Outside Yuma, Arizona—not far from the Mexican border—my husband and I got lucky in finding a dispersed camping spot along the Senator Wash lake front. The reservoir water level had receded, leaving extra beach space, and I spent hours soaking in the view while walking a swath of dried lakebed.

Strangely, the mud had dried into zillions of baseball size pockmarks. I wondered if some special property of the soil caused it to dry with depressions. Had some aquatic species somehow excavated indentations? Too small for people tracks…dog, coyote, bobcat, deer? Maybe, but probably too small, and anyway, that many dents would have required a multitude.
Following a dried inlet away from the lake, I discovered inviting green havens hidden in the surrounding trees and brambles. This was February in deep desert country, and even glimpses of green brought joy. Further up the inlet, I found a track.

The clue that explained all.  Thirsty wild donkeys.

Turn of the century prospectors and miners generally used donkeys–AKA Rocky Mountain Canaries–to carry supplies.  When the donkeys were no longer needed, many were freed to survive as best they could.  Their offspring continue to thrive in often hostile terrain.

Another clue!

Next morning, the beach had shrunk. Imperial Dam had apparently been allocated more water. My out-of-the-way walking swath was flooded, softening up to receive another round of hoof imprints.