The Orientational and Navigational Basis of Homing in Birds

Infrasound and the Avian Navigational Map

“…Infrasound waves can travel thousands of kilometres in the atmosphere with little attenuation, a distance comparable to the farthest range of pigeon homing. Significant levels of infrasound can be radiated from topographic features (Cook, 1971;Young and Greene, 1982) at frequencies within the hearing range of the pigeon (Kreithen and Quine, 1979), and atmospheric conditions affecting the infrasonic map cues can explain site-release biases and their more mysterious dayto-day variations (Keeton, 1974). Also, microbaroms in the atmosphere could interfere with avian map cues of similar frequency, adversely affecting homing performance (Gronau and Schmidt-Koenig, 1970).…”

“…There is one exception: on 13 August 1969, birds from Cornell and Fredonia to the west were released at Jersey Hill. The Cornell birds vanished in a tight group to the northeast and the Fredonia birds vanished well-oriented to the west, and all the birds returned to their lofts that day (Keeton, 1974).…”

Foreword to papers on magnetic sensitivity in birds

“…The total intensity of the earth's field varies geographically between about 0.25 and 0.65 G, and in temperate latitudes the horizontal component is on the order of 0.25 G. The earth's field varies in time, with short-term variations in magnetic storms commonly on the order of a few hundred gamma, where I gamma = 11100,000 G. The earth's field also varies over short distances due to deposits of iron, and these variations are also on the order of 1/1,000 of the earth's field. Magnetic storms and magnetic anomalies have been reported to affect the orientation of birds, as reviewed by Able (1980), Gould (1985), and Keeton (1974). These reported effects imply sensitivity not only to the earth's overall field of roughly 0.5 G but to variations over time and space of less than 0.1 %.…”

The Hippocampus as a Cognitive Map

“…Recent work has concentrated on the features of the compass (e.g. Keeton 1974). Thus far there are three different mechanisms by which birds have been shown to calculate compass direction; these involve the use of the sun, the stars, and magnetic fields.…”