Birds as biodiversity surrogates: will supplementing birds with other taxa improve effectiveness?

Summary 1.  Most biodiversity is still unknown, and therefore, priority areas for conservation typically are identified based on the presence of surrogates, or indicator groups. Birds are commonly used as surrogates of biodiversity owing to the wide availability of relevant data and their broad popular appeal. However, some studies have found birds to perform relatively poorly as indicators. We therefore ask how the effectiveness of this approach can be improved by supplementing data on birds with information on other taxa. 2.  Here, we explore two strategies using (i) species data for other taxa and (ii) genus‐ and family‐level data for invertebrates (when available). We used three distinct species data sets for sub‐Saharan Africa, Denmark and Uganda, which cover different spatial scales, biogeographic regions and taxa (vertebrates, invertebrates and plants). 3.  We found that networks of priority areas identified on the basis of birds alone performed well in representing overall species diversity where birds were relatively speciose compared to the other taxa in the data sets. Adding species data for one taxon increased surrogate effectiveness better than adding genus‐ and family‐level data. It became apparent that, while adding species data for other taxa increased overall effectiveness, predicting the best‐performing additional taxon was difficult. Finally, we demonstrate that increasing overall effectiveness required supplementary data for several additional taxa. 4. Synthesis and applications . Good surrogates of biodiversity are necessary to help identify conservation areas that will be effective in preventing species extinctions. Birds perform fairly well as surrogates in cases where birds are relatively speciose, but overall effectiveness will be improved by adding additional data from other taxa, in particular from range‐restricted species. Conservation solutions with focus on birds as biodiversity surrogate could therefore benefit from also incorporating species data from other taxa.