首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   31篇
  免费   3篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2019年   4篇
  2018年   4篇
  2017年   1篇
  2016年   6篇
  2015年   3篇
  2013年   6篇
  2009年   2篇
  2008年   2篇
  2006年   1篇
  2002年   1篇
  2001年   1篇
排序方式: 共有34条查询结果,搜索用时 15 毫秒
11.
The Egyptian Vulture Neophron percnopterus population in Morocco has undergone a marked decline since the 1980s to the point of nearing local extinction in the twenty-first century. A field study of some possible sites for Egyptian Vultures was carried out over six days during June 2014 in the Middle Atlas Mountains, Morocco. We counted a total of 48 Egyptian Vultures at three different localities: two occupied breeding sites and one communal roost that hosted 40 vultures of different ages. A (probable) singe adult bird at the breeding site was located and a previously occupied site was also visited. A preliminary survey amongst local people indicated that threats faced by this species are predator poisoning in some areas, and the use of vulture parts for traditional medicine. Given that the species is considered globally Endangered and populations continue to decline in many areas, the discovered population reported here, although relatively small, is of national and regional (North-west Africa) importance. We expect this new situation will revive the hopes for studying and conserving this and other vulture species in Morocco and North-west Africa in general.  相似文献   
12.
高山兀鹫(Gyps himalayensis)喜在山崖绝壁上营巢,海拔2 400~4 800 m的野外高空作业攀爬危险,观察难度较大。2014年4~9月,笔者在新疆天山中段尝试用国产遥控多旋翼微型飞行器寻找和拍摄高山兀鹫巢穴,结合路线搜索法和行为扫描法,进行栖息地调查、巢数统计、巢材分析,以及窝卵(雏)数、雏鸟生长与发育、繁殖周期、食性及食物分析。在7个地点的14个巢区的调查统计表明,高山兀鹫喜欢在朝南的崖壁上集群营巢(78.6%朝南,n=112),最长的一个繁殖地绵延7.3 km,距另外一个较近的巢区约47 km。巢材以禾草为主,如早熟禾(Poa spp.)、针茅(Stipa spp.)、老芒麦(Elymus sibiricus)等,缺乏粗大枝条。高山兀鹫1~2月产卵,窝卵数为1枚(n=21),整个繁殖周期长达8~9个月(1~10月份)。  相似文献   
13.
Upland buzzard (Buteo hemilasius), Saker falcon (Falco cherrug), and Himalayan vulture (Gyps himalayensis) are three common large raptors in the Sanjiangyuan National Park (SNP), China's first national park. Among them, Upland buzzard and Saker falcon play a significant role in controlling plateau rodent populations and reducing the transmission of pathogens carried by rodents. The Himalayan vulture can provide services for the redistribution and recycling of nutrients in the ecosystem, and play an irreplaceable role in the celestial burial culture of Tibetans in China. Exploring their habitat suitability is important for the protection of the three raptors. Our research was based on the current distribution of Upland buzzard, Saker falcon, and Himalayan vulture that we had extensively surveyed in the Sanjiangyuan National Park from 2016 to 2017. Combined with the correlation analysis of environmental variables, we utilized maximum entropy model (MaxEnt) to evaluate and compare the habitat suitability of the three species in the Sanjiangyuan National Park. Elevation, climate, and human disturbance factors, which had direct or indirect effects on species survival and reproduction, were all included in the model. Among them, elevation was the most important environmental variables affecting the suitability of habitats of three species. Temperature‐related factor was another important predictor. The high (>60%) suitable habitat areas for Upland buzzard, Saker falcon, and Himalayan vulture were 73,017.63, 40,732.78, and 61,654.33 km2, respectively, accounted for 59.32%, 33.09%, and 50.08% of the Sanjiangyuan National Park and their total suitable area (i.e., the sum area of high and moderate habitats) reached 96.07%, 60.59%, and 93.70%, respectively. Besides, the three species have overlapping areas for the suitable habitats, which means that overlapping areas should be highly valued and protected. Therefore, understanding the distribution of suitable habitats of the three raptors can provide useful information and reasonable reference for us to put forward suggestions for their protection and regional management.  相似文献   
14.
The legal and illegal use of organophosphorus and carbamate pesticides represents one of many threats to birds. The activity of the cholinesterase enzyme in plasma is used as a non‐destructive biomarker to diagnose the exposure of birds to these pesticides. Scavengers are one of the most important bird groups threatened by the use of baits poisoned with anticholinesterase pesticides. Knowledge of the characteristics of this enzyme in each bird species is crucial, as several studies indicate that more than one cholinesterase form may be present in the plasma of birds. In this study, cholinesterase activity was characterized in the plasma of the Eurasian Griffon Vulture Gyps fulvus by using several substrates and inhibitors of the enzyme, and its normal activity value was also determined. The in vitro sensitivity of Gyps fulvus plasma cholinesterase to carbamate insecticides (aldicarb, carbaryl and methomyl) was also investigated. The results indicated that propionylthiocholine iodide was the preferred substrate to determine plasma cholinesterase activity, followed by acetylcholine iodide and S‐butyrylcholine iodide, and acetylcholinesterase was the predominant enzymatic activity in Gyps fulvus plasma. Aldicarb was the most potent in vitro inhibitor of plasma cholinesterase activity in this species. However, cholinesterase enzymatic activity was significantly inhibited by all tested carbamates, providing further evidence that this biomarker is a suitable tool to monitor the exposure to these poisons in the field, highlighting its utility in conservation programmes.  相似文献   
15.
To obtain polymorphic molecular markers for population genetic and conservation studies in the Eurasian vulture Gyps fulvus populations, we screened a size‐selected partial genomic library enriched for microsatellites with dinucleotide motifs. A total of five polymorphic markers were obtained. The number of alleles ranged from two to nine and the observed and expected heterozygosity were very similar. These markers will be very useful for studying population structure and to evaluate conservation programmes.  相似文献   
16.
