Ferruginous duck / Moorente (Aythya nyroca)
Wikipedia eBird Vogelwarte BirdLife ZH ornitho.ch Xeno-Canto BirdID NABUMoorente und Reiherente. 2021-03-07 12:08:04 Rapperswil
Exposure 1/1600
Classification: Genus Aythya (Aythya); Tribe Diving ducks (Aythyini); Subfamily Dabbling ducks plus extinct (Anatinae); Family Waterfowl (Anatidae)
Woody brown (ferruginous means rust-red), black and white with a gray bill. Butt is white, but also a part of the belly not seen when it's in water. Tall head reminds me of a Kolbenente/Red-crested pochard, but is pure brown.
Etymology:

Calls:

Physical details: length=38-42 cm, wingspan=63-67 cm, weight=450-700 g
Habitats: River and lake Only documented observation: 2021-03-07