At this point there is well over a quarter century of research in the field of conservation biology assessing the wisdom of using surrogate species to guide conservation planning. Time and again researchers have warned of the risks associated with poorly informed use of surrogates, indicators, or proxy measures. A very recent example is an investigation by Fang Wang and colleagues, The hidden risk of using umbrella species as conservation surrogates: A spatio-temporal approach, published in Biological Conservation.
Wang and his colleagues evaluate use of the giant panda as an umbrella species to protect sympatric mammals, evaluating the panda and eight other mammal species using camera trap data, remote sensing data, studies on land features, and modeled habitat suitability. The authors note that the potential extinction of the iconic giant panda led Chinese authorities to create a reserve network to protect that species in the early 2000s. It was expected to incidentally contribute to the conservation of other species. Wang et al. show that, partly as a result of those efforts, the status of the giant panda has improved. At the same time, they note that several of the sympatric species have experienced dramatic population declines. This led the authors to evaluate habitat trends for all the species in order to assess the effectiveness of the nature reserve system. The authors found that the Asiatic black bear and forest musk deer are not adequately protected by the nature reserve system targeting pandas and recommend incorporating multi-species habitat restoration plans into the reserve system.
The reminder that rigorous validation should precede the use of surrogate species – alternatively referred to as umbrella or indicator species – in conservation planning is relevant in California’s Bay-Delta and elsewhere. This is the case because regulators continue to use surrogate species to inform decision-making. For example, California’s State Water Resources Control Board is in the process of developing biological goals to inform regulatory requirements in the Bay-Delta. In a report entitled Developing Biological Goals for the Bay-Delta Plan: Concepts and Ideas from an Independent Scientific Advisory Panel, a review panel charged with the development of methods for formulating such biological goals advocated for the use of indicator (or surrogate) species. The panel explains that the objective should be to identify species that are more readily sampled that can serve as indicators for species that rarely encountered or dangerously imperiled, which have similar ecological, physiological, and behavioral characteristics. Where a validation procedure is employed to assure that a surrogate responds similarly to environmental phenomena as a species needing management attention, use of surrogate species has the potential to yield conservation benefits. But where surrogate relationships are not confirmed with data, but are simply presumed to exist, the potential for incorrect inferences regarding the status and trends of a targeted, at-risk species or misdirecting management actions can be great. In that circumstance a directed conservation agenda can be costly without realizing intended benefits to the species of conservation concern.
Read the original article — Wang F. et al. 2020. The hidden risk of using umbrella species as conservation surrogates: A spatio-temporal approach. Biological Conservation 253:108913.
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