Some bird species are rather specialised in taking only a particular type of food (e.g., seed-eating finches), but most take in principal a wide variety of food items. This wide range is apparently due to an initial responsiveness to a variety of food objects (stimuli), but the effective stimuli are later narrowed by learning (trial and error of edibility) which is determined by the food availability in the environment and the possible repertoire of typical feeding habits of the species. E.g. tits, but few other species, learn to open milk bottles because they have the innate motor (moving) patterns necessary to do so; and the size of seeds taken by finches is determined in large part by the size of the bill. Parental example and local experience (cumulated learning) are also important in this respect, the latter especially in flocking species. Some species change their diet with the seasons, which is largely determined by climatic conditions and migration. The change in diet often coincides with the onset of breeding. The ability to use the foot in conjunction with the bill (e.g. Magpies) enables the taking of food otherwise unavailable (e.g. the feeding of Goldfinches on thistle heads). It is often a characteristic (innate) of the species, but learning brings it into perfection. See also: feeding.

Alternative form for food : foods.