ITT ecological cycles/phenomina

I'm talking about the grand cycles like seasonal bird migration, butterfly migration, cicada emergence cycles, etc. The grand rhythms of nature that really give you a glimpse into how big an graceful this world is.

Wondering if Europe or asia has anything like these as I only know of these events in North and South america.
Any in particular you love. For me it's bird migration. I love seeing the high density swell of birds come back in the spring and thinking about how far they travelled.