This is a species of dry shrubby country. Typical habitat is in pinon-juniper woodland and riparian woodland in semi desert valleys. The animals roost in caves, crevices or abandoned buildings and other structures. They forage over water, along streams, over springs, among riparian or shoreline vegetation. In Colorado the Yuma Myotis apparently does not hibernate, however its winter haunts are unknown. They arrive in Colorado about April, and they become scarce in September.
Food consists mostly of moths, flies and beetles, but also includes leafhoppers, caddisflies, lacewings and craneflies. The animals forage near water and take many aquatic insects. They are efficient feeders and can fill their stomachs in 15 to 20 minutes. They forage in early evening, usually along the main channel of a stream.
In Colorado, where they are more widespread, breeding has not been studied much, however lactating females have been captured and a nursery colony was discovered in 1990 in the Colorado National Monument. Elsewhere, the animals are known to form nursery colonies of upwards of several thousand individuals in caves or attics. Apparently all adult females in a population breed. A single young is born late in the spring or early in the summer. Small breeding colonies have been discovered in the southeastern part of Colorado, but not elsewhere in Colorado. Males are solitary as the young are reared.