In this article, I examine Lost Children Archive, by Valeria Luiselli. I study the methods through which in the novel, sound becomes one of the main narrative tools to underscore the political, historical, and ecological facets of a complex biome that doubles as a border area. To this end, I focus on analyzing the projects carried out by two of the protagonists, which are an inventory of echoes and a sound documentary. Whereas the former attempts to record what is left from the soundscape that surrounded the last free Chiricahua Apaches, the latter intends to document the refugee children crisis in the context of the Mexico-US border. As I contend, through the inventory of echoes, the novel addresses colonization processes and draws attention to the environmental challenges faced by the Sonoran Desert. This is achieved because of two reasons. First, due to the centrality of the biome’s acoustic ecology. Second, because of the cultural and ecological components that accompany the repetition of the word “saguaro” in a section of the plot. In the case of the sound documentary, I analyze the methods through which this project highlights the weaponization of the desert against migrants. As I argue, this is achieved through a collection of acoustic shadows that appear in the form of radio waves, verbal reenactments, and an apocryphal book. Thus, the novel depicts the desert as a central device in border-control strategies and an ecosystem, or what I term a border biome, and as Native land.