A survey of Ardeid nesting colonies in central Guizhou,southwestern China in May 2006,which covered about one-third of the area of this province,recorded a total of 1587 nests of five species,i.e.,Little Egret (Egrett...A survey of Ardeid nesting colonies in central Guizhou,southwestern China in May 2006,which covered about one-third of the area of this province,recorded a total of 1587 nests of five species,i.e.,Little Egret (Egretta garzetta),Cattle Egret (Bubulcus ibis),Chinese Pond Heron (Ardeola bacchus),Black-crowned Night Heron (Nycticorax nycticorax) and Grey Heron (Ardea cinerea) at 11 nesting colonies.The largest colonies were recorded at Fengyunyan and Yanfu resorts,the smallest one at Luobolin.The Little Egret was the dominant nesting species (49.7% of the total number of nests) and the Grey Heron was the least abundant (0.1%).All nesting colonies were located in the northern and central parts of Guizhou;no colonies were found in the Leigongshan area,the southern part of this province.The distribution of nesting colonies in central Guizhou appears to be affected by the relative composition of winter (wheat and vegetable) and summer (rice) crops during the breeding season (between late March and June).No colonies were found around farmlands with winter crops and most colonies were situated around rice paddies.The farmland use pattern is affected by rainfall.The summer crop is delayed if the rainy season starts late and the rainfall is light.Priority for conservation of the Ardeids in central Guizhou should be given to the larger colonies i.e.,Yanfu and Fengyunyan resorts.展开更多
Based on the analysis of the enrichment char- acteristics of Hg and MeHg in bird feathers from Caohai National Nature Reserve in Guizhou, the risks of Hg pol- lution to the birds from Caohai wetland have been evalu- a...Based on the analysis of the enrichment char- acteristics of Hg and MeHg in bird feathers from Caohai National Nature Reserve in Guizhou, the risks of Hg pol- lution to the birds from Caohai wetland have been evalu- ated. The total Hg content of bird feathers ranges from 40 to 5058 ng/g.vyjth an average of 924 ng/g. The content of MeHg is significantly correlated with total Hg （r = 0.68,p 〈 0.01）, and the content are among 0.75 and 113 ng/g. The total Hg content in the birds feathers is significantly dependent on their feeding habits, which is mainly in accordance with the following rule： carnivorous birds 〉 omnivorous birds that are mainly carnivo- rous 〉 omnivorous birds that are mainly herbivorous. There are also differences in the Hg enrichment ability in the different parts of bird feathers, and the total Hg and MeHg content in the wing feathers are significantly higher than that in the other parts of feathers. The bioaccumula- tion coefficients of aqueous Hg and MeHg by bird feathers are 0.9 × 10︿4-112.13× 10︿4 （mean value is 20.47 ×10︿4）and 0.47 × 10︿4-70.4 × 10︿4 （mean value is 9.52 × 10︿4）, respectively. Although the whole Hg level in Caohai bird feathers is not too high, the Hg content in some carnivorous birds exceeds over or approaches the abnormal threshold when birds are breeding （5μg/g）, which indicates that the birds in Caohai wetland are faced with some risks of ecological Hg pollution.展开更多
One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in specie...One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].展开更多
文摘A survey of Ardeid nesting colonies in central Guizhou,southwestern China in May 2006,which covered about one-third of the area of this province,recorded a total of 1587 nests of five species,i.e.,Little Egret (Egretta garzetta),Cattle Egret (Bubulcus ibis),Chinese Pond Heron (Ardeola bacchus),Black-crowned Night Heron (Nycticorax nycticorax) and Grey Heron (Ardea cinerea) at 11 nesting colonies.The largest colonies were recorded at Fengyunyan and Yanfu resorts,the smallest one at Luobolin.The Little Egret was the dominant nesting species (49.7% of the total number of nests) and the Grey Heron was the least abundant (0.1%).All nesting colonies were located in the northern and central parts of Guizhou;no colonies were found in the Leigongshan area,the southern part of this province.The distribution of nesting colonies in central Guizhou appears to be affected by the relative composition of winter (wheat and vegetable) and summer (rice) crops during the breeding season (between late March and June).No colonies were found around farmlands with winter crops and most colonies were situated around rice paddies.The farmland use pattern is affected by rainfall.The summer crop is delayed if the rainy season starts late and the rainfall is light.Priority for conservation of the Ardeids in central Guizhou should be given to the larger colonies i.e.,Yanfu and Fengyunyan resorts.
基金supported by the National Natural Science Foundation of China (No. 41363007)
文摘Based on the analysis of the enrichment char- acteristics of Hg and MeHg in bird feathers from Caohai National Nature Reserve in Guizhou, the risks of Hg pol- lution to the birds from Caohai wetland have been evalu- ated. The total Hg content of bird feathers ranges from 40 to 5058 ng/g.vyjth an average of 924 ng/g. The content of MeHg is significantly correlated with total Hg （r = 0.68,p 〈 0.01）, and the content are among 0.75 and 113 ng/g. The total Hg content in the birds feathers is significantly dependent on their feeding habits, which is mainly in accordance with the following rule： carnivorous birds 〉 omnivorous birds that are mainly carnivo- rous 〉 omnivorous birds that are mainly herbivorous. There are also differences in the Hg enrichment ability in the different parts of bird feathers, and the total Hg and MeHg content in the wing feathers are significantly higher than that in the other parts of feathers. The bioaccumula- tion coefficients of aqueous Hg and MeHg by bird feathers are 0.9 × 10︿4-112.13× 10︿4 （mean value is 20.47 ×10︿4）and 0.47 × 10︿4-70.4 × 10︿4 （mean value is 9.52 × 10︿4）, respectively. Although the whole Hg level in Caohai bird feathers is not too high, the Hg content in some carnivorous birds exceeds over or approaches the abnormal threshold when birds are breeding （5μg/g）, which indicates that the birds in Caohai wetland are faced with some risks of ecological Hg pollution.
文摘One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].
