practicing in the woods (open)

I throw the knife at the target and it thuds right into the bulls eye. In the forest is way better than being surrounded by annoying, peppy kids at school. Here it is just me, my knives and the target. I am about to throw another knife, but just as I am throwing it I hear the crunching or twigs to my left and throw my knife at a tree near the sound. Hoping throwing the knife in their direction will scare them off, but I hear no more foot steps. I wonder who this person is and why they weren't scared by my knife.