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1.
In Israel, a well-known avian migratory bottleneck, there is a temporal and geophysical divide in the flyways. The migration at Eilat, at the southern tip of Israel, is disjunct from the flyway in central and northern Israel. In order to elucidate the differences between the two flyways, we compared the data collected simultaneously at the Kfar Ruppin ringing station in northern Israel, and in the IBRCE Bird Sanctuary in Eilat at the southern tip of Israel. We chose the three most common species that are typical long distance, trans-Saharan, passerine migrants: Blackcap (Sylvia atricapilla), Lesser Whitethroat (Sylvia curruca) and Reed Warbler (Acrocephalus scirpaceus). At both ringing stations, the number of migrants recorded in spring was considerably greater than in autumn for all three species. Individuals from all species analysed in both passage seasons at Kfar Ruppin had longer wings than in Eilat, and in spring all three species were heavier in Kfar Ruppin. Our study is the first to show that there are biometric differences within Israel and stress the need to study the eastern migratory flyway of the Western Palaearctic in order to fully understand the intercontinental movements of the EurAsian migratory passerine populations.  相似文献   

2.
In combination with observations in spring staging and wintering grounds in western Europe, a detailed etho-ecological study of nesting dark-bellied brent geese Branta b. bernicla in western Taimyr, Krasnoyarsk, Russia, was made in 1990. Most brent geese arrived on the breeding grounds from 14–19 June and started nesting within a few days. In the study area 264 nests of breeding brent geese were found, mainly on islands but also along small rivers on the mainland. The mean clutch size was 3.0 and 80% of the eggs hatched. Time budget studies showed that incubating females spent on average 138 minutes per 24 hours on feeding. Despite favourable weather conditions and a low density of arctic foxes, only about one-third of the mature birds in the study area bred. In the autumn an intermediate breeding success of 20% juveniles was recorded in the wintering areas. This was probably due to the relatively poor condition in which the brent geese left their spring staging areas.  相似文献   

3.
Factors influencing avian abundance and diversity in central Saudi Arabia were investigated over a 28-month period using walked belt transects in five local habitat types in a 2200 km2fenced desert protected area established in 1989. Enclosure of the protected area has resulted in the development of a mosaic of densely vegetated grassland and savanna areas amongst the sand and gravel plains which dominate the surrounding landscape. Overall bird diversity showed biannual peaks corresponding to spring and autumn passage migration, when 30–40 species were recorded; troughs occurred in summer or winter (9–12 species) following poor spring or autumn rains. Bird numbers responded dramatically to heavy rainfall (> 20 mm in a month) occurring two months earlier, with major peaks recorded in autumn 1992 and May–June 1994. Numbers of granivorous species, principally larks, fluctuated mostly in relation to rainfall, whereas largely insectivorous species tended to remain more stable. A desert locust plague in spring/summer 1993, combined with poor spring rains, resulted in the lowest numbers and species diversity recorded during the study.  相似文献   

4.
乌梁素海是干旱半干旱地区典型的湿地。其位于东亚—澳大利西亚及中亚—印度两条迁徙路线上,是迁徙候鸟极其重要的繁殖地和停歇地。从2009到2012年,我们采用样线法和样点法对水鸟及其栖息地进行调查,共记录了98种水鸟,隶属于6目、14科,同时记录到水鸟个体超过100 000个。其中夏候鸟55种(在此繁殖)、旅鸟39种(在此短暂停留),分别占所记录物种数的56.12%和39.80%。对所记录的鸟类及其种群的迁徙规律进行进一步分析,结果表明:春季迁徙期主要为3月上旬到5月中旬,比秋季迁徙期(8月上旬到11月中旬)短。水鸟繁殖的高峰期是4月上旬到5月下旬。重点保护水鸟(包括IUCN红色名录中的受胁物种以及中国重点保护野生动物名录中的Ⅰ、Ⅱ级保护物种)的集中分布时间是4月上旬到5月下旬以及9月上旬到11月上旬;相比春秋迁徙季节,夏季水鸟的群落结构相对稳定。基于研究,我们建议将乌梁素海湿地列入国际重要湿地名录及迁徙路线网络。此外,栖息地管理对鸟类分布的决定作用同样在文中加以讨论。  相似文献   

