Boakes, E.H., McGowan, P.J.K., Fuller, R.A., Chang-qing, D., Clark, N.E., O’Connor, K. & Mace, G.M. 2010. Distorted views of biodiversity: spatial and temporal bias in species occurrence data. PLoS Biology, 8, e1000385.
Historical as well as current data on species distributions are needed to track changes in biodiversity. Species distribution data are found in a variety of sources but it is likely that they include different biases towards certain time periods or places. By collating a large historical database of ~170,000 records of species in the avian order Galliformes, dating back over two centuries and covering Europe and Asia, we investigate patterns of spatial and temporal bias in five sources of species distribution data: museum collections, scientific literature, ringing records, ornithological atlases, and website reports from “citizen scientists.” Museum data were found to provide the most comprehensive historical coverage of species’ ranges but often proved extremely time-intensive to collect. Literature records have increased in their number and coverage through time, whereas ringing, atlas, and website data are almost exclusively restricted to the last few decades. Geographically, our data were biased towards Western Europe and Southeast Asia. Museums were the only data source to provide reasonably even spatial coverage across the entire study region. In the last three decades, literature data have become increasingly focussed towards threatened species and protected areas, and currently no source is providing reliable baseline information—a role once filled by museum collections. As well as securing historical data for the future and making it available for users, the sampling biases will need to be understood and addressed if we are to obtain a true picture of biodiversity change.
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