The Kunming-Montreal Global Biodiversity Framework (GBF) identifies an annual biodiversity funding gap of $700 billion. Given insufficient public funds, GBF Target 19 seeks to leverage private finance to fill this funding gap. Yet viable and scalable private conservation strategies remain uncommon (1). Here, we provide evidence that changes in local biodiversity can affect municipal borrowing costs using a case study of how a sudden decrease in bat populations, which weakens natural pest-control services provided to farms, affects the finances of US rural county governments. This connection between biodiversity and government borrowing costs creates a promising pathway for private conservation investment. Profit-seeking investors may strategically invest in a county’s municipal bonds when valuations are likely to change owing to shifts in the condition of local biodiversity. This investment strategy may allow investors to monetize conservation efforts by aligning their bond investment strategy with conservation actions.