William L. Finley using a ladder to climb to the top of a saguaro cactus to investigate a bird’s nest.

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.

A red-tailed hawk perched in a nest on a saguaro cactus.

Three red-tailed hawks perched in a nest on a saguaro cactus.

Three red-tailed hawks perched in a nest on a saguaro cactus.

A saguaro cactus with a bird nest in the top.

Cholla cactus with Catalina Mountains in the background. A nest is visible in bush.