https://www.myswitzerland.com/en-us/experiences/events/traditional-events-winter-fruehling/vogel-gryff-in-basel-bs/
Vogel Gryff in Basel (BS) | Switzerland Tourism
January 13, 20 or 27 If the date falls on a Sunday, the event is staged on the preceding Saturday
in baselvogelgryffbsswitzerland