132 THE RIDDLE OF MIGRATION 



when they arrive here merely to starve to death 

 because winter still holds the country in its grip. 

 Could they exercise discretion they would not pro- 

 ceed. They might even turn back for a spell. But 

 in this they fail. Their activities are evidently 

 under physiological, not mental, control. 



Various species of seed-eaters other than the 

 junco have been used in small numbers in these 

 experiments. All have been species that do not 

 cross the equator and the results have been entirely 

 uniform. Each case, however, suffered from the 

 same objections as that of the juncos when it came 

 to getting information about them after liberation. 

 If the point was to be satisfactorily settled it was 

 imperative that some other species be used, one 

 familiar to the man in the street, not protected by 

 law, and able to fend for itself under winter condi- 

 tions in Alberta. An obvious solution could be 

 found in the crow, a good migrant, large and con- 

 spicuous, an omnivorous feeder, universally known. 

 The only objection, but rather a serious one, was 

 the supposed impossibility of trapping the species 

 during the summer months. In 1929, however, 

 thanks to the generosity of the directors of the 

 Bache and the Elizabeth Thompson Funds, money 

 was available for repeating the experiments on a 

 much bigger scale and the crow was decided on. 



