Habitat Loss and Migratory Shorebirds

Populations of migratory animals are in decline around the world. Four human-caused threats, namely habitat loss and degradation, overexploitation, interruption of migratory movements, and global climate change, are widely recognized as the major drivers of past and current declines.

Few groups of migratory species have declined as precipitously in recent decades as have the coastal shorebirds migrating along the East Asian-Australasian Flyway (EAAF). Among the ~20 species that occur regularly along the Pacific Coast of Asia, 11 species are now listed as threatened or near threatened by the IUCN Red List. The cause of the shorebird declines in the EAAF has been largely attributed to the rapid loss of tidal flat habitat in the Yellow Sea region, which most coastal shorebirds use to rest and refuel during their long-distance migrations. The drastic changes in both habitats and populations pose great challenges to saving these species, but they also provide an excellent opportunity to understand the effects of habitat loss on populations of migratory animals, at both local and global scales.

At the local scale, our researchers are mapping the detailed foraging patterns of different shorebird species at stopover sites, identifying the key foraging areas to conserve. Preliminary results suggest that the areas used most intensively by the birds are also the areas most vulnerable to development and other human-caused threats. Our researchers are working closely with other research collaborators, local NGOs, and governmental agencies in China to secure the key habitats of these birds and to improve degraded areas.

Globally, our researchers are combining individual tracking methods and mathematical modeling to investigate the migration patterns of various shorebird species, the mechanisms determining their migration strategies, and the demographic connectivity of migratory populations. They are particularly interested in studying how changes experienced by these birds at one stage of their migratory life cycle affect other stages, and how the overall population is likely to respond to these local changes.

Researcher: Tong Mu

The Impacts of Hunting and Bycatch on Shorebird Populations in China

Globally, migratory shorebirds are experiencing massive population declines, often caused by human-induced changes to their habitats and stopover points. Bird populations that migrate along the East Asia-Australasia Flyway (EAAF) are experiencing the steepest declines, and, consequently, a high proportion of these shorebird species are listed as threatened or near threated by the IUCN Red List. The well-documented threats include habitat loss and habitat degradation, especially of the intertidal mudflats along the Yellow Sea. However, a significant source of bird mortality may be due to intentional hunting as well as unintentional capture of birds in tidal fishing nets – factors largely ignored to date.

Our field-based study investigates the combined effects of hunting and bycatch on shorebird populations across the entirety of China’s coast. By determining the density of mist nets, decoys, and tidal fishing nets and by monitoring the mortality rates of shorebirds in randomly selected stopover sites, we are able to estimate the magnitude of hunting and bycatch. Then, by developing population models, we can then quantify the effects of hunting and bycatch on shorebird populations. Our research will provide information critical to protecting declining populations of migratory shorebirds.  

Researcher: Dan Liang

Identifying Migration Pathways for Conservation Efforts

One of the major challenges in conserving migratory species is our lack of knowledge regarding their migration pathways and stopover regions, which is critical for designing protected areas. This problem is particularly acute for songbirds, the group with the largest population decline in North America over recent decades, as their small body sizes and nocturnal migration strategies limit the usage of tracking devices on them. Moreover, it is not known if such species favor particular areas when deciding where to rest and refuel during migration, and, if such crucial sites exist, whether the songbirds use them in consecutive years.

However, recent advancements in citizen-science data gathering and information technology have provided new tools to better understand the long-distance migration patterns of songbirds. Our researchers are investigating one of the world's largest citizen science databases, eBird, and utilizing weather radar technology to develop songbird migration models that can identify major stopover sites in North America. By assessing the land-use change and climate change impacts on those crucial stopover regions, we can identify the key sites and develop more effective conservation strategies for these birds.

Researcher: Fengyi Guo