"So I thought, let's pretend the sky's the limit and I can train them to do whatever I want," Logan said. "I started by pointing at the one I wanted and continuing to point until he or she flew out. I got to the point where I could stand outside the aviary and point at the one I wanted and it would fly out while the other birds stayed put."
Two birds in particular 007 and Kitty became so well trained that Logan had only to call them by name and they'd fly into the testing room.
The testing room contained an apparatus consisting of two beakers of water, the same height, but one wide and the other narrow. The diameters of the lids were adjusted to be the same on each beaker. "The question is, can they distinguish between water volumes?" Logan said. "Do they understand that dropping a stone into a narrow tube will raise the water level more?" In a previous experiment by Sarah Jelbert and colleagues at the University of Auckland, the birds had not preferred the narrow tube. However, in that study, the crows were given 12 stones to drop in one or the other of the beakers, giving them enough to be successful with either one.
"When we gave them only four objects, they could succeed only in one tube the narrower one, because the water level would never get high enough in the wider tube; they were dropping all or most of the objects into the functional tube and getting the food reward," Logan explained. "It wasn't just that they preferred this tube, they appeared to know it was more functional."
However, she noted, we still don't know exactly how the crows think when solving this task. They may be imagining the effect of each stone drop before they do it, or they may be using some other
|Contact: Andrea Estrada|
University of California - Santa Barbara