In 2013 the US Fish and Wildlife Service and National Marine Fisheries Service proposed to amend existing regulations that implement the Endangered Species Act’s interagency consultation process by codifying their pre-existing practice of using surrogates to express the amount or extent of incidental take of listed species. The agencies contend that amendments both are necessary as a practical matter and are defensible on ecological grounds. They propose the use of surrogates, either in the form of a substitute species to fill in for a species that is challenging to observe, count, or otherwise measure, or a land-cover type or another habitat attribute, as a proxy for the amount or extent of anticipated take. In the article we contend that the proposed rule lacks description of a defensible process for surrogate selection and essential implementation details. We describe five obligatory steps in surrogate selection and validation. A validation procedure should clearly articulate the reasoning behind the selection of the surrogate, by describing the similarities in responses by the surrogate and the target species to the same environmental phenomena, by linking demographic responses to habitat extent and condition, and by describing the uncertainties that accompany the relationship between the status and trends of the surrogate and those of the target species or its habitat under in-common circumstances.
Murphy DD, Weiland PS. 2014. The use of surrogates in implementation of the federal Endangered Species Act – proposed fixes to a proposed rule. Journal of Environmental Studies and Sciences 4:156-162.