The bird navigation theory as presented implies an organ or organs in the bird's physiology which are sensitive to the effect of its motion through the vertical component of the earth's magnetic field and to the effort exerted to overcome the coriolis force, due to the earth's rotation. Both these influences involve a set of lines which together form a navigational gridwork. By correlating its instantaneous land speed with the two above effects, a bird can fly to its home which is a unique point in this gridwork, or to related companion points existing in the gridwork at positions other than its home. Experimentation with homing pigeons between the home and spurious home points (conjugate or companion points) has yielded data which supports the theory.
REFERENCES
1.
Frederick C. Lincoln, The Migration of American Birds (Doubleday, Doran and Company, Inc., Garden City, New York, 1936).
2.
J. L. Peters, Check‐list of Birds of the World (Harvard University Press, Cambridge, Massachusetts, 1931), Vol. 1 or 2;
ibid., Vol. 2, 1937;
ibid., Vol. 3, 1940;
ibid., Vol. 4.
3.
A.
Thauzies
, “Apropos d’une theorie sur l’orientation du pigeon voyageur
,” Rev. Sci. (series 5)
3
, 270
(1905
);4.
Dr. W. H.
Thorpe
and D. H.
Wilkinson
, “Ising’s theory of bird orientation
,” Nature
, December 21 (1946
).Also,
G.
Ising
, “The physical possibility of a biological sense of orientation based on the rotation of the earth
,” Ark. Math. Astrophys.
32A
, No. 4
(1946
).5.
Experiments With Homing Pigeons’ Sensitivity to Radio Frequency Waves, conducted by 285th Signal Pigeon Company, March 1945.
6.
F. J. Sauerteig, “Indianapolis,” Am. Racing Pigeon News, Nov. 1942, p. 1.
7.
See reports to the U.S. Army Signal Corps listed in the Foreword.
8.
This effect may be the same phenomenon as the so‐called “electromagnetic effect,” it will subsequently be referred to as such for the sake of brevity.
9.
World values of H may be obtained from map No. 1702, “The vertical intensity of the earth’s magnetic force,” published by the Hydrographic Office, Washington, D.C. Values for the United States of America from Booklet and Serial number 602, as previously indicated.
10.
Having been in full flight around loft, the bird returns and enters it. During his first free flight outdoors even though raised on the spot, it is easily frightened off in a panic, and may fail to take visual account of its surroundings. On a second release it is practically certain to return.
11.
Its location was shifted 200 feet each day for training flights of the birds, and never returned to a previous location.
12.
Short distance flights in which guidance could always be had by means of familiar landmarks.
13.
G.
Reynaud
, “The laws of orientation among animals
,” Smith. Inst. Ann. Report of Board of Directors, p. 481, (translated from Rev. des Deux Mondes
146
) 380
(1898
),14.
Of the remaining fifty of the original three hundred, half were youngsters, the others yearlings. The twenty‐five yearlings were released at Culbertson in a group most of which took up residence on the spot. The twenty‐five youngsters were retained for “navigation” training at State College, Pennsylvania, for later experimentation.
15.
See explanation in Glossary appended to Table IV. Explains training which they must have to home successfully from a distance. It therefore seems evident, whereas they may inherit the ability to navigate, that they must first have specialized and adequate training in order to accomplish it.
16.
F. J. Sauerteig, “Indianapolis,” Am. Racing Pigeon News (November 1942).
17.
Ralph Gundlach, “Field study of homing pigeons;” Lucian H. Warmer, “The present status of the problems of orientation and homing by birds;” “Homing pigeons a puzzle to science,” Am. Weekly (June 3, 1945).
18.
F. C. Lincoln, The Migration of American Birds, p. 54.
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1947
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