C. J. Skead 《Ostrich》2013,84(2):155-165
Hooded Vultures Necrosyrtes monachus are critically endangered but little is known of their year-round use of nests or whether other species usurp Hooded Vulture nest sites. We investigated visitation rates by Hooded Vultures and other species (including potential nest predators and usurpers) to examine their effect on Hooded Vulture breeding success. We present observations of 33 species recorded by camera traps at 12 Hooded Vulture nests over a total of 93 nest-months (2 095 nest-days). Several pairs of Hooded Vultures visited their nests regularly during the non-breeding season, some adding nesting material, highlighting that pairs visited their nest(s) year round. Egyptian Geese Alopochen aegyptiaca, potential usurpers of raptor nests, were present at occupied and unoccupied Hooded Vulture nests, but we recorded no usurpation of nests by Egyptian Geese and they had no impact on vulture breeding success. Hooded Vulture breeding failure was linked to two species only: camera-trap imagery recorded one case of predation of a vulture egg by a Chacma Baboon Papio ursinus, and one case of a Martial Eagle Polemaetus bellicosus predating a vulture nestling. We recommend expanding the Hooded Vulture nest monitoring programme to include more pairs.  相似文献   
17.
Ron W. Summers 《Ostrich》2013,84(2):167-173
Summers, R. W. 1994. The migration patterns of the Purple Sandpiper Calidris maritima. Ostrich 65: 167–173.

The Purple Sandpiper breeds largely in the Arctic, and winters (boreal season) on the rocky shores of the north Atlantic, further north than any other sandpiper. As the populations from Canada, Greenland, Iceland, Svalbard, Norway and Russia differ in wing and bill lengths it is possible to match measurements taken from breeding birds with samples of birds caught in winter. Ringing recoveries, especially from colour marked birds, have also helped to determine migration routes and wintering areas. Four populations move to the nearest ice-free coast. Two populations move south of the nearest ice-free coast, being replaced by larger birds from a more northerly population (“chain migration”). Only the north Canadian population is believed to migrate a long distance, “leap-frogging” other winter populations. These patterns are discussed in relation to theories for the migration patterns of waders.  相似文献   
18.
秃鹫(Aegypius monachus)被世界自然保护联盟(IUCN)列为近危物种。每年冬季或者早春在渤海湾都会救护到因体质较弱而无法飞行的秃鹫,为了对秃鹫及其迁徙路线进行更有效的保护,于2016年春季对两只救护放飞秃鹫(ID1051和ID2016),利用卫星跟踪技术研究其迁徙路线和活动区,旨在为秃鹫的救护和保护提供基础资料。结果表明,ID1051和ID2016都迁徙到蒙古国的布尔干省和后杭爱省交界处,行程分别为2 200 km和2 400 km。ID2016在度夏初期、中期和后期的活动区面积(50%Fixed Kernel),分别为31 261.01km^2、1 492.96 km2和11 027.70 km^2。秃鹫在迁徙过程中主要时间在静息,其次是飞行和寻觅行为。在0至7时和19至24时,即晨昏和夜间秃鹫都处于静止状态。从8时开始,秃鹫开始活动,并在12和13时达到活动高峰,随后活动逐渐趋缓,直至18时趋于静止状态。本文提供了秃鹫的春季迁徙路线以及重要中途停歇地,为秃鹫的救护和保护提供了基础资料。  相似文献   
19.
The active acquisition of plumage cosmetic coloration by iron oxides has been described in several bird species (notably the Bearded Vulture Gypaetus barbatus, but also in cranes, pelicans and other vulture species) but its function remains controversial. We tested the hypothesis that iron oxide acquired through mud bathing protects feathers from wear. We experimentally stained 13 breast feathers collected from two White Storks Ciconia ciconia with mud from a ferruginous pond regularly used by Bearded Vultures, while another 13 feathers (controls) were treated with water. All feathers were exposed to a controlled physical abrasion treatment. We found no differences in wear between control and stained feathers, which is counter to predictions of the wear protection hypothesis for the acquisition of this cosmetic plumage coloration.  相似文献   
20.
动物中普遍存在雌雄个体身体大小的性二态现象。了解近缘种之间身体大小性二态现象的差异,可为深入探讨身体大小性二态现象的潜在驱动机制提供证据。国外对欧亚大山雀(Parus major)的研究发现,其喙长、跗跖长、翅长等 6 项身体大小指标存在着明显的性二态,且喙长的性二态存在季节间差异。大山雀(P. cinereus)曾被作为欧亚大山雀的一个亚种,其形态和行为与欧亚大山雀存在着诸多相似之处。为探讨大山雀是否也存在身体大小性二态及季节性差异,本研究分析了 2018 至 2020 年间在河南董寨国家级自然保护区捕捉的 226 只(雌性 96 只和雄性 130 只)大山雀的喙长、头喙长、跗跖长、翅长、尾长和体长这 6 项体征指标的两性差异及其季节变化。结果显示,大山雀上述 6 项身体大小指标均存在不同程度的性二态现象,且雄性个体仅喙长与雌性的差异不显著,其余 5 项指标均显著大于雌性。此外,身体大小指标的两性差异不随季节显著变化,但两性的跗跖长在秋季均显著短于冬季和繁殖季,尾长在繁殖季均显著长于秋季和冬季。上述结果表明,大山雀身体大小的性二态及其季节性差异与欧亚大山雀并不完全相似。无论其身体大小存在性二态和季节变化的原因,还是其与欧亚大山雀在身体大小性二态模式上的差别,都有待今后进一步的研究。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号