Baer's pochard females of Baer's pochard and the ferruginous duck are quite similar, but that holds true for the females of almost all "Aythya" species. Eclipse males resemble females, but retain the white eye. Formerly classified as a vulnerable species by the IUCN, recent research shows that its numbers are decreasing more and more rapidly. It was consequently uplisted to endangered status in 2008. In 2012, it was further uplisted to critically endangered. Between 1987 and 2007, there were only eleven reports of groups of 100+ birds in mainland China. A recent census by World Wildlife Fund (WWF) China of Hubei province
Bird vocalization and prevent an energetically costly fight . In birds with song repertoires, individuals may share the same song type and use these song types for more complex communication. Some birds will respond to a shared song type with a song-type match (i.e. with the same song type). This may be an aggressive signal, however results are mixed. Birds may also interact using repertoire-matches, wherein a bird responds with a song type that is in its rival's repertoire but is not the song that it is currently singing. This may be a less aggressive act than song-type matching. Communication through bird