Just How Smart Are Ravens? Really, really smart:
The first experiment consisted of food hanging from a string below the bottom of the wire cage (pictured right, bigger). To get this treat, the bird had to reach down from a perch and grasp the string in its beak, pull up on the string, place the loop of string on the perch, step on this looped segment of string to prevent it from slipping down, then let go of the string and reach down again and repeat its actions until the morsel of food was within reach.They found that some adult birds would examine the situation for several minutes and then perform this multistep procedure in as little as 30 seconds without any trial and error — as if they knew exactly what they were doing. Because there was no opportunity for the birds to be confronted with a similar problem in the wild, the simplest explanation is that they were able to imagine the possibilities and to perform the appropriate behaviors. The authors also found that successfully performing this behavior required maturity: immature birds were unable to do it while year-old birds performed a variety of trials before they were able to succeed.
They can’t figure out a pulley though, where pulling down brings the food up. Read the whole article.