Bird Coloration

Appearing on my bird feeder today,
at least six species, seven, possibly ,
the scientific title of the nuthatch, known?
black-capped chickadee, though similar, no kin.

Bright cardinal, by color aptly named,
though spouse an olive-hued caricature,
So bluebird spouse is gray and beige, and why?
No predator will likely spot the nest.

Woodpecker, downy, only a red spot,
among its black and white striped, wedged plumage,
would that distinction disinterest hunt,
and leave the small un-red-specked bird in peace?

Gold finch, purple finch seem to follow rule,
dull female hue of olive brown, not gold,
or red on head and shoulders nearly nil,
while colorful counterparts attract the eye.

Black bird or grackle, though their color dark,
follow pattern with irridescent male,
dull brown-black the spouse's nondescript plumage ,
so safety over beauty wins the day.