e to achieve this (74). It is a simple and well-known fact that pigeons home; they do so almost regardless of what we may do to them. Therefore, natural and manipulated changes of the magnetic field have been shown to affect their homing behavior to a varying degree (Dorst 66). In the year 1974, Walcott and Green concluded that artificial fields applied to the pigeon’s head on the release sight, under overcast conditions, disrupt the bird’s ability to maintain a constant compass course. The artificial field in the order of strength of the earth’s magnetic field obviously upsets the bird’s magnetic compass, either by changing its objective north direction, or by field strengths above or below the appropriate level (71). In 1978, Kiepeenheuer proposed the inversion of the vertical or the horizontal magnetic field component during transport, results in a diverted or random orientation on release (Kiepenheuer). Aside from such effects, after severe manipulations of the magnetic field, much more subtle changes in magnetic field strengths in the order of one percent or even far less of the normal field have been demonstrated to affect the orientation of homing pigeons. Temporal fluctuations, as well as slight topographical changes, may result in a shift of the mean of vanishing bearings or even in random orientation of the pigeons on release. It appears improbable that such small variations in magnetic field strength have any influence on the magnetic compass of the bird, since, according to the results of Wiltschko dealing with robins and other small birds, the magnetic compass seems to be somewhat resistant to deficiencies of the field which is much larger than some of the ones in question. We therefore may have to conclude that the pigeon does not rely on some type of magnetic compass, but that, at least to some extent, its navigational abilities are influenced by very slight changes in the earth’s ma...