Interestingly enough birds are the one group that systemically destroys the sentience tests. One test, the Mirror Self Recognition test was thought to only be

Interestingly enough birds are the one group that systemically destroys the sentience tests. One test, the Mirror Self Recognition test was thought to only be accomplished by humans and the great apes, even monkeys aren't capable (in the traditional sense). However the humble pigeon passes, and not an occasional get lucky pass, but pigeons just nail the test. Tool use was one of the very classical 'gateways' to sentience argued for humans. Except there appear to be far more bird species than mammal species that regularly use tools. Further than this, Herring Gulls are noted for tool-use hunting by using pieces of bread to hunt goldfish - which essentially one-ups all other known tool users. Ravens are one of the few species who actually make the toys they play with. IE they don't find a stick and play, but will break twigs off of trees and brushes with the intent of using it to play with others.