Many bird species gather in large numbers. I often hear a chorus of sparrows when I pass by their favorite trees or hedges.
Copious gathering of cattle egrets (Tarangire National Park, Tanzania): along the lakeshore and even in the trees!
Copious gathering of flamingos (Amsterdam zoo):
Posted for photo challenges RDP 9/17/18: Copious and Becky’s Month of Squares: In the Pink.
Wanderlust & Wonderment 
Those Egrets are amazing. I’ve not seen that many ever, and we see lots in Portugal. Loving the fact too it is flamingoes that are making you square 🙂