>>9819242>Why is that one spot on the head the only thing in color?Because that's how the character looked in the short he came from. Silva didn't create the design, it's a Fan's Choice vote. realistically, the single bright splotches of color against an otherwise dark/monochromatic color scheme is something you see in modern male birds - it's there to attract females. His specific color scheme looks to be based off of a Woodpecker, see pic related.
https://www.youtube.com/watch?v=uQJWcrjC_OY 