至30 m以内,但这种生境需要茂密的乔灌木或竹林隔离。     

贺兰山岩羊种群结构的季节性变化

2001年3月至2002年2月,每月定期在固定的样线上,采用样线法对贺兰山3929只岩羊种群结构进行调查。小群体是贺兰山岩羊种群的基本特征,全年群平均数为5．5只,独羊全年存在,以雄性成体为主,在雌性群中,母仔群全年稳定,占雌性群的44．0％。岩羊雌性群群体大小平均3．5只,雄性群群体平均4．5只,混合群群体平均8．0只;全年雌性多于雄性,雌性群小于雄性群。群体表现为雌性群群体小,群体数量多;混合群体大,群体数量少。混合群群体大小范围离散,雄性群次之,雌性群群体范围变化最小。全年雌幼比为100：48。雌雄性比全年100：71,其中,2～6月份,雌雄性比为100：130～155;7—12月份,雌雄性比为100：43．68。另外,中还指出3．5～8．5龄雄羊占63．9％,1．5～3．5龄和超过8．5龄老年雄性岩羊所占的百分率明显较少。     

贺兰山岩羊（Pseudois nayaur）集群特征的季节变化

2004年11月～2005年10月,在贺兰山对岩羊(Pseudois nayaur)的集群行为进行了研究,将其集群类型划分为雌性群、雄性群、雌雄群、母仔群、混合群和独羊6种类型.共观察到岩羊1 023群次,计4 866只次,平均群大小为(4.86±2.54)只,最大的群为51只,最小的为独羊.其中,母仔群459群(44.87%)为最多的集群类型,其余为混合群(20.72%)、雄性群(14.86%)、独羊(9.09%)、雌雄群(5.57%)、雌性群(4.89%).母仔群出现的频次在4个季节均最高,除母仔群外,春季雄性群出现的频次最高,而夏、秋、冬季都是混合群出现的频次最高,不同类型集群出现频次的季节间差异极显著.在4个季节中都以2～5只的群居多,其出现的频次占各季节群数50%以上,不同季节群大小差异极显著,而不同集群类型群大小季节间不存在显著差异.除独羊外,不同季节混合群大小差异极显著,母仔群、雌性群大小差异显著,而雄性群、雌雄群大小无显著差异.研究结果显示,贺兰山岩羊集小群是其显著特点,随着季节的变化,其集群类型、集群大小均会发生一定的变化.     

天山盘羊集群行为的研究

除了孤盘羊外,盘羊集群可分为４类,即雌性群,雄性群、混合群和家庭群。雌性群和雄性群是盘羊的基本群。其余为季节性群。根据３－１１月野外１８２群,２０４０只盘羊统计。盘羊全年群平均１１．２（２－５６）只,雌性群１２．８（２－５６）只,雄性群６．６（２－１６）只和混合群１８．１（６－４３）只。同时对盘羊群体的季节性变动进行了研究。盘羊集群与其自身的生物学特性、环境的水热分布和人类的竞争有关,因此不同地区     

中华秋沙鸭在中国的近期越冬分布与数量

中华秋沙鸭(Mergus squamatus)以往在我国广有越冬记录,但分布点零散,且多为小群或零星个体,很少在同一地点见到10只以上的个体记录。20世纪90年代以来在个别地点虽发现有中华秋沙鸭的越冬群体,但缺少持续性观察结果。21世纪初在赣东北的弋阳、婺源相继发现中华秋沙鸭的较大越冬群,总数量至少超过100只,且数量和分布地点相对保持稳定。两地记录到的最大数量分别超过该种全球总量的1%,应当加强保护。     

可可西里地区藏羚的社群特征

藏羚(Pantholopshodgsoni)的集群类型有雌性群、雄性群、母仔群、雌雄混群和独羚5种形式。2002年7月～2003年12月,在可可西里地区沿青藏公路设立试验区,直接观察到936群次,计13795只次藏羚。藏羚的集群类型受到生育周期的影响,季节间差异显著。春季以雌性群(60.49%)和雄性群(30.86%)为主;夏季和秋季主要为雌性群(41.65%,49.66%)和母仔群(49.36%,33.67%);雌雄混群(58.14%)主要出现在冬季。雄性群在1年中很少见,尤其是夏秋两季,冬季较为常见,多由亚成体雄性组成。独羚是一种特殊的集群类型,占11.32%。常见的集群大小为2～20只,占71.90%,其次是21～200只的群,占16.35%;>200只的集群极少,仅占0.43%,且仅出现于夏季产羔往返迁徙途中。藏羚的集群大小受竞争、捕食风险以及迁徙繁殖的共同影响。藏羚的集群极不稳定,交配期雌雄混合群受雄性亚成体的干扰经常改变,而在迁徙季节大群和小群之间的转换也很频繁。大型集群为雌性群或母仔群,其最适集群大小为2～20只。     