5.
We provide a test of the hypothesis that most Palaearctic-African migratory passerines breeding to the east of Eastern Europe avoid crossing western deserts of Central Asia during autumn migration and make a detour through the steppes and semi-deserts north of the Caspian Sea. Trapping data at a migratory stopover and moon-watch observations in September 2003 in western Kazakhstan in a semi-desert location 375 km north of the Caspian Sea support this hypothesis.  相似文献   

6.
河西走廊地势狭长,位于两山之间,主要由荒漠构成,生境一旦遭到破坏,当地物种将很难找到替代的栖息地。本文以河西走廊中部典型砾质戈壁为研究区,经由2019—2020年红外相机和人工观测等方式监测到的兽类和鸟类数据为基准,探讨其群落动态及活动节律。结果表明:砾质戈壁兽类中的国家Ⅱ级重点保护及“三有”(有重要生态、科学、社会价值)动物有6种,而砾质戈壁鸟类中的国家Ⅱ级重点保护及“三有”动物有8种。兽类群落的季节变化小,春季鹅喉羚(Gazella subgutturosa)等的相对多度指数略高于其他季节,三趾跳鼠(Dipus sagitta)在4月大量出现;鸟类群落季节变化明显,春、夏季和秋季鸟类的相对多度指数高于冬季,物种数在夏季和秋季达到峰值。兽类和鸟类的相对多度变化趋势相似,均在夏末和春季达到顶峰。兽类的月相对多度指数与土壤含水量呈极显著的负相关,鹅喉羚和沙狐(Vulpes corsac)等日活动节律受人类活动影响出现在夜间、黄昏或黎明。鸟类的月相对多度指数与人类活动、空气温度、土壤温度和节肢动物均呈显著正相关,但人类活动在生长季会降低一些鸟类的活动频率。总之,河西走廊中部戈壁是鹅喉羚、沙狐、红隼(Falco tinnunculus)、锲尾伯劳(Lanius sphenocercus)、黑尾地鸦(Podoces hendersoni)、沙鵖(Oenanthe isabellina)、漠鵖(Oenanthe deserti)和短趾百灵(Calandrella cheleensis)等兽类和鸟类的主要栖息地,建立沙化土地封禁保护区对保护荒漠动物多样性具有重要的生态意义。  相似文献   

7.
Herbivorous tortoises in arid, winter-rainfall regions need to forage in seasons that provide relatively little heat for their ectothermic metabolism. To help understand how tortoises exploit resources in winter-rainfall areas, I recorded ambient, soil, and body temperatures for Homopus signatus in four spring seasons, and in one summer, autumn, and winter. The spring thermal environment enabled H. signatus to maintain body temperatures that were high compared to other small tortoise species. Mature females had higher spring body temperatures than males and immature individuals, probably because mature females were developing eggs. In summer, autumn, and winter, body temperatures differed between males and females, relating to sexually different activities and retreat uses. The relatively high body temperatures of H. signatus in winter and spring, along with a non-isometric relationship between body temperature and soil temperature, suggest that tortoises thermoregulated and may need considerable time to gain heat. Additional studies should compare body temperatures of H. signatus to operative temperatures, and determine the vulnerability of the taxon to human interferences that affect behavioural time budgets and body temperatures.  相似文献   

8.
位于长江口的崇明东滩是东亚一澳大利西亚候鸟迁飞路线上一个重要的候鸟迁徙停歇地。保护区的环志工作始于1986年,自2002年,每年春季和秋季都进行较系统的环志工作。至2010年底,已环志鸺鹬类46种36800余只,其中超过95%的鸟佩带了代表长江口地区标识的黑白色足旗。其中大滨鹬、黑腹滨鹬和翘嘴鹬是崇明东滩环志数量最多的3种鸟类,环志数量分别为10631、3056和2746只。为了便于野外个体识别,保护区于2006年起在环志时尝试使用编码足旗,到2010年,共有9种1758只鸟佩戴了编码足旗。在环志过程中,总计有20种441只来自不同国家地区的环志鸟被回收。回收鸟中超过一半的鸟为大滨鹬,而且70%的回收鸟是在西北澳洲被环志的,表明崇明东滩与西北澳洲对于迁徙涉禽的保护上有非常紧密的联系。崇明东滩环志研究所获得的数据对于了解东亚一澳大利西亚迂徙涉禽的迂徙研究提供了宝贵资料。  相似文献   

