Because of the polluted water in the nearby area the crows have mutated. The environment filled with radiation caused the birds to become aggressive. So they wreak their anger upon nearby scarecrow, who frightened them. Scarecrow tries to escape, but it is stuck in the mud. The rest is your own imagination :)
This image was done for strange behaviour challange on cgtalk. I used max, maya, zbrush and photoshop.