四川羚牛繁殖期集群类型及海拔分布

为了探究繁殖期四川羚牛Budorcas taxicolor tibetana的集群特征,于2012年7月在四川唐家河国家级自然保护区开展了羚牛集群类型与海拔分布的研究。在唐家河的8条监测样线(总长度约68.2 km)上记录到39群469头次,其中完整辨别群结构的有36群448头次。群体可定义为独牛、家群、混合群、社群和公牛群,研究期间大部分集群(83.33%)的个体数≤20。除独牛和公牛群外,群体平均大小为(14.70±2.63)头,各类型集群大小差异显著(F2,27=8.463,P=0.001)。独牛、家群、混合群和社群的记录海拔之间存在显著的差异(F3,31=11.8488,P<0.001),除公牛群外羚牛集群的平均海拔为(2015.37±89.74)m。羚牛集群记录的海拔与集群大小之间存在显著的线性相关(y=29.76x+1465,R2=0.802,P<0.001)。研究认为,繁殖期集群类型的变化与繁殖活动密切相关,聚集群和独牛是繁殖期雄性成体不同繁殖策略的体现。     

王朗国家级自然保护区岩羊集群结构及季节变化

岩羊（Pseudois nayaur）是青藏高原常见的食草动物,但对边缘分布区的种群了解较少。2018年6月到2019年8月,我们利用红外相机在四川王朗国家级自然保护区对岩羊的集群结构、特征及其季节变化进行了描述与分析。结果显示：调查共记录到岩羊1 921群次,共计6 623只次。按照性别和年龄组,可将岩羊集群划分为混合群、母仔群、雄性群、独雄、独雌、雌性群。研究观察到的最大岩羊集群为23只,最小为独羊（独雄或独雌）,集群的平均个体数量为（3.45 ± 2.16）只,以小群为主,种群大小的季节间差异不显著。岩羊集群结构和季节波动特征主要有：（1）混合群最常见,占45.3%,其次依次为母仔群、雄性群、独雄、独雌和雌性群;（2）岩羊集群结构季节波动显著,春季以雄性群（29.5%）和独雄（22.6%）为主,夏季、秋季和冬季主要为混合群（58.5%,41.8%,36.7%）和母仔群（21.4%,24.7%,18.6%）;（3）各集群类型在季节间的相对优势存在差异,例如混合群在夏季的优势显著,但母仔群在各季节的优势则无显著差异。依据全年数据,我们认为王朗国家级自然保护区的栖息地特征以及岩羊自身生命周期可能是影响岩羊集群大小、集群类型季节波动的主要因素。     

发情交配期贺兰山岩羊的集群特征

2003 年和2004 年的11 ～12 月,采用样线法和全事件取样法研究了贺兰山岩羊的集群特征。共观察到岩羊715 群,共计2 473只。发情前期平均群大小3.5±2.8 只(n = 241),发情期平均群大小3.4±3.2 只(n =297)。发情前期与发情期雄性群、雌性群、雌雄群、混合群及母子群大小间均无显著差异。发情前期到发情期群类型组成差异极显著,发情期雌雄群、混合群和独羊比例显著上升;雄性群、雌性群和母子群比例显著下降。发情前期到发情期,雄性岩羊在雄性群、雌雄群、混合群和独羊中的分布差异极显著,成年雌性岩羊在雌性群、雌雄群、混合群、母子群和独羊中的分布差异极显著。发情期4 个年龄等级雄性在雄性群、雌雄群、混合群和独羊中分布差异极显著,4 个年龄等级雄性岩羊都倾向分布于混合群。
     

Marine moult migration of the freshwater Scaly‐sided Merganser Mergus squamatus revealed by stable isotopes and geolocators

Scaly‐sided Mergansers Mergus squamatus breed on freshwater rivers in far eastern Russia, Korea and China, wintering in similar habitats in China and Korea, but nothing was known of their moulting habitat. To investigate the moult strategies of this species, we combined wing feather stable isotope ratios (males and females) with geolocator data (nesting females) to establish major habitat types (freshwater, brackish or saltwater) used by both sexes during wing moult. Although most Scaly‐sided Mergansers of both sexes probably moult on freshwater, some males and non‐breeding and failed breeding females appeared to undertake moult migration to brackish and marine waters. Given the previous lack of any surveys of coastal or estuarine waters for this species during the moult period, these findings suggest important survey needs for the effective conservation of the species during the flightless moult period.     

新疆天山中部北山羊社群结构

2013年10月至2014年9月,于天山中部天格尔山脉乌鲁木齐河源区研究了北山羊的社群结构。将其集群类型划分为雄性群、雌幼群、混合群和独羊4类。共统计北山羊497群,总计6 427只。北山羊最大集群为100只,最小群为1只,全年平均群大小为（12.93±0.65）只。其中春季（14.83±1.35）只,夏季（14.16±1.65）只,秋季（15.17±1.69）只,冬季（9.32±0.74）只。冬季北山羊平均集群大小显著低于其他三个季节。混合群的平均群大小最大,其余依次为雌幼群和雄性群。Kruskal-Wallis H检验结果表明各社群类型群大小差异极显著。北山羊多以2-7只的小群活动,占到总遇见频次比例的41.05%,8-20只群占32.80%,20只以上大群出现最少,占17.71%。在4种集群类型中,雌幼群出现频率最高,占51.91%,其次依次为混合群、雄性群和独羊。卡方检验结果表明4个季节间4种社群类型的出现频次差异显著。研究结果显示,北山羊在发情期混群,非繁殖期同性集群。受环境因素和自身生理周期的影响,其集群大小、集群类型均随季节变化而变化。     

