A bird feeder is provided with a containing structure including an internal space and at least one feeding opening on an outer surface of the containing structure and communicating with the internal space； a helical structure disposed on the outer surface of the containing structure in the form of a helix wherein pitch is defined as a distance from the crest of one thread of the helical structure to the next thereof； and at least one perch disposed on the outer surface of the containing structure and each disposed directly under the feeding opening.
