Dong B.,East China Normal University |
Wu D.,East China Normal University |
Song G.,Chongming Dongtan National Nature Reserve |
Xie Y.,Shanghai Landscaping and City Appearance Administrative Bureau |
Wang T.,East China Normal University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010
From November 2008 to March 2009, an ecological investigation on the population of Reed Parrotbill (Paradoxornis heudei) was conducted in Chongming Dongtan, Shanghai. And during the study, a correlation analysis between the Reed Parrotbill population and environmental factors was undertaken. One-way ANOVA was used to analyze the impacts of smooth cordgarss (Spartina alterniflora) invasion and reed (Phragmites australis) harvesting on the distribution of Reed Parrotbill population and multi-regression analysis was used to analyze the relationship between the density, distribution of Reed Parrotbill and environmental factors. The results showed that the population density of Reed Parrotbill in Chongming Dongtan was (5.08 ±3.11) ind/hm2; the reed diameter positively correlated with density of Reed Parrotbill, the reed height and density had significantly positive impacts and food resource hold a positive impact to the distribution of Reed Parrotbill; smooth cordgrass had a negative impact to both density and the bird distribution. The habitat quality of Reed Parrotbill was on the decline due to the smooth cordgarss invasion and reed harvesting. Keeping some patches of reed in good growing condition could facilitate Reed Parrotbill wintering in Chongming Dongtan.
Choi C.,Fudan University |
Choi C.,Massey University |
Hua N.,Fudan University |
Gan X.,Fudan University |
And 4 more authors.
Journal of Field Ornithology | Year: 2011
Although most shorebirds exhibit deferred migration and deferred breeding during their first summer, Dunlins (Calidris alpina) migrate to breeding areas and breed during their first summer. First-year and adult Dunlins should, therefore, have similar fueling and molt patterns if energetic and physiological constraints are responsible for deferred migration. From 2006 to 2008, we examined the age structure of Dunlins during the nonbreeding season at Chongming Dongtan, an estuarine wetland in the Yangtze River estuary in east China, and examined the effects of date, age, and molt status on fuel deposition during migration and during the winter. The Dunlin population at Chongming Dongtan was composed primarily of first-year birds. Most adults and first-year birds arrived together in late August. Regression analyses indicated that age, date, and molt status affected fuel deposition (as indicated by body mass) of Dunlins. Adults had significantly greater fuel deposits than first-year Dunlins near the end of northward migration (May: adults 70.8 ± 6.4 g, first-year 63.8 ± 8.0 g) and at the start of southward migration (September: adults 50.2 ± 6.1 g, first-year 47.2 ± 4.9 g). Adults also had significantly higher fuel deposition rates than first-year Dunlins during northward migration. Nonetheless, first-year Dunlins migrate and breed in their first summer. Thus, other factors, such as migration distance and body size, may be more important in determining if first-year shorebirds defer migration during their first spring and summer. During boreal spring and autumn, first-year Dunlins in active body molt had greater body mass than those that had not initiated body molt or those in suspended molt, and premigratory fuel deposits for northward migration were greatest after prealternate molt was completed. These results suggest that body molt requires additional fuel deposits and imposes a constraint on fuel deposition for migratory flights. ©2011 The Authors. Journal of Field Ornithology ©2011 Association of Field Ornithologists.
Ma Z.,Fudan University |
Hua N.,Fudan University |
Zhang X.,Fudan University |
Guo H.,Fudan University |
And 4 more authors.
Ibis | Year: 2011
We assessed the effects of wind conditions on stopover decisions and fuel stores of migratory shorebirds at Chongming Dongtan in the south Yellow Sea along the East Asian-Australasian Flyway. In spring and autumn, wind directions differed among altitudes and wind speed generally increased with altitude. Numbers of shorebirds were related to wind effects at low altitudes (on the ground and at 300 and 800m above the ground), wind effects at 300m being the best predictor of shorebird numbers. In spring, total number of shorebirds and numbers of the four most abundant shorebird species were negatively related to wind assistance at low altitudes, more birds departing when tailwinds prevailed and more arriving when headwinds prevailed. In autumn, however, total number of shorebirds and numbers of the four most abundant species were positively related to wind assistance at low altitudes, more birds departing and more arriving with tailwinds than with headwinds. When tailwinds prevailed, the number of arriving birds was higher than the number of departing birds. The fuel stores of captured shorebirds, represented by their body mass, was related to wind effects and change in wind conditions between two consecutive days in both spring and autumn, captured birds being heavier when headwinds prevailed than in tailwind conditions, and when the wind conditions became less favourable for flight between two consecutive days. Our results suggest that wind conditions affect stopover decisions and fuel stores, and thus the optimal migration and fuel deposition strategies of migratory shorebirds. © 2011 The Authors. Ibis © 2011 British Ornithologists' Union.