Birds in flight coordinate their movements instantly

Researchers don't know how they do it, but the birds are very efficient at it.

An unnecessarily drawn-out analysis of bird flight for animation

Thousands of starlings fly together to make an enormous bird

A BIRD'S FLIGHT

What Is A Group Of Birds Flying Together Called? - Fauna Advice

Birds of a feather … track seven neighbors to flock together

A biologist explains the science of murmurations - Big Think

How do birds that fly in a flock know which direction to go? - Quora

Why Do Flocks of Birds Swoop and Swirl Together in the Sky?

Through Hawks' Eyes: Synthetically Reconstructing the Visual Field

Nature curiosity: Why do some birds fly in a V formation?