This is the prey of a heron. Part of the snakes were N. natrix, and others - N. tessellata. The other observation is here: https://www.inaturalist.org/observations/165481572
In the ocean between some rocks.
Natrix tessellata (Laurenti, 1768)
[Colubridae]
Ispra (Lombardia), 200m
first snake I see in zurich!
obs Massimo Vettorazzi