Using Species Distribution Model to Estimate the Wintering Population Size of the Endangered Scaly-Sided Merganser in China

Scaly-sided Merganser is a globally endangered species restricted to eastern Asia. Estimating its population is difficult and considerable gap exists between populations at its breeding grounds and wintering sites. In this study, we built a species distribution model (SDM) using Maxent with presence-only data to predict the potential wintering habitat for Scaly-sided Merganser in China. Area under the receiver operating characteristic curve (AUC) method suggests high predictive power of the model (training and testing AUC were 0.97 and 0.96 respectively). The most significant environmental variables included annual mean temperature, mean temperature of coldest quarter, minimum temperature of coldest month and precipitation of driest quarter. Suitable conditions for Scaly-sided Merganser are predicted in the middle and lower reaches of the Yangtze River, especially in Jiangxi, Hunan and Hubei Provinces. The predicted suitable habitat embraces 6,984 km of river. Based on survey results from three consecutive winters (2010–2012) and previous studies, we estimated that the entire wintering population of Scaly-sided Merganser in China to be 3,561 ± 478 individuals, which is consistent with estimate in its breeding ground.     

Field evidence for bi-directional sex change in the polygynous gobiid fish Trimma okinawae

The social condition of bi-directional sex change in the gobiid fish Trimma okinawae was investigated at Akamizu Beach, Kagoshima, Japan. Social groups of T. okinawae usually consisted of a large male and one or more smaller females. The number of females in the group was positively correlated with male body size and groups were usually separated from each other by 1–3 m. In total, 22 instances of female-to-male sex change and three instances of male-to-female sex change were observed during the 16 months that social groups were monitored. Two individuals changed sex twice: female to male and back to female. Female-to-male sex change occurred when the male disappeared from a group. Either the largest remaining female changed sex to male or a large female from another group immigrated and changed sex to male. Larger individuals appear to benefit from becoming male because they can monopolize the breeding opportunities with several females, as reported in other protogynous fishes. Sex change from male-to-female only occurred when a solitary male joined another group as a subordinate. Mortality rates are high in these small fish, therefore joining another group and reproducing as a female is likely to increase the reproductive value of a solitary male.     

Some geometric aspects of house sparrow flocks

We analysed 50 movie films of house sparrows (Passer domesticus) foraging on an experimental grid. The location and orientation of each bird was recorded; sex of the individual was determined in about two of every three cases. Results revealed the following: (1) Flock size exhibited a weak inverse relationship to ambient temperature, though aggression was rare in the experimental patch. (2) The frequency of males in foraging groups exceeded the frequency of males in the local population. (3) Within a given flock size, nearest neighbour distances did not differ significantly between male-male and male-female pairs. However, average nearest neighbour distance was inversely related to flock size. (4) Solitaries oriented away from safety and toward a source of disturbance. Orientation of an individual within a larger group was more variable than that of a solitary, and the orientation of nearest neighbours indicated a significant tendency to keep each other in view.     

Status and distribution of golden langurs (Trachypithecus geei) in Assam, India

The distribution of golden langurs (Trachypithecus geei) is limited to a small area of western Assam in northeast India and Bhutan between the rivers Manas in the east, Sankosh in the west, and Brahmaputra in the south. It is one of the most seriously endangered primate species of India. A comparative analysis based on satellite images taken in 1988 and 1998 showed a 50% loss of original golden langur habitat. Data on population dynamics collected using line transect and total count methods are presented here. An average group size of 8.2 (range 4.0-22.0) individuals was recorded. A total of 1,064 individuals were counted living in 130 groups. The sex ratio was 1.9-2.5 adult females for each adult male. A low percentage of juveniles and infants suggests that the population is unstable. Most of the groups had only one adult male. Small group sizes, isolated distribution, proportionately few infants and juveniles, and degrading habitat are all causes of concern. Demographic trends indicate a decline in the golden langur population.     

Gravel Bars Can Be Critical for Biodiversity Conservation: A Case Study on Scaly-Sided Merganser in South China

Gravel bars are characteristic components of river landscapes and are increasingly recognized as key sites for many waterbirds, though detailed studies on the ecological function of gravel bars for waterbirds are rare. In this study, we surveyed the endangered Scaly-sided Merganser Mergus squamatus along a 40 km river section of Yuan River, in Central China, for three consecutive winters. We derived the landscape metrics of river gravel bars from geo-rectified fine resolution (0.6 m) aerial image data. We then built habitat suitability models (Generalized Linear Models—GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability. We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser. Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting. Therefore, maintaining the exposure of gravel bars in regulated rivers during the low water period in winter might be the key for the conservation of the endangered species. These findings have important implications for understanding behavioral evolution and distribution of the species and for delineating between habitats of different quality for conservation and management.