"Zombie Chickens from Mars" explained

For some years during college and afterward, I worked with a philosophy author doing editing work and literature research for her books. She has two grandchildren and one day one of them drew a few artworks for me, including the masterpiece "Zombie Chickens from Mars."

So just what is going on in this picture? Well, to paraphrase what the artist explained to me, Earth is OVERRUN with zombie chickens from Mars that look almost exactly like normal chickens except they have bloodshot eyes and green slime coming out of their mouths (see the crazed, rabid zombie chicken on the right?). In this picture, a normal chicken is fleeing from a zombie chicken. He crosses the road to escape, but instead he gets hit by a car. How sad is that?