For more than 20 years, field ornithologist and consultant Dan Airola has been studying and helping manage a unique population of the Purple Martin (Progne subis) nesting under freeway bridges in Sacramento, California. This monograph (the first in what is intended to be a series from the Central Valley Bird Club, edited by Airola), brings together two decades of insight into balancing human-oriented infrastructure with the needs of a threatened bird species making a living in this bustling, constantly changing city. Historically nesting throughout the Central Valley, western martins never took to artificial nest boxes like their eastern cousins, though roof-nesting was noted by the earliest ornithologists visiting Sacramento in the 1800s. This phenomenon lasted into the 1970s when martins switched from building roofs to cement freeway bridges, coinciding with the arrival of European Starlings (Sturnus vulgaris), which seem physically unable to nest in the same vertical “weep holes” on the undersurfaces of bridges (p. 10–11).