Thanks to the expert ear and owl calls of Luis, my birding guide in San Pancho, we found this adorable bundle with delicately arched eyebrows, AKA a Ferruginous Pygmy Owl.
Ferruginous: from Latin: ferrgin-, iron rust, iron-rust color.
Pygmy: it's damn small--with a body about the size of a man's balled fist.
Seeing this owl and capturing its face was particularly satisfying as I'd briefly seen its relative, the Northern Pygmy Owl, in Arizona last fall. It was similarly perched above me, about 20' up, in an anonymous, indistinct little brown ball which flew away before I could photograph it well. So being able to look into the face of a Ferruginous Pygmy Owl makes me feel the circle is somewhat closed now.