Which mark is particularly distinctive on the Peregrine Falcon?

The distinctive mark of the Peregrine Falcon is the face bar, also known as the "moustache mark." This feature consists of a dark, horizontal stripe that runs across the falcon's face, contrasting sharply with its lighter facial coloration. The face bar is a key identifying characteristic that helps distinguish the Peregrine Falcon from other similar species. It plays a significant role in the bird's overall appearance and can be a reliable field mark for bird watchers and falconers alike.

In terms of the other options, while the breast bands are present in some falcon species, they are not as distinctive or exclusive to the Peregrine Falcon. Colorful tail feathers could describe various raptors, but they are not unique to the Peregrine. Wing patterns also exist across different species but lack the specificity and recognition that the face bar provides for identifying this particular falcon.