We walked out of the desert and hit a road. Next to the road was a tree, and in the tree hung a wolf. It had been strung up by its heels. What little fur remained parted this way and that as the wolf rotated slowly in the hot wind.

“Wolves are threatened in Saudi Arabia,” says Ahmed al Boug, the General Director of the National Wildlife Research Center, the scientific arm of the Saudi Wildlife Authority. “I myself, over more than 20 years of field work, have seen about 50 wolves hanging in trees. Shepherds shoot them and put them there. Nobody really knows how many are left.”

Al Boug says that protected zones are the best hope for Arabia’s last wolves. The kingdom already has 15 nature wildlife preserves. Together they cover more than 30,000 square miles: 4 percent of the nation’s surface. Al Boug says that more reserves, for all sorts of animals, not just wolves, are in preparation and will double that area. “There are good things happening,” Al Boug says. “But enforcement needs more work.”

Presumably, local herders suspend wolves in trees to warn off the dead wolf’s kin.

This practice ascribes supernatural intelligence to wolves. It’s probably merited. Bedouin folklore is a filigree of wolf tales, odes to the human-ness of this animal that may soon be gone, much as the way the Arabian leopard is almost gone. (The number of leopards remaining in Saudi Arabia is perhaps 40.)

We walked on.

We made camp next to a concrete well under a tall, womanly, smooth-branched sahur tree. The moon shone like a wolf’s eye caught in the spotlight of the sun. I could hardly stay conscious for our canned dinner.

When the first humans roamed across the unknown world they experienced days imaginable to us now. Among the things we can never know—that is, we can describe it but never feel it—was the fact that we were walking food. Saber-toothed tigers, massive cave bears, archaic lions, and scores of other powerful animals ate us. This state of awareness, of being prey, comes down to us through the millenniums, faintly echoing like a distant scream in a canyon, as metaphysics. As dreams. As a muscle reflex. As religion. An empty alertness. We are the haunted superpredator.

I was watching our two cargo camels, Fares and Seema, graze under the moonlight when I heard them. The camels looked up in unison. I looked up. It came from the Hejaz mountains, a cardiogram of sharp peaks, blued in moon shadow. Two wolves called to each other once, and not again.