Avian Altitudinal Migration

Information on avian species’ distribution and abundance is crucial to the study of ecology and conservation. This information is challenging to derive as available data are generally limited in either spatial or temporal coverage. For this, citizen science data, which has wide spatiotemporal coverage, have been incorporated into a spatial modelling framework to predicted species’ distribution and abundance in North America. However, few efforts had been put to employ this framework in other regions, such as Taiwan, which possesses abundant biodiversity and adequate observation data. In this study, we adapted the spatial modelling framework to produce the year-round and range-wide avian distributional information using citizen science data in Taiwan.

To demonstrate the framework, White-eared Sibia (Heterophasia auricularis) was selected as the target species due to its conspicuous vocalizations, making it easily detectable in all seasons. We produced distribution maps at local scale spatial resolutions across the main island of Taiwan and weekly temporal resolution across the full annual cycle. Further, intra-annual estimates of distributional range, area, and elevation were derived. Elevation distributions estimated by the model showed a substantial difference in the breeding (mean elevation 1,630 m) and non-breeding (mean elevation 1,300 m) season. The elevation distribution of the breeding population based on the independently collected data, Taiwan Breeding Bird Survey, has a similar pattern (mean elevation 1,530 m). The information provided fills the gap of species distribution and altitudinal change, especially during less-studied migration and non-breeding season. Ultimately, this framework can potentially be the standard framework for mapping bird distribution on the main island of Taiwan.