If one saw people running after a find, after a lame deer, or after young pigeons that cannot yet fly, and said, “My field has acquired it for me,” - it has indeed acquired it for him. If the deer was running normally, or if the pigeons were flying, and he said, “My field has acquired it for me,” - he has said nothing.

This method of acquisition is called “courtyard.”  The owner doesn't have to declare his intention – it is only stated to emphasize the second case in the ruling. He does have to stand next to his field, making it comparable to a courtyard.