Determining the distribution loss of brown eared-pheasant (Crossoptilon mantchuricum) using historical data and potential distribution estimates.

We analyzed the synchronous relationship between forest cover and species distribution to explain the contraction in the distribution range of the brown eared-pheasant (Crossoptilon mantchuricum) in China. Historical resources can provide effective records for reconstructing long-term distribution dynamics. The brown eared-pheasant's historical distribution from 25 to 1947 CE, which included the three provinces of Shaanxi, Shanxi, and Hebei based on this species' habitat selection criteria, the history of the forests, ancient climate change records, and fossil data. The current species distribution covers Shaanxi, Shanxi, and Hebei provinces, as well as Beijing city, while Shanxi remains the center of the distribution area. MaxEnt model indicated that the suitable conditions of the brown eared-pheasant had retreated to the western regions of Shanxi and that the historical distribution area had reduced synchronously with the disappearance of local forest cover in Shanxi. We built a correlative relationship between the presence/absence of brown eared-pheasants and forest coverage and found that forest coverage in the north, northeast, central, and southeast areas of the Shanxi province were all less than 10% in 1911. Wild brown eared-pheasants are stable in the Luliang Mountains, where forest coverage reached 13.2% in 2000. Consequently, we concluded that the distribution of this species is primarily determined by vegetation conditions and that forest cover was the most significant determining factor.