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This head-hidden bird suddenly sailing by gives one little time to get a bead on the beast’s identification. However, the mental image one retains after it is gone presents a couple pale areas, with one in the outer primaries and the other on the tail and, possibly, including the upper-tail coverts. Surely, one might think, a sizable bird with an odd mix of brown and black upperparts plumage and those distinctive pale patches gliding on slightly arched wings ought to be distinctive. I would agree.

What species is represented here?