9.
上海世博园后滩湿地大型底栖动物群落特征与环境分析   总被引:1,自引:0,他引:1  
上海世博园后滩湿地是中国2010年上海世界博览会规划区的重点建设项目。对世博园后滩湿地潮间带底栖动物群落特征与生物多样性进行了春、夏、秋、冬4个季节的调查研究,并对该湿地水体污染状况及影响底栖动物分布的因素进行分析与评估。结果表明:世博园后滩湿地底栖动物主要由环节动物、软体动物、节肢动物与纽形动物组成,共计18种;物种数在夏季最丰富,春季次之,冬季物种数最少,其中A断面物种数大于B断面;群落生活类群面上生活类群(GS)/面下生活类群(GSB)在冬季最大,春季次之,秋季群落生活类群GS/GSB最小,其中B断面群落生活类群GS/GSB大于A断面;底栖动物群落的Margalef物种丰富度指数(d)在夏季最大,春季次之,冬季丰富度指数最小;Shannon-Wiener指数(H′)在夏季最大,春季次之,秋季最小;Pielou均匀度指数(J)为:冬季最大,夏季次之,秋季最小;Simpson优势度指数(D)为:秋季最大,春季次之,夏季最小;采用寡毛生物指数值和生物多样性指数对该湿地水体污染状况进行了评价,该园区水质污染程度为中度污染。  相似文献   

10.
Shrub is an important factor on structuring ground arthropod communities in desert ecosystems. In this study, in order to determine how shrubs and their species influence ground arthropod distribution patterns in a sandy desert scrubland dominated by two different shrub species, Calligonum mongolicum and Nitraria sphaerocarpa, the ground arthropods were sampled with pitfall traps during spring, summer and autumn. At the community level, total arthropod abundance was shown to be significantly higher under shrubs than in intershrub bare areas in spring; similar patterns occurred in terms of the richness of arthropod groups in the spring and over three seasons, suggesting season-specific shrub presence effects on arthropod activity. In addition, more arthropods were found under N. sphaerocarpa shrubs than under C. rnongolicum shrubs in autumn, suggesting season-specific effects of shrub species of arthropod activity, whereas more arthropods taxa were captured under C. mongoIicum than N. sphaerocarpa. At the trophic group level, the abundances of predator and herbivore arthropods were significantly greater under shrubs than in intershrub bare habitats, whereas herbivore arthropods were more abundant under N. sphaerocarpa than C. rnongolicum, and an opposite rule was detected for predator arthropods At the family level, the mean abundances of Carabidae, Curculionidae, Gnaphosidae and Lycosidae were significantly higher in the shrub microhabitats than in the intershrub bare habitat, there was no significant difference between habitats on the mean abundances of Formicidae and Tenebrionidae. The study results suggested that shrub presence and shrub species variation are important determinants of ground arthropod assemblages in this desert ecosystem, but the responses of ar- thropods differed among trophic and taxonomic groups.  相似文献   

11.
Assemblages of small bird species (<90 g body mass) from the Monte desert in Argentina were studied to analyze spatial and temporal variation in abundance and species richness. Mean species richness was higher during breeding season than in non-breeding season. The same pattern was observed in aerial insectivores, while granivores and substrate insectivores did not differ between breeding and non-breeding seasons. Overall bird abundance was similar across seasons. Species richness was positively correlated with bird abundance and negatively correlated with dominance; bird abundance and dominance were not correlated. These patterns could be explained by distinct responses of functional groups of birds; dominant species were granivores in the non-breeding season and aerial insectivores during the breeding season, and bird abundance in functional groups changed according to food supply. Most species are residents or regular migrants, while there are few nomadic and transient species. Predictable annual fluctuations in rainfall and resource availability should favor a migratory strategy more than nomadic movements. Similarly, breeding is strongly seasonal and most species start breeding when the first summer rains have generally not yet fallen. Finally, concordances in assemblage structure at local and regional scale suggest that similar mechanisms are acting on the local bird assemblages across the Monte.  相似文献   

12.
库姆塔格沙漠大尺度风场特征分析   总被引:4,自引:4,他引:0  
利用美国NCEP/NCAR1979—2006年27 a地面10 m高度的日平均风场再分析-2资料以及46 a的地面常规气象站观测资料和1 a的沙漠中自动气象站观测资料,对库姆塔格沙漠地区风场进行了统计与诊断分析。结果表明:沙漠地区,一年四季北风和东北风为近地面主要存在的风向,春季风速最强,夏季次之,秋冬季最弱;在夏秋冬季节,由于北风的逐渐减弱,加上受到南侧阿尔金山和青藏高原风场的影响,南下的气流在沙漠南侧分为三支,分别流入新疆、青海和甘肃。春夏季节在沙漠北侧基本都是以东北风或者西北风吹向库姆塔格沙漠,秋冬季节,沙漠地区出现西南风。根据沙漠周围6个气象站风场风速显示,库姆塔格沙漠地区风速存在明显的周期变化,在过去的10多年中库姆塔格沙漠周围风场风速处于一个低谷期,但最近几年风速有不断加强的趋势。  相似文献   

