Before revision: These crows were observed to modify the ribs of palm leaves by nibbling the ends to resemble a hook, and proceeded to use these tool to reach prey and food in previously inaccessible areas, such as small cracks within trees.
After revision: These crows were observed to modify the ribs of palm leaves by nibbling the ends to resemble a hook, and proceeded to use these tools to reach prey and food in previously inaccessible areas, such as small cracks within trees.