No abstract

Migratory landbird population trends and threats in the East Asian-Australasian Flyway (EAAF) are poorly understood. To fill this knowledge gap, we investigated the effect of breeding habitat loss on the population trend for the Fairy Pitta (Pitta nympha), a migratory forest-breeding bird in the EAAF categorized as Vulnerable on the IUCN Red List. It has been assumed that this species is declining rapidly due to deforestation in its breeding range in Taiwan. We analyzed the change in Fairy Pitta population density across Taiwan from 2001 to 2017, and tested the effect of forest cover change on the species' abundance. We detected an average of 4.32 (95% CI: 1.96-6.68) individuals per km 2 in 2001, which has declined at an average annual rate of À8.31% (95% CI: À15.50%-À1.16%) during the study, and a minor change in forest cover (À0.22%) in Taiwan during this period. We found no significant effect of the forest cover trend on the population trend of the Fairy Pitta. This suggests that the drivers of population decline may not be related to deforestation in the breeding range, but potentially to breeding habitat degradation, habitat loss in the non-breeding range, or factors unrelated to habitat loss. Further studies are required to assess the major threats to this globally threatened species.

Migratory shorebirds rely on tidal flats as stopover sites for refueling and wintering. Taiwan is in the middle of the East Asian–Australasian Flyway, where the sandy/muddy shores on the western coast support thousands of migratory birds with important stopover habitats. Among these habitats, tidal flats are the most crucial habitats for shorebird survival. However, in the last century, the landscape has been largely altered for agriculture, aquaculture, and industrial development. To assess the current status of shorebird habitats, we evaluated landscape changes between the 1920s and 2020s based on historical topographic map data, Landsat Archive images, and the Normalized Difference Water Index. Our analysis showed that the area of tidal flats increased before the 1950s but has decreased since the 1980s. The area dropped rapidly from 459.72 km2 to 194.05 km2, and almost 60% of the tidal flat coverage has been lost in the last 60 years. These results indicate that the tidal wetlands in western Taiwan have reached an endangered status, as per the International Union for Conservation of Nature Red List of Ecosystems criteria. Although the decrease in speed seems to have slowed in recent decades, energy and industrial development still threaten tidal wetlands.