Many all black bird species have a gorgeous iridescence to them, when, and this is the important part, when they have a direct light source on blaring on them. The iridescence works on the very basic light principle, angle of incidence equals angle of reflection. This means in simple terms, the sun must be higher in the sky than we would normally like to see those colors in the black. It also means that if we use flash, in a hot shoe or in a flash bracket, this does not get the flash far enough away from the camera to get a big blaze of that color. You can simply think of it as requiring bad light to get those colors.
How do you make than a decent looking photograph if you have hot, constrastly light in order to get that iridescence in the black? There are a couple of things you can do and I share these photos of a Brewer’s Blackbird to illustrate them. I’m shooting across a creek with the D4s / 800mm w/TC-1.25x (1000mm) and that’s part of it, the narrow angle of view. That narrow angle of view permits you to move only an inch one way or another to get that angle of reflection. At the same time, select the best possible background for the nasty light. The creek is reflecting light which helps with the shadows. And I’m underexposing -1/3 more than normal to take the edge off the light. Combined, this makes the most of a bad scenario. Is this the only way to capture that iridescences? By no means, no! But it is the most common. When you’re looking for a subject when the light isn’t playing nice, just think bad light for color.