A trick of nature: Blue jays aren't really blue

Light trickery makes bird feathers blue but not red

Ohio's blue jay feathers aren't really blue, here's how it tricks your eyes

The Very Different Ways Cardinals and Blue Jays Get Their Hues - WSJ

Fun bird facts –

Nature News: Blue jays not as annoying as originally thought

You've Never Seen A Blue Feather. Would you check out this stunner. That…, by Nathan Finger, Creatures

Eugy Blue Jay 3D Puzzle, 26 Piece Eco-Friendly Educational Learning Puzzles for Kids 6+ : Toys & Games

The Philosopher's Stone is Blue. How Prussian Blue is Poised to Save…, by Courtney Abruzzo, Lessons from History