Birds can accurately navigate over hundreds to thousands of kilometres, and use celestial
and magnetic compass senses to orient their flight. How birds determine their location in
order to select the correct homeward bearing (map sense) remains controversial, and has
been attributed to their olfactory 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. Atmospheric processes affecting the
infrasonic map cues can explain perplexing experimental results from pigeon releases.
Moreover, four recent disrupted pigeon races in Europe and the north-eastern USA
intersected infrasonic shock waves from the Concorde supersonic transport. Having an
acoustic map might also allow clock-shifted birds to test their homeward progress and select
between their magnetic and solar compasses.
Infrasound and the Avian Navigational Map
