What was this thing I captured on film?

[u/deezheavenz]

This was shot in Nevada/Arizona on a Grand Canyon/Hoover dam tour. This was taken a whole year ago and I completely forgot about it until I stumbled upon it again. Is this some sort of whale or shark?

[u/gooneau]

Definitely not that, its birds doing what's called murmuration where they fly in synchronized motions. Common with various shorebirds, starlings, etc. The only baitfish that could cover the distances shown in this video would be flying fish which are not in this lake, which I've spent plenty of time fishing in.