Baer’s Pochard is a poorly known migratory diving duck that was formerly widespread in eastern Asia. Since the 1980s it has suffered a precipitous decline throughout its range, but the causes of this and the current population size are largely unknown. Following uplisting to Critically Endangered on the IUCN Red List in 2012, an International Single Species Action Plan (ISSAP) was prepared in 2014 and adopted by the East Asian – Australasian Flyway Partnership (EAAFP) in 2015 and Convention on the Conservation of Migratory Species of Wild Animals (CMS) in 2017.

Hengshui Lake Wetland is a typical inland freshwater wetland ecosystem in the North China Plain. It is an important site on the East Asian- Australian Flyway of migrating birds, and provides important habitats for Baer’s Pochard (BPs). Since 2000 such a species has been observed several times in Hengshui Lake Wetland, but there is a lack of routine monitoring and research. Fifty monitoring sites have been set up in Hengshui Lake Wetland and weekly surveys have been conducted since late March 2017. The results show that there are significant spatial and temporal differences in the population of Baer’s Pochard: 1) The number of individuals was between 70 and 135 in spring, autumn, and winter, but less than 20 in summer; 2) The number of male individuals was more than female in most of the year, but the sex ratio of male to female was close to 1:1 in April and early May; 3) BPs mainly stayed on the lake in spring and summer, in Fudongpaihe Canal in autumn, and at a few unfrozen open water spots in winter .