Range contraction of the Yangtze finless porpoise inferred from classic Chinese poems.

Understanding and quantifying the historical range of threatened species can help inform conservation and restoration¹. Most studies use specimen data, molecular evidence or past surveys to reconstruct historical ranges. However, historical documents provide a unique opportunity to reconstruct species' distributions and ranges, offering new perspectives on changes in biodiversity. Several recent studies have shown that historical documents, such as standard histories and gazetteers² or compendia of the genealogy of plants or animals³, can be used to reconstruct species distributions. For example, compendium records in China revealed severe and rapid contraction of mammalian megafauna ranges over the past two millenia⁴. Here, we examine an unusual source of information: classic Chinese poetry. From 724 ancient poems containing references to the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), we infer that the range of this subspecies has contracted by at least 65% over the past 1400 years.