Development can pose a substantial threat to imperiled species listed under the US Endangered Species Act (ESA), particularly as two-thirds of these species rely on private lands. Habitat Conservation Plans (HCPs) outlined in Section 10(a)(1)(B) of the ESA have emerged as crucial instruments for harmonizing conservation and development needs. Yet, despite being established for over 30 years, the HCP program’s impact remains inadequately understood. Consequently, we evaluated 629 HCPs-covering 38 states and territories, and 748 species-to assess the program’s transparency, organization, and impact by examining three key factors: (1) the presence of required documents, (2) the adequacy of monitoring, and (3) the consistency of conservation measures. A lack of required documents made it difficult to quantitatively assess the overall impact of the program, including the adequacy of monitoring. Conservation measures outlined in the plans were also often inconsistent. Our findings indicate that enhancements are needed to modernize data management, increase transparency, strengthen oversight to improve the monitoring and evaluation of both individual HCPs and the program overall, and establish or update species conservation standards. These changes could significantly improve program functionality, streamline development and implementation processes, and offer greater opportunities to gauge success in the program.
