All birds have nostrils, or nares, located at the base of the bill through which the bird breathes. Within the skull is a pair of chambers that consist of maze-like folds (called concha) that both warm and clean the air before it enters the lungs. The folds also have nerves that allow the bird to smell.
How well birds can smell is an on-going debate among ornithologists. What is certain is that some species have better-developed sensory organs than others, and the sense of smell has many uses.
The family of seabirds called "tubenoses", which includes albatrosses, fulmars, petrels and shearwaters, have incredibly large nares and very well developed olfactory centres (the part of the brain that deals with the sense of smell).
For example, fulmars can smell fish oils from up to 25 kilometres (15 miles) downwind, so when these oils form a slick on the sea surface as a result predatory fish and mammals attacking shoals of fish and squid underwater, the fulmar are quickly at the scene to forage for food. Other sea birds can smell a pheromone that fish give off when stressed.
In addition, some petrels and shearwaters forage for food at night and, at least in part, return to their burrow by smelling the odours from it.
Most garden birds, such as thrushes, finches and tits, however, do not have such well-developed senses of smell. There is still evidence, though, that some species, such as pigeons and doves, rely partly on odours to navigate, and others use their sense of smell for still different purposes:
Thus, it seems birds do have a sense of smell, albeit sometimes used for quite different reasons to our own.