Metrics and Equivalence in Conservation Banking

Offsets are increasingly used to compensate for unavoidable development impacts on species and habitats. Many offset programs pursue no net loss, but research on the success of these programs is lacking, including research on conservation banking’s success in conserving protected species under the US Endangered Species Act. This article provides a case study analysis of two conservation banks in the state of California, comparing the conservation gains provided by banks with the losses from development impacts. It provides an analysis of credits and metrics to determine whether the gains are equal to the losses in terms of type, condition, and amount. Results do show that the gains exceed the losses in terms of acreage. However, the program uses indirect metrics (acreage), and the equivalence of the losses and gains, besides habitat type and size, is not reflected. Banks provide a baseline in their documentation and conduct monitoring of species abundance and habitat quality, but they do not use it to measure additional conservation gains. More detailed metrics and transparent indices to certify the acres in production could allow for a quantification of conservation benefits and an evaluation of program success. However, selecting standardized metrics is challenging because they need to be species-specific to reflect the goal of species recovery, and still be operational in practice.