{"fact":"Crows can even solve a tricky puzzle where one of the strings is broken, showing they can assess if a tool is actually useful.","context":"...one of the strings consisted of two fragments and was unsuitable for pulling the bait, showed that birds were in fact able to...to evaluate the value of the string, i.e., the logical structure of these tasks.","source":"M. S. Bagotskaya; A. A. Smirnova; Z. A. Zorina, Corvidae Can Understand Logical Structure in Baited String-Pulling Tasks, 10.1007/s11055-011-9529-z","index":436}