them onto their back when coming back. If water levels are elevated by heavy rainfall or human activity, females increase the height of the nest to avoid flooding. During the hottest days, females often stand on the nest and shelter eggs from the strong sunlight, whilst allowing circulation of air around them. Females also take water into their plumage and use it to cool the eggs. The incubation lasted for 23-26 days. Studies have shown that the nest survival rate of Baer's pochards is about 14–45%, and each clutch may lose one to nine eggs. About 20-30% of eggs hatched successfully, and 3–16 young fledged per nest. There are three major reasons contributing to the failure, including nest desertion (abandoned by parents), nest predation (mainly by Siberian Weasels) and flooding. The proportion of these causes varies among years. In addition, most of the breeding sites in Wuhan are Crayfish farms, the farming work and eggs collection may also be hindrances. Biological interaction Incomplete inter- and intra-specific brood parasitism were found in Baer's pochard. In , Baer's pochards could parasitize gadwall and common pochard, and may be parasitized by common pochard. In Wuhan, Baer's pochard shares breeding sites with cotton teal, eastern spot-billed duck and mallard. Interspecific brood parasitism was not observed. Intraspecific parasitic was found in Wuhan. If caught, the parasite will get attacked by the host. Baer's pochard has hybridized with lesser scaup, common pochard, ferruginous duck, New Zealand scaup, chestnut teal and wood duck in captivity. Ferruginous duck was observed displaying to Baer's pochards several times in China and South Korea. Some individuals showed mixed characteristics of common, ferruginous and Baer's pochards, so they may be currently hybridising in the wild. The Baer's pochard has declined sharply in recent years, but the ferruginous and common pochard has expanded their breeding grounds, and even to the core areas of Baer's pochard's, which makes the hypothesis possible. The research on its gut microbiota showed that the richest microorganism phyla of Baer's pochard are Bacillota, Pseudomonadota and Bacteroidota, which were consistent with those of the domestic goose, duck and chicken. The gut microbiota in diarrheic Baer's pochard is low in diversity, and the species were also significantly different from healthy individuals. Most species in reduced numbers are thought to be intestinal beneficial bacteria. Threats and protection Baer's pochard was once a common species in its range, but is now very rare.