Pro inaturalist rád fotím celé rodinky. Je tak uchováno datum, místo, počet mladých a z fotky se dá odhadnout věk.
For inaturalist, I like to photograph whole families. The date, the place, the number of young are preserved, and the age can be estimated from the photo.
https://www.inaturalist.org/observations/32352607
https://www.inaturalist.org/taxa/7045-Aythya-ferina
23.7.2019 South Bohemia, Czech republic