| a gland opening on the back at the base of the tail in most birds that secretes an oily fluid used by the bird in preening its feathers. |
preen gland
in birds, an organ located on the back near the base of the tail. Paired or in two united halves, it is found in most birds. Absent in ostrich, emu, cassowary, bustard, frogmouth, and a few other birds, the oil gland is best-developed in aquatic species, notably petrels and pelicans, and in the osprey and oilbird.
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