Two Vampire Bats

One evening two vampire bats were hanging out in their cave. One said, "Man, I'm starving! I need to get some blood!" And he flew out of the cave. 

He returned about three hours later with blood dripping from his mouth. 

"Where'd you get the blood?" the other bat asked. 

"Well, you fly out of the cave, and you see the first tree on the left?" 

"Yes," the other bat replied. 

"Well, I didn't."