13.
塔克拉玛干沙漠辐射平衡研究   总被引:3,自引:0,他引:3  
本文对塔里拉玛干沙漠辐射平衡实测值与计算值进行了对比,分析了辐射平衡不同季节的日变化及年变化特征,并分析了影响辐射平衡的各主要因子,得到了沙漠辐射平衡研究的一些新认识。  相似文献   

14.
In arid environments, limited resources may compromise allocations to reproduction, while unpredictable rainfall may confound the timing of reproductive events. Here we evaluate how female tent tortoises (Psammobates tentorius tentorius) allocate resources to reproduction while coping with low and unpredictable rainfall. Vitellogenesis in tent tortoises started in autumn, when rainfall was highest and most predictable. Tent tortoises required a high body condition and large follicles to ovulate their first clutches, but a temperature threshold for ovulation may have prevented breeding during the winter months. Females produced small clutches (1.78±0.63; 1–3 eggs) but produced several clutches (3.7±1.6; 1–6 clutches) from spring to late autumn. Clutch frequency (CF) was correlated to body condition, and CF rather than clutch size (CS) determined annual fecundity. Although body size influenced egg size, body size had no effect on CS, CF or fecundity. There was no trade-off between relative egg size and CS. The small clutches of tent tortoises limit the risks of producing too many offspring at one time, a scenario that may leave females without resources for their own needs. When clutches are small, an extended breeding season enhances reproductive output by providing females more time and opportunities to leave offspring.  相似文献   

15.
ABSTRACT

Migratory birds have evolved diverse migration strategies in response to a variety of factors, but information about the detailed migration patterns of Asian songbirds is not yet available. To understand the short-distance migration pattern of declining Yellow-throated Buntings (Emberiza elegans) in East Asia, we analyzed stable isotopes from the outermost tail feathers (rectrices) of individual buntings collected in Korea and Japan. Temporal changes in feather hydrogen (δ2Hf) and oxygen (δ18Of) isotopic values at stopover islands suggested that northern populations start migration earlier than southern populations, especially in autumn. Latitudinal gradient in δ2Hf values of three wintering populations implied that northern breeders wintered farther north than southern breeders. The migration pattern of this bunting, known as Type II chain migration, was also inferred from hydrogen isotope-based geographic assignments of feather growth origins. Our data demonstrate that stable isotope analysis may help to bridge current knowledge gaps in songbird migration despite coarsely mapped isoscapes and as-of-yet undetermined isotope calibration functions in Asia.  相似文献   

16.
Esophageally fistulated goats were released in a microphyll desert scrub habitat with 14.6% or 46.2% aerial cover of Atriplex canescens (induced by removal of all shrubs except A. canescens, with livestock grazing exclusion for 10 years) to determine the seasonal forage species selected by the goats. The shrub removal strongly influenced the goats’ feeding habits. The goats grazing the Atriplex-dominated site consumed 4.5 times more A. canescens than the goats on the untreated (control) pasture during all seasons. Shrubs were used heavily during all seasons by goats in both pastures, with higher percentages (75.5–82.8%) in the diets of goats grazing the control pasture than in the diets of goats grazing the Atriplex-dominated area (62.5–68.5%). No differences were found between seasons. The goats in the Atriplex-dominated pasture ate more grass than the goats grazing the control area and used more perennial graminoids during the summer (15.0%) and spring (18.3%) than the goats on the control area (6.0–7.0%). Forbs were an important component of diets. It was concluded that the successful revegetation of the treated pasture affected the goats’ feeding strategy, with an increase in the use of A. canescens, forbs and grasses in all seasons.  相似文献   

