Is 4 times better than a person with perfect vision.
Is twice as good as a person with perfect vision.
Is so poor that they rely more on hearing and vibrations to catch prey.
They have no feathers on top of their heads.
"balde" is an old English term meaning "white".
"baldd" is an Ojibway term meaning "quick mind".
The birds have no feathers on their feet.
Loss of habitat
Human harassment (shooting, poisoning)
DDT and other pesticides
Here's an interesting quiz for you.