There’s nothing fancy about the boat-tailed grackle, a lanky relative of the blackbird and the oriole. Grackles populate the coast from Texas to Long Island, and are the goats of the bird kingdom — they will eat just about anything they find, from small crustaceans to scavenged dumpster fare.
But if you have a hankering to try drawing an iridescent surface, the boat-tailed grackle is your ideal model. A sheen of shimmering blue, purple or copper play over these birds in sunlight. Microscopic structures on their feathers break light apart, like a prism, and create a reflected rainbow.
(This fellow was drawn with Prismacolor colored pencils on medium-weight Bristol vellum. He was the demonstration drawing for my work-at-your-own pace online course, Birds in Colored Pencil. )
valwebb.com 
I’m having a grand, grand time learning about black birds. Thank you.
Wow, I really like that. I’m curious to try to achieve that kind of effect with wooden pencils.
Terrific!
Really beautiful work, you captured him perfectly! Karen