Female Kestrel Identification

I've been watching the Peregrine Fund's kestrel cam and have gotten a good look at the feathers and coloring of the females. I snapped some pictures of them for future reference.

Of the two bending down, Haggard on the left, Passage on the right.

Haggard tail and feathers.

Passage tail and feathers.

Which goes to show that the old rule of thumb that "if the last dark band on the female tail feathers is twice the size of the others then it's a haggard" is not a reliable reference. Comparing the two above I see that the bands on the back and secondaries seem thicker on the passage than on the haggard which gives it an overall darker appearance in color. While observing the nest in better lighting conditions I could see that the haggard was a more rust color while the passage birds were more toward brown than rust. It also seems that the trailing edge of the primaries are a more pronounced white on the passage and more tan or thinner on the haggard. Given, these birds are from the Boise, Idaho area and may not be similar to what I may see at home. I'm tempted to set up a nest box nearby and get a look for myself at the local birds.