learning something new every day, the late 70s Pontiac Esprit sales and marketing effort to make the boring cars that didn't have the Trans Am bird and motor appealing enough to boost sales, was nothing but a color choice

Simply boring, but they chose to call these V6 Pontiacs, a Yellow Bird, Red Bird, and Sky Bird -  as no doubt the idea of naming a car a Blue Bird wasn't going to fly. Yes, I said that. 

Factually, Blue Bird was already trademarked, probably by the bus company https://cartype.com/pages/2016/pontiac_firebird_sky_bird__1978

photos from https://autopolis.wordpress.com/2013/03/30/1977-1980-pontiac-firebird-esprit-special-editions-birds-of-a-different-color/ but only because I learned of the Sky Bird from https://www.curbsideclassic.com/curbside-classics-american/curbside-classic-1977-pontiac-firebird-esprit-sky-bird-pretty-bird/

And Curbside found out about the Sky Bird from watching C.H.I.P.s, which had a dozen background cars, which were used in a lot of scenes, just to make it appear that the show wasn't filmed on back lots or empty streets a permit for filming would empty so no bystanders were involved, and one of the background cars was a Sky Bird.