Working with captured wild crows, Russell Gray and his team from the University of Auckland in New Zealand hid a treat in a box so that a crow could only extract it with the help of a long stick. This kind of task is easy for the tool-using crows.The seventh crow has been held back a year, despite his parents' wishes.
But then the researchers added a twist by placing the long stick in a cage, out of the crows' reach. No problem: the birds used a second, shorter stick, to get the first one, then took it back to the box to get the food.
"Six out of seven crows tried straight away to use the short stick to get to the long tool. There was no trial and error," says Gray.
Update: Chris of Mixing Memory notes,
Recognizing that the long stick is sufficient, but the short one isn't, when looking at the placement of the food, and then understanding that the short stick is sufficient to retrieve the long stick is pretty impressive. I'm not sure it requires analogical reasoning -- association might be sufficient -- but I suspect that future studies will sort all of that out. However they're doing it, it's clear that crows are pretty damn smart.