Different sized birds follow the same rules when flying in flocks, likely to save energy.
Full article: When birds of the same feather fly together: the impact of achievement goal compatibility in collaborative learning
Get to Know the Super Smart Corvid Bird Family - Birds and Blooms
Understanding ADHD: Why ADD Family and Friends Stick Together
The Bizarre Bird That's Breaking the Tree of Life
How Flight Feathers Evolved: Study of Chickens, Ostriches, Penguins, Ducks and Eagles
File:Birds of a Feather Flock Together (Homer Davenport).jpg - Wikimedia Commons
Birds of a Feather Flock Together by David Lilly - The Canadian Nature Photographer
How Mozart Changed My Mind About America's Most Hated Bird ‹ Literary Hub
Birds of a Feather Flock Together by David Lilly - The Canadian Nature Photographer
Birds of a feather flock together, but only in similar climates
Photoshop Magic Turns Flocks Of Birds Into Perfect Patterns, 46% OFF
Feathers Together (Feeling Friends) by Caron Levis