A microphone recording six straight days, hanging two meters high, cannot distinguish between a pretty forest and a functional one. The findings were published on February 4, 2026, in Global Change Biology, with an open-access version available on PubMed Central. All of the natural regeneration and plantation sites belong to Costa Rica’s Payment for Environmental Services (PES) program (Pago por Servicios Ambientales). In contrast, plantations were barely 1.24 times closer in sound to a reference forest than to a pasture—a far more modest advancement. This distinction is particularly noticeable during the dusk chorus, the time of day with peak bird and insect activity: this is where natural regeneration most closely mirrors the pattern of an intact forest.