When compared to its close relatives, what general characteristic makes identifying the Mourning Warbler challenging?

Answer

It is a skulker of the dense understory

The bird earns its reputation as a skulker of the dense understory, requiring patience, a sharp ear, and an appreciation for subtle plumage cues because it stays low and prefers solitude in thick cover.

When compared to its close relatives, what general characteristic makes identifying the Mourning Warbler challenging?
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