Improving estimates of biodiversity loss

Quantifying the magnitude of human-induced biodiversity loss is a critical yet daunting challenge. Recently, species extinction rate estimates using island biogeography theory have once again been called into question. Here we highlight two of the many factors making the traditional application of this approach problematic for measuring biodiversity loss: first, the extreme assumption that native habitats are surrounded by a sea of human enterprise largely incapable of sustaining native biodiversity and, second, the sole use of species-level extinction estimates, which always underestimates the loss of biodiversity. Here we show that a wide array of taxa make human-dominated, farming countryside their home beyond the borders of native habitats. With data on native tropical birds, we show how simple species numeration masks dramatic differences between habitat types in community composition (e.g. species diversity or functional diversity). Overlooking the countryