HISTORICAL AND EXPERIMENTAL STUDY OF HOMING. 23 



observations at his cote in Perigueux. He gives little material which is 

 serviceable in solving the problem of homing. One statement he makes which 

 is useful is that the birds rarely fly higher than 300 meters; the average 

 height is 150 meters. If a mountain range causes them to fly high in passing 

 they immediately fly down again and stay near the surface of the earth. 

 The only really positive evidence which Thauzies advances in support of the 

 theory comes from the parallel records which he has kept of disturbances in 

 flight and of disturbances in terrestrial magnetism. We summarize the facts 

 from two cases: 



On August 18, 1907, the Soci6t^ Colombophile, of which I am a member (L'Hirondelle 

 de Perigueux), released at Orleans (320 km.) at G"" 30" a. m., on a bright calm day with slow 

 south wind, 99 young pigeons which, up to that time, had given perfect satisfaction." ". . . 

 this journey, which we would have thought extremely slow if completed before mid-day, 

 was not completed by any bird before 2'' 43". Only 11 subjects came back before night, 

 the rest the following norning. It was so abnormal that we made inquiries of others. 

 We learned that most of the societies in these regions who had pigeons en route had been 

 as surprised as we ourselves were by the tardy home-coming of their birds. The year 

 preceding, on July 22, we had been victims of a yet more singular misadventure. Our 

 young pigeons released at Angouleme (65 km.) at 10 o'clock under an admirable sky, limpid 

 and without wind, required more than 3 hours to make the journey, which should demand 

 scarcely an hour. Many birds were even later than this and many were lost altogether. 

 On taking up the matter with the Astronomical Department we found that on July 22, 1906, 

 and on August 18, 1907, there were severe electrical storms. 



Thauzies's observations are incomplete because of the fact that there may 

 have been many just as violent electrical storms which produced no retarda- 

 tion in the flight of the birds. Until the test has been worked both ways, one 

 can not draw any conclusions, and even if an electrical disturbance did produce 

 a retardation of flight, this would not necessarily imply that the birds were 

 using terrestrial magnetism as a means of orientation. There are possibly 

 other phenomena connected with electrical disturbances which may have 

 produced the effect. The correlation, if it could be made, would be exceedingly 

 interesting.* 



EXPERIMENTAL EVIDENCE AGAINST THE REFLEX THEORIES. 



Exnerf has made the most careful experiments to be found in the literature 

 on the conditions which affect flight. If his results could be confirmed under 

 slightly better conditions they would certainly discredit both Reynaud's theory 

 and certain of the theories based on magnetic sensibility. He tried the 

 experiment of stimulating the birds with an electrical current during the for- 

 ward journey; anaesthetizing the bird, rotating it, etc. His experiments were 

 carried out near Vienna. Several experiments of the following kind were 

 made : birds were carried in a box arranged for the giving of electrical stimu- 

 lation; electrodes were placed upon the head in such a way that a current 

 could be made to pass through the semicircular canals, etc. 



Quer durch den Kopf geleitet, bewirkt ein galvanischer Strom bekanntUch bei Mensch 

 und Thier Schwindelgefiihle, das heisst die Empfindung einer Drehung oder Neigung, deren 



*The U. S. Weather Bureau at Washington has offered to cooperate with us in attempting such 

 correlations. It may be possible to warn an observer in advance of the possible approach of an 

 electrical storm (approach of sun-spots, etc.). It would seem feasible, with such a warning, to 

 ship the birds several hundred miles and then release them and note the returns. 



tExner, Sigmund: Negative Versuchsergebnisse iiber das Orientirungsvermogen der Brief- 

 tauben, Stizungsberichte der Kaiserlichen Akademie der Wissenschaftcn (Wieu), p. 318. 



