Suitable Habitat Dynamics of Wintering Geese in a Large Floodplain Wetland: Insights from Flood Duration

Simulation Modeling Unveils the Unalike Effects of Alternative Strategies for Waterbird Conservation in the Coastal Wetlands of Sardinia (Italy)

The Sardinian wetlands (Italy) act as stopover sites for many migratory birds along the central eastern Mediterranean bird flyway. These wetlands are now severely threatened by human activities and climate change. Accordingly, we built a simulation framework to predict the effects of several counterfactual and management scenarios on the level of avian diversity in the coastal wetlands of Sardinia. We found that the alpha avian diversity (i.e., the mean number of avian species per wetland) is destined to (a) decrease due to the most likely increase in water salinity, water discharges, and tourism pressure; and (b) halve (from 14.9 to 7.4, with 9 wetlands out of 22 predicted to host only between two and five waterbird species) in the worst possible scenario. However, the results also showed that proper management strategies could prevent and reverse such outcomes. Restrictions on tourism activities, water desalination, prevention of future saltwater intrusions, and the prohibition of water discharges could markedly favor the avian diversity in these wetlands, with an expected increase in the alpha avian diversity from 14.9 to 24.8 (and 10 wetlands out of 22 predicted to host from 29 to 32 waterbird species) in the best possible scenario. The importance of our results could be emphasized in the management plans of these important wetlands, most of which belong to the Natura 2000 network.

An integrated model for prediction of hydrologic anomalies for habitat suitability of overwintering geese in a large floodplain wetland, China

Climate anomalies and increasing human activities cause a high frequency of extreme hydrological events in wetlands, which has put waterbirds under greater survival pressure than ever. Therefore, it is crucial to predict the impact of this phenomenon on the habitat suitability of waterbirds. This study investigated the response of the goose distribution probability to hydrological variations using the flood duration index (FD), enhanced vegetation index (EVI), and waterbirds GPS tracking data in Poyang Lake. An overwintering geese habitat suitability index (HSI) is built based on the FD, EVI, and threat index and verifies the accuracy of the model simulation. Then, the effects of drought and flood on the goose habitat especially sub-lakes with different connectivity were analyzed. The findings reveal that in dry and flood years, geese will broaden their range of feeding vegetation (more fresh or mature vegetation) in response to environmental deterioration. Both drought and flood can lead to a decline in the HSI, especially flood. Connected sub-lakes are more vulnerable to hydrological anomalies than controlled sub-lakes. This research establishes a scientific foundation for floodplain wetland hydrology management and waterbird conservation.

Potential Habitats and Their Conservation Status for Swan Geese (Anser cygnoides) along the East Asian Flyway

Habitats provide essential space for migratory birds to survive and reproduce. Identifying potential habitats in annual cycle stages and their influencing factors is indispensable for conservation along the flyway. In this study, we obtained satellite tracking of eight swan geese (Anser cygnoides) wintering at Poyang Lake (28°57′4.2″, 116°21′53.36″) from 2019 to 2020. Using the Maximum Entropy species distribution model, we investigated the potential habitats distribution of the swan geese during their migration cycle. We analyzed the relative contribution of various environmental factors to habitat suitability and conservation status for each potential habitat along the flyway. Our results show that the primary wintering grounds of swan geese are located in the middle and lower reaches of the Yangtze River. Stopover sites were widely distributed, mainly in the Bohai Rim, the middle reaches of the Yellow River, and the Northeast Plain, and extended westward to Inner Mongolia and Mongolia. Breeding grounds are mainly in Inner Mongolia and eastern Mongolia, while some are scattered in Mongolia’s central and western. The contribution rates of major environmental factors are different in breeding grounds, stopover sites, and wintering grounds. Breeding grounds were influenced by slope, elevation, and temperature. Slope, human footprint index, and temperature were the main factors that affected stopover sites. Wintering grounds were determined by land use, elevation, and precipitation. The conservation status of habitats is 9.6% for breeding grounds, 9.2% for wintering grounds, and 5.3% for stopover sites. Our findings thus provide a critically international assessment of potential habitats protection for geese species on the East Asian Flyway.