Long-term changes in populations of rainforest birds in the Australia Wet Tropics bioregion: A climate-driven biodiversity emergency

trends in both midland (trend difference 0.043 ± 0.002, p<0.05) and upland specialists (trend difference 0.059 ± 0.002, p<0.05). Additionally, upland specialists have declined significantly more than midland specialists (trend difference 0.015 ± 0.002, p<0.05), suggesting that the pattern of decline increases with increasing elevation. Shifts in patterns of local abundance are species-specific and highly variable, often involving complex spatio-temporal and non-monotonic trends (for example, Brown Gerygone, see sup- plementary material). However, the overall multi-species trends that summarise the observed shifts in bird assemblages along the elevational gradient are what we would predict under a warming climate: there have been significant upslope shifts in bird abundance patterns across the 17 years of this study. We demonstrated this by examining the trends in local abundance for each group of elevational specialists in their original preferred elevation (baseline averaged abundance at each elevation across 1996–2003) and in the adjacent elevational bands over time. We predicted, for example, that lowland species should increase in the midlands, and upland species should decline at lower elevations. The observed spatial shifts in elevational dis- tribution and abundance are in accord with the earlier predictions based on distribution Fig 1. Trends in local abundance from 2000 to 2016 based on the multi-species indicators for a) all species, b) habitat generalists, c) regional endemic species and d)

rainforest specialists. Values are the multi-species index with SE (error bars) with the smoothed trend line with 95% CI (shaded area). https://doi.org/10.1371/journal.pone.0254307.g001 PLOS ONE Rainforest birds on escalator to extinction PLOS ONE | https://doi.org/10.1371/journal.pone.0254307 December 22, 2021 4 / 16