It is similar and closely related to the ferruginous duck, and they were previously considered to be a single species; Baer's pochard is differentiated by its white flanks when floating on the water, as well as its longer, more rounded head and larger size.
The nest, built from sedges, reeds and other plants, is placed among emergent vegetation, usually in shallow water or on small islands or ridges.
Baer's pochard was first scientifically described in 1863 as Anas baeri by Gustav Radde in his book Reisen im Süden von Ost-Sibirien.
The epithet and English common name commemorate the Baltic German naturalist Karl Ernst von Baer.
[4] However, Chinese ornithologist Tso-hsin Cheng treated them as two distinct species, as they had breeding grounds which did not overlap, and he had seen no evidence of hybridisation.
[note 1][8] While the species was long thought to have arisen from eastern populations of the ferruginous duck, American ornithologist Paul Johnsgard says its behaviors suggest it may instead be more closely related to the hardhead.
[6] American ornithologist Bradley Curtis Livezey published a phylogenetic study based on morphological data in 1996, in which he proposed his view on the relationship among Tribe Aythyini.
[5] Two molecular phylogenetic studies on Anseriformes or Anatidae were published in 2000s, some mitochondrial genes were sequenced, but Baer's pochard was absent in both of them.
[12] The female Baer's pochard has a distinctly bright chestnut spot at the lore, which is absent in ferruginous duck.
[13] Baer's pochard traditionally bred in the Amur and Ussuri basins in Northeast China and the southeastern Russian Far East.
[note 2][1][20] Baer's pochard is a shy species, that inhabit open, slow-flowing lakes, swamps and ponds.
In migrating season, they form small groups of more than 10 or dozens of birds, flying at low altitudes in wedge-shaped formations.
[8][12] During winter, Baer's pochard sleeps during the day, leaves for unknown feeding sites with other ducks in the dusk, and returns before dawn.
[18] In traditional breeding grounds in northeastern China, Baer's pochard gathers in gaps in the ice before it completely thawed.
[12] While in Fuhe Wetland in Wuhan, Hubei, Baer's pochard gathers in large groups on the open lakes before breeding season.
[23] Baer's pochard's nest is circular cylindrical, located among emergent vegetation, usually in shallow water or on small islands or ridges.
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.
[18] Studies have shown that the nest survival rate[note 3] of Baer's pochards is about 14–45%, and each clutch may lose one to nine eggs.
[24] In Wuhan, Baer's pochard shares breeding sites with cotton teal, eastern spot-billed duck and mallard.
Some individuals showed mixed characteristics of common, ferruginous and Baer's pochards,[note 4] so they may be currently hybridising in the wild.
[26] 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.
[29] In 2022, media reports state that the first captive population in China was established in the Beijing Zoo, with totally 54 individuals.
[30] A study published in 2022 showed that most breeding sites (81.8%) and suitable habitats (94%) are not located in protected areas, and overlap with large cities.
Current protected areas may be less effective for the conservation under predicted global climate change, closely coordinated cross-border cooperation would be critical for Baer's pochard.