Top predators: hot or not? A call for systematic assessment of biodiversity surrogates

1. Sergio et al. (2006) argue that top predators are justified conservation surrogates based on a case study where raptor presence is associated with high species richness of birds, butterflies and trees. 2. We question the methodology as well as the applicability of their results, and clarify differences between surrogates for biodiversity hotspots and surrogates for complementarity. We show that the results from Sergio et al. related to richness hotspots are not fully reliable and that the ability of top predators to identify complementary areas is not demonstrated. Given that complementarity-based surrogate studies have produced mixed results for a variety of reasons, we clarify some methodological misunderstandings while encouraging further testing of functional groups as biodiversity surrogates. 3. Synthesis and applications. We call for caution in making generalizations, and emphasize that case studies on the use of surrogates should be conducted in a systematic manner. This will facilitate robust assessment across studies regarding the usefulness of particular species groups as biodiversity surrogates.