From Causes of Insomnia: "Hiking Alone"

Stanton feels vigorous. Healthy. Hydrated. No aches, no pains. He feared his knee might give him a little trouble – the metal pin in it occasionally sticks – but so far the joint has felt nothing but loose. He’s limber all over. He feels alive, the way the sweat rolls down his back. And yet…

It makes him uneasy, there being so many vultures overhead.