Dippers are named for the up and down head movements they make whilst perched. They all have dense plumage with a large preen gland for waterproofing their feathers. Their eyes have well-developed focus muscles that can change the curvature of the lens to enhance underwater vision. Dippers have nasal flaps to prevent water entering their nostrils. Their blood has a high haemoglobin concentration, allowing a greater capacity to store oxygen than terrestrial birds, and allowing them to remain underwater for up to at least 30 seconds. Their prey consists primarily of invertebrates, small fish and fish eggs.Dippers’ calls are loud and high-pitched, being similar to calls made by other birds on fast rivers; the call frequencies lying within a narrow range of 4.0-6.5 kHz, well above the torrent noise frequency of <2 kHz.

Other dipper species include the Brown (C. pallasii), American (C. mexicanus), White-capped (C. leucocephalus) and Rufous-Throated (C. schulzi) dippers.

https://www.beautyofbirds.com/dippers.htm

https://en.wikipedia.org/wiki/dipper