Filmed during the AMNH Arizona Expedition, 1940. Richard Archbold, AMNH research associate in mammalogy, organized this six-month-long expedition to collect all the elements for an Arizona group for the museum's Hall of North American Mammals. Animal behavior experiments were also conducted. Archbold was accompanied by A. L. Rand, AMNH research associate in ornithology, and photographer J. Lichtenfels. Expedition staff members are introduced in the film's opening sequence. Scenes of the desert environment, including such inhabitants as roadrunners, rabbits, and lizards, are shown as well as the expedition base camp in the foothills of the Rincon Mountains near Tucson. An experiment to determine whether birds can tell a predator from a motorized kite is conducted. A sequence filmed at night in Arizona's Saguaro National Monument includes the following animals: black-tailed jackrabbits, collared peccaries, mule or black-tailed deer, and great horned owls. A truck equipped with a motion picture camera and a battery of lights powered by a generator made night filming possible. There are day-time shots, also taken in the Saguaro National Monument, of a gila woodpecker and of cowboys rounding up, lassoing, and branding cattle. A long section focuses on people and activities at a rodeo in Tucson. An Apache ceremonial war dance is performed near a bonfire; the dancers wear ceremonial costumes. Flora seen during a collecting trip in Malino Canyon includes saguaro cactus, cholla cactus, prickly-pear cactus, mesquite, and other plants. The expedition team catches a ring-tailed cat and several species of rodent, including pack rats and ground squirrels; the animals are housed in wire cages at the base camp and their behavior is observed. A long sequence on birds follows, including redtailed hawks (with young in a nest in a saguaro cactus), great horned owls (young in nest), turkey vultures, white-winged doves, flickers, Gila woodpeckers, Gambel's quails, roadrunners, and vermilion flycatchers (close-ups of newly hatched young). Ducks and other water birds are seen on man-made reservoirs during spring migration. A curved-bill thrasher is weighed, measured, and used in a series of experiments (only one of which is filmed) conducted by Rand to determine whether the bird can recognize enemies; the enemy in the filmed experiment is a snake. The snake begins to coil itself around the bird, but Rand saves the bird from harm. Reptiles are the focus of the final sequence, which includes Colorado River toads, king snakes, longnosed snakes, rattlesnakes, a Gila monster (going after an egg), scaly lizards, and desert tortoises.