(noun) The area on the upperside of a bird's body between the uppertail coverts and back, or the part of the back closest to the tail, typically counted as part of the upperparts of a bird. While the rump may not be distinctive in many species, some birds have contrasting patches of color on the rump that can be used for identification, such as the yellow-rumped warbler. Depending on the size of the bird and how its wings are held, the rump may be visible only in flight, if the folded wings cover the rump, or it may be visible while the bird is perched.
To use a bird's rump for identification, check the rump carefully for colors or markings that contrast to the surrounding plumage. Also note whether or not the rump is visible while the bird is flying or perched, and whether or not it matches the color of the undertail coverts.
Photo – Yellow-Rumped Warbler © devra