Yang H.-Y.,Beijing Normal University |
Yang H.-Y.,University of Groningen |
Chen B.,Building 1 |
Barter M.,Anhui University of Science and Technology |
And 5 more authors.
Bird Conservation International | Year: 2011
The coast of Bohai Bay, north-western Yellow Sea, is critical for waterbirds migrating along the East Asia-Australasian Flyway. Between 1994 and 2010, a total of 450 km2 of offshore area, including 218 km 2 of intertidal flats (one third of the original tidal area in the bay), has been reclaimed along the bay for two industrial projects. This has caused the northward migrants to become concentrated in an ever smaller remaining area, our core study site. The spring peak numbers of two Red Knot subspecies in the East Asia-Australasian Flyway, Calidris canutus piersmai and C. c. rogersi, in this so far little affected area increased from 13% in 2007 to 62% in 2010 of the global populations; the spring peak numbers of Curlew Sandpiper C. ferruginea increased from 3% in 2007 to 23% in 2010 of the flyway population. The decline in the extent of intertidal mudflats also affected Relict Gulls Larus relictus, listed by IUCN as "Vulnerable"; during normal winters 56% of the global population moved from the wintering habitats that were removed in Tianjin to the relatively intact areas around Tangshan. Densities of wintering Eurasian Curlew Numenius arquata, and spring-staging Broad-billed Sandpiper Limicola falcinellus and Sanderling Calidris alba have also increased in the remaining areas. With the proposed continuation of land reclamation in Bohai Bay, we predict waterbird densities in the remaining areas to increase to a point of collapse. To evaluate the future of these fragile, shared international resources, it is vital to promote an immediate conservation action plan for the remaining coastal wetlands in this region, and continued population monitoring to determine the effects of this action. Copyright © 2011 BirdLife International.
Sundar K.S.G.,International Crane Foundation |
Sundar K.S.G.,University of Minnesota |
Subramanya S.,University of Agricultural Sciences, Bangalore
Waterbirds | Year: 2010
The Indian subcontinent has the world's highest cropland cover per unit area with rice (Oryza sativa) being the second-most important crop, and is home to nearly 1,300 species of birds. The significance of rice fields as bird habitat in the region is not well understood and the subject is reviewed using a combination of published and secondary information. Rice fields in the subcontinent are used by at least 351 species, although only 2.7% of birds occurring in the subcontinent breed in rice fields. The spread of rice cultivation and its attendant secondary habitats may have contributed to the increase in range and population of 64 common species but is threatening hundreds of other species, many of conservation concern. Most work in the region has focused on birds as pests of rice. Few studies have been conducted on the habits of birds that use rice fields and fewer still have compared how rice fields and similar natural habitats differ. Although rice harvesting has caused nest mortality for breeding birds, there is no comparable information from natural habitats. The guild structure of birds in rice fields is similar to that overall in the region except for a higher representation of carnivores. Rice fields are used primarily by grassland and wetland species. There are large information gaps that require filling to be able to ascertain the utility or impact of rice fields to bird populations and, thus, many research opportunities.
SundarGopi K.S.,University of Minnesota |
Kittur S.A.,International Crane Foundation
Landscape Ecology | Year: 2012
Biodiversity persistence in non-woody tropical farmlands is poorly explored, and multi-species assessments with robust landscape-scale designs are sparse. Modeled species occupancy in agricultural mosaics is affected by multiple factors including survey methods (convenience-based versus systematic), landscape-scale agriculture-related variables, and extent of remnant habitat. Changes in seasonal crops can additionally alter landscape and habitat conditions thereby influencing species occupancy. We investigated how these factors affect modeled occupancy of 56 resident bird species using a landscape-scale multi-season occupancy framework across 24 intensively cultivated and human-dominated districts in Uttar Pradesh state, north India. Convenience-based roadside observations provided considerable differences in occupancy estimates and associations with remnant habitat and intensity of cultivation relative to systematic transect counts, and appeared to bias results to roadside conditions. Modeled occupancy of only open-area species improved with increasing intensity of cultivation, while remnant habitat improved modeled occupancy of scrubland, wetland and woodland species. Strong seasonal differences in occupancy were apparent for most species across all habitat guilds. Further habitat loss will be most detrimental to resident scrubland, wetland and woodland species. Uttar Pradesh's agricultural landscape has a high conservation value, but will require a landscape-level approach to maintain the observed high species richness. Obtaining ecological information from unexplored landscapes using robust landscape-scale surveys offers substantial advantages to understand factors affecting species occupancy, and is necessary for efficient conservation planning. © 2011 Springer Science+Business Media B.V.
