The article discusses a study of a Mountain Bluebird nesting in a hole in the bank of an arroyo in Nambé, New Mexico. It describes the surrounding habitat which includes One-seed Juniper (Juniperus monosperma), Silver Sagebrush (Artemisia cana) and sparse Narrowleaf Cotton-wood (Populis angustifolia). Other similar holes were discovered in the banks of the arroyo, many occupied by the Rock Squirrel, Spotted Ground Squirrel (Spermophilus spilosoma) and the Desert Cottontail (Sylvilagus audubonii). The article reveals that the suitability of cliff or bank faces as habitat for nesting by the bluebird depends on both soil and scale.