17.
张喆  丁建丽  王瑾杰 《地理学报》2017,72(3):507-520
中亚地处干旱和半干旱气候区,是全球沙尘气溶胶贡献度较大的区域。利用中分辨率成像光谱仪(Moderate-resolution Imaging Spectrometer, MODIS)和云—气溶胶偏振雷达(Cloud-Aerosol Lidar with Orthogonal Polarization, CALIOP)遥感数据,从宏观角度对2002-2015年中亚地区气溶胶光学厚度(Aerosol Optical Depth, AOD)时空分布特征及沙尘气溶胶光学特性垂直分布特征进行分析,利用拉格朗日混合型的扩散模型(Hybrid Single Particle Lagrangian Integrated Trajectory, HYSPLIT)讨论沙尘运输的季节性变化。结果表明:① 中亚AOD空间分布呈现显著的季节性差异,四季均值春(0.412)>夏(0.258)>冬(0.167)>秋(0.159),14年间呈现增加趋势;② 中亚AOD高值区域主要集中于咸海地区和新疆的塔里木盆地,其中,咸海地区AOD年均值为0.278,年均增幅为3.175%,主要受咸海退化所导致的干涸湖底裸露面积加大的影响;塔克拉玛干沙漠地区AOD年均值为0.421,年均增幅0.062%,主要受温度和风速两方面的影响,不同季节下主导因素略有差异;③ 尘源区气溶胶主要集中在近地面0~2 km范围内,沙漠上空气溶胶退偏比范围(10%~45%)略大于咸海上空(15%~30%);咸海地区色比值(0.3~0.8)小于沙漠地区(0.5~0.9),且在0~2 km和4~6 km有两个高频色比值分别为0.5和0.3,说明相比沙尘气溶胶,咸海地区的盐尘气溶胶球形程度较高,颗粒更小,飘散高度更高;④ 咸海地区盐尘潜在扩散方向主要以东北,西南和南为主,向东北方向的扩散距离最远,影响范围可达俄罗斯中部地区,西南方向扩散路径高度和距离较近,主要影响乌兹别克斯坦和土库曼斯坦,但发生比例相对较高,塔克拉玛干沙漠地区起尘后大部分沙尘颗粒仍沉降在尘源区附近,向东部地区扩散的沙尘气溶胶,主要影响中国青海、甘肃、宁夏、陕西等地区。  相似文献   

18.
塔克拉玛干沙漠地表潜热时空特征分析   总被引:6,自引:4,他引:2  
利用1979年3月至2004年2月月平均的NCEP/DOE再分析地表潜热资料,在分析塔克拉玛干沙漠四季潜热基本气候特征的基础上,通过EOF方法,对沙漠地表潜热异常变化的空间结构和时间演变趋势作了诊断研究。结果表明:①沙漠地区夏季潜热最大,春季和秋季次之,冬季最小;靠近山区的沙漠西部、西北部地区四季明显大于中、东部地区。②根据四季地表潜热距平场的EOF分析,该区潜热异常主要有全区一致型、南北差异型以及西北—东南差异型三种常见的分布模态。③25 a期间,塔克拉玛干沙漠地表潜热在第一空间尺度上四季都有不同程度增强的趋势;在第二空间尺度上,春季沙漠北部、西北部有减弱的趋势,南部、东南部有增强的趋势,而冬、夏、秋季变化趋势不是很大。  相似文献   

19.
灵丘黑鹳生境的保护与管理   总被引:1,自引:0,他引:1  
山西省灵丘县具有很好的黑鹃生存环境,征我凼不仪是黑鹳主要的栖息、繁殖地,而且还是我国唯一的越冬地。分析了灵丘黑鹳的生活习性、生境成因,针对黑鹳牛境保护管理中存在的问题,提出了几点保护建议。  相似文献   

20.
季节变化对全球气候变化的响应——以湖北省为例   总被引:8,自引:0,他引:8  
陈正洪  史瑞琴  陈波 《地理科学》2009,29(6):911-916
根据湖北省10个代表站1951(或建站)~2006年逐日平均气温,计算分析了四季初日和长度及其变化趋势,以揭示气候季节对全球气候变暖的响应。结果表明:(1)湖北省平均春、夏、秋、冬四季初日分别为3月22日、5月27日、9月27日、11月27日,四季长度分别为65.7、122.8、60.9、115.6d,且时空差异明显;(2)56a来湖北省平均入春、入夏分别提前2.8、1.6d,入秋、入冬分别推后4.0、6.1d;(3)56a来湖北省平均冬季缩短8.9d,夏季延长6.3d,秋季延长2.0d,春季无变化;荆州夏季延长21.1d,武汉冬季缩短17.0d。  相似文献   

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