Roosters can't crow if they can't fully extend their necks.
28
The female pigeon cannot lay eggs if she is alone. In order for her ovaries to function, she must be able to see another pigeon.
65
Ants have tiny magnetic compasses in their antennae which help them navigate.
9
Crows living in some urban areas drop nuts into traffic to let the passing cars crush them, then they wait for the red lights to stop the traffic so they can grab and eat it.
17
There are more insects in one square mile of rural land than there are human beings in the world.
55
Sergeant Stubby was the only war dog to be promoted to sergeant through combat in WWI. He saved his regiment from surprise mustard gas attacks, found and comforted the wounded, and even once caught a German spy by the seat of his pants, holding him there until American Soldiers found him.
16
Cats have a weak sense of taste. They have only 473 tastebuds, humans have 9,000.
307