A poignant tale of adoption

Our story begins with a baby turtle standing at the bottom of a large tree and with a weary sigh, he begins to climb. About an hour later, he reaches a very high branch and walks along it to the end. He turns and spreads all four stubby legs and launches himself off the branch, flapping his feet wildly. On landing at the bottom in a pile of soft dead leaves, he shakes himself off, walks back to the trunk of the tree and with a sigh he starts to climb.
About an hour later, he again reaches the very high branch, walks along it, turns, spreads his legs and flings himself off the branch. Again, he lands on the bottom, shakes himself off, goes to the trunk of the tree, sighs and begins climbing.
Watching these pathetic proceedings from the end of the branch are two little birds. Mummy bird turns to Daddy bird and says, "Don't you think it's time we told Junior he was adopted?"