Why Are Bluebirds Blue?

It's a trick of the light!

What is the name of the bird that looks like a bluebird? - Quora

Western Bluebirds on My Street – Foothills Clusters Wildlife

Eastern Bluebird (Sialia sialis)

All About Bluebirds

Bluebirds are back from the brink thanks to human interventions

Why are some bluebirds bluer than others? - Avian Report

Why Are Some Feathers Blue?, Science

Eastern Bluebirds - New Hope Audubon Society

Blue Birds - Are They True? - Bird Buddy Blog

Eastern Bluebird (Sialia sialis)

Why are bluebirds blue? - Nature Alberta