Elf owl looking out of nest hole in giant cactus. Image note: large size, best plate.

Two elf owls in cactus. Image note: side view.

Two elf owls perched in cholla cactus. Image note: side view.

Herbert Brown standing at the top of a ladder examining an elf owl nest in the top of a giant cactus. Horse and buggy in the background.

Herbert Brown standing at the top of a ladder examining an elf owl nest in the top of a giant cactus. Horse and buggy in the background.

A great horned owl perched in its nest on a saguaro cactus.

An unidentified man photographing a great horned owl perched in its nest on a saguaro cactus.

An unidentified man with a camera on a tripod photographing a red-tailed hawk perched in a nest on a saguaro cactus.

An unidentified man with a camera on a tripod photographing a red-tailed hawk perched in a nest on a saguaro cactus.

An unidentified man with a camera on a tripod photographing a red-tailed hawk perched in a nest on a saguaro cactus.