Analysis of classical Chinese poetry has revealed that writers were well-versed in the decline of critically endangered river porpoises in the Yangtze River, going all the way back to the Tang Dynasty. In fact, verses reveal pretty clearly how the marine mammal’s range has contracted in 1,400 years. The Yangtze finless porpoise (Neophocaena asiaeorientalis) is considered critically endangered by the IUCN due to habitat loss, pollution and increasing shipping and other uses in the river. But it’s sometimes difficult to track the true extent of the loss in range of a species due to the relatively short time that numbers have been formally tracked by scientists. Other researchers have made use of historical documents to track species numbers in deep time, though. In the case of the Yangtze finless porpoise, classical poetry may provide the answer. Researchers combed poetry dating back 1,400 years to the Tang Dynasty. From this period on, they found 724 poems that mentioned the species. Half of these poems had specific location information, which the researchers then plotted on maps to determine the historic distribution of the species, extending their knowledge back more than a millennium. This study revealed that the range of these porpoises has dropped about 65% since the Tang Dynasty, the sharpest drop occurring between the Qing Dynasty of 1636 to 1912 and the modern era.
