When it comes to intelligence, scientists have long considered birds to be intelligent, but there is one bird that has always puzzled scientists and that is the crow.
Scientists have discovered that crows have the ability to build things, store them, take care of tools, and even enjoy playing.
Now scientists have recently discovered that crows are also extremely vindictive and hold grudges for long periods of time. They never forget those who try to harm them.
John Marzulf, a professor at the University of Washington in the US, began his study by capturing and imprisoning seven crows using a scary mask and releasing them after some time. Before releasing them, they put identification tags on the legs of the birds.
Some time later Professor Marzulf and his team wore the same masks and circled outside the university campus, feeding the crows and recording their reactions.
They found that 47 out of 53 crows showed aggressive behavior, but later when the crows were approached with the mask off and the feeding process repeated, the behavior was different. Which proved that crows have the ability to remember shapes.
