Shifts in bird ranges and conservation priorities in China under climate change

thinning and background selection methods for sampling bias correction [46, 47, 61]. For vari- able selection in this study, we removed highly correlated and low contribution variables to avoid overfitting [64]. However, we found that some island (the Taiwan Island and the Hainan Island) and endemic species (18 island species have a 0.26 training AUC reduction on average) had poor performance perhaps due to their small sampling background (island areas) [73]. This suggests that more species-specific modeling methods should be applied for species with special distribution pattern. We believe that according to different research goals, comprehen- sive consideration of various correction methods can maximize the advantages of citizen scien- tific data in distribution modelling, not to say the low economic cost for data collection. 4.2 Uncertainty of bird survival in China under climate change Our results reveal that the impact of climate change on the distribution of birds is significant in China, both reducing or expanding in the range area and shifting in its elevation or latitude. In general, our assessment indicated that: 1) more birds would have opportunities to expand their ranges than would face risks related to habitat loss in China due to climate change in the next 50 years, similar to the report on a national-scale assessment of more than 3,000 species in the U.K. [74]; 2) most bird species may move to northeast or northwest China and high alti- tude areas (this trend is similar to the review results summarized by Davis and Shaw, 2001 and

Pearce-Higgins et al., 2011 [53, 74]). 3) compared with the range change of resident birds, the range area of migratory species is more likely to move northward and decrease in area, which suggests that migratory birds may be more threatened by future climate change. Special attention should be paid to the 25% of the birds that may reduce the range size. For example, Red-crowned Crane (G. japonensis), a popular endangered species which has lost 92% wintering range in past 30 years [75], may face the risk of losing 94% of its existing range area in the next 50 years (S2 Fig). The current conservation strategy on the species recovery may not be adequate to deal with the threat of future climate change. Close monitoring to the population and investigation to its potential future habitats is needed [76]. For the 75% of the birds that may expand the range size, however, the situation is not neces- sarily positive either if their future climatic suitable habitats are away from protected areas or toward more developed land. With the shift and expansion of the distribution range, bird spe- cies may enter a climatically suitable, but high-intensity populated habitats, and thus face the threat of poaching and illegal trade, urbanization, and industrialization. For example, all of the top ten “expanders” under RCP 8.5 may move to developed and densely populated areas, such as the Pearl River Delta and surrounding Beijing suburbs (S2 Fig). 4.3 A more rigorous conservation system is needed for China

While species range shifting, the conservation priority areas also shift with the future climate influence. We identified the future conservation priority areas for birds in China using top 30% threshold to meet the target of land conservation proposed in Zero Draft of the Post-2020 Global Biodiversity Framework [77]. The national nature reserves only cover 6.73% of priority areas for RCP 2.6 and 9.9% for RCP 8.5, which is inadequate to cope with the climate impact. Many important habitats remain as conservation gaps. For example, many critical coastal wet- lands are not listed as nature reserves [36], where many severely affected bird species may move to (S2 Fig). More protection is also needed in in the Northeast Plain, Bohai Rim/North China Plain, Karakoram Mountain, Lower Yangtze Basin, Southwestern Mountains and northern Xinjiang areas. Policy-makers must integrate these research results combined from different taxa so that future NNR systems in China can mitigate the effects of climate change [18]. PLOS ONE Bird range changes call for innovative conservation in China PLOS ONE | https://doi.org/10.1371/journal.pone.0240225 October 8, 2020 14 / 20