Cuckoo Birds Are Jerks 

Apparently, cuckoos lay eggs in other birds’ nests, and those other birds are tricked into rearing the cuckoos. That’s certainly a jerk thing to do, but have a look at the pictures:

Cuckoo baby on the left, warbler on the right
“Feed me!”

If you’re feeding a bird five times your size who looks nothing like you, at least some of the blame has to lie with you.