the zoo is always fun!!

When we went to the Baltimore Zoo last week, we saw a Guinea bird pecking the head and then pulling the hair out of the Wart Hog in the cage next to him. Was that because the bird was trying to give the hog a makeover? Or was the bird appalled by his shear ugliness? Where did the term "birdbrain" come from? I am afraid of birds and with good reason as you can plainly see.