Page:American Journal of Psychology Volume 21.djvu/30

20

Cowbird was successful during the fifth and sixth trials, Fig. 7, but as a rule (and this obtained throughout this entire series) she waited until the Sparrow had made many attempts; then she came down and by a few pecks on one of the lower strings opened the door. For example in the sixteenth, eighteenth and nineteenth the Cowbird was successful, but the Sparrow made thirty-six, thirty-six and seventy- seven efforts respectively. Although he was the one to open the door in the trials just preceding these last, his great fright and wariness would not allow him to enter the box and eat the food. His habit was to seize the bits of food and carry them out to the floor of the larger cage and eat them there. It is interesting that my notes record the fact that the Sparrow seemed ill and had seemed so for a few days previously. The Cowbird then continued to open the door until the thirty- fourth and thirtyfifth tests. In the latter the Sparrow used his beak on the string, which was the Cowbird 's way of doing, Figs. 8 and 9. Some ten tests later the Sparrow came to strike with the bill the projecting upper edge of the door, a sort of effort which the Cowbird had been using for some time.

In the 48th, 49th, 51st and 52nd tests the Sparrow again used the bill to strike the first or second strings and he stood