Wu J.-D.,Jiangxi Poyang Lake National Nature Reserve |
Li F.-S.,International Crane Foundation |
James B.,University of Wisconsin - Madison
Wetland Science | Year: 2013
Poyang Lake is the largest freshwater lake in China and globally famous for its birdlife. The rich food resources provided by this wetland's emergent and submerged aquatic plant diversity is a major reason that hundreds of thousands of migratory birds travel to Poyang Lake every winter; on average more than 400 000 water-birds make Poyang Lake their winter home. Poyang Lake is extremely important to Critically Endangered Siberian Cranes Grus leucogeranus, as 3 000-4 000 Siberian Cranes, or over 98% of the world's population of this species spend winter here each year. The International Crane Foundation and the Poyang Lake National Nature Reserve collaborated to carry out a monitoring program from 1999 to 2010 in Sha Hu, one of nine sub-lakes of the Poyang Lake National Nature Reserve in Jiangxi Province of China. The objectives of the monitoring were to: record the number and location of the Siberian Cranes; determine the biomass of their aquatic food plants; and better understand relationship between foraging Siberian Cranes and their aquatic food plants as well water depth. Tubers of Vallisneria spp. were the main food of the Siberian Cranes during winter. Vegetation transects were set up to record numbers and biomass of Vallisneria spp. and their tubers. High vantage points that covered the whole Sha Hu were used to record number of Siberian Cranes and the water depth where the birds were foraging throughout the winter. The location of the birds was also mapped. During the 12 years, overall average number of Siberian Cranes was 46 birds, with winters in 2002, 2006 and 2009 over 90 birds. Within a winter, numbers of Siberian Cranes from November to January were relatively stable and the peak number of cranes occurred in December (120 birds). Siberian Cranes were seen mostly in the middle part by south of the lake, while very few recorded in northern and southern parts. The cranes were almost exclusively seen in the submerged vegetation communities dominated by Vallisneria spp. and Potamogeton spp. From 1999 to 2010, the average dry weight of Vallisneria tubers at Sha Hu was 5.92 g/m2, in 2005, 2006 and 2008 about or over 12.00 g/m 2, while was 0.10 g/m2 in 2010. For the 12 years of data, the correlation between the number of Siberian Cranes during December and January and tuber dry weight was not significant, with r=0.231, indicating Vallisneria tubers, at least alone, were likely not a limiting factor to the wintering Siberian Cranes. Areas with water depth of 5-27 cm had the highest number of the cranes (58%), followed by areas with water depth of 40-45 cm (31%). In total, 91% of the Siberian Cranes were found in areas with water depth of 5-45 cm. The big flood at Poyang Lake in summer of 2010 had a significant impact on aquatic plant food, forcing Siberian Cranes seeking alternative food sources in sedge/grass zones.
Beilfuss R.,International Crane Foundation |
Beilfuss R.,University of Wisconsin - Madison
International Journal of River Basin Management | Year: 2010
Environmental flow releases from hydropower dams have gained worldwide attention in recent years as a tool for improving hydrological conditions and reversing adverse ecological and socio-economic changes associated with regulated rivers. Few studies have focused on the potential for implementing downstream environmental flows within the constraints of existing infrastructure and hydropower production commitments. A simulation model, using a 97-year historical flow series, was developed to assess the trade-offs between environmental flow scenarios and hydropower generation in the Lower Zambezi Basin, Mozambique - a river-floodplain system of immense biodiversity and socio-economic value. Water availability for generating environmental flow releases from the Cahora Bassa Dam to improve downstream hydrological conditions is constrained by water demand for guaranteed energy supply to electricity users ('firm power'). Recreating the natural flood hydrograph for the Lower Zambezi River by mimicking unregulated mean monthly flows is not possible without substantial reductions in the firm power reliability and total power production. However, a variety of options are available for generating high-volume flood pulses during the normal flood season months of December to March. For example, a mean monthly outflow of 5000 m 3 s -1 in December was generated in 93.4% of all years within industry-acceptable thresholds for the firm power reliability and with <3% reduction in power generation. Under baseline conditions, these same outflows would occur in only 18.7% of all years. Improved firm power reliability and energy generation for a given environmental flow scenario are attainable by establishing minimum reservoir elevation thresholds that curtail environmental flow releases during drought periods. Outflows of 5000-8000 m 3 s -1 in February were realized within acceptable firm power levels, for example, using a reservoir elevation threshold of 316 m. Increasing the outflow capacity at the Cahora Bassa Dam to enable reservoir management as a run-of-river scheme during flooding events could also substantially improve downstream flow patterns and hydropower output. © 2010 International Association for Hydro-Environment Engineering and Research.