Dark Phased.

[canvibe]

Steve, you are correct. However, age could be defined as a phase. Nonetheless, absolutely gorgeous bird.

Wouldn't an immature Harlan's be considered to be in an imature color phase, not only does the color of their tail feathers change, they usually get darker after their first molt.

Without determining that the hawk in the picture is not a Harlan's, it is incorrect to classify it as a Dark Morph.

Morphs must occupy the same habitat at the same time: this would exclude geographical species such as the Harlan's

The term Morph in reference to color variation makes no sense as the bird is not going to morph into something else.