Infrasound and the avian navigational map

Birds can accurately navigate over hundreds to thousands of kilometres, and use celestial and magnetic compass senses to orient their flight. How bird s determine their location in order to select the correct homeward bearing (map sense) remains controversial, and has been attributed to their olfacto ry or magnetic senses. Pigeons can hear infrasound down to 0.05 Hz, and an acoustic avian map is proposed consisting of infrasonic cues radiated from steep-sided topographic features. The source of these infrasonic signals is microseisms continuously generated by interfering oceanic waves. Atmospher ic processes affecting the infrasonic map cues can explain perplexing exper imental results from pigeon releases. Moreover, four recent disrupted pigeo n races in Europe and the north-eastern USA intersected infrasonic shock wa ves from the Concorde supersonic transport. Having an acoustic map might al so allow clock-shifted birds to test their homeward progress and select bet ween their magnetic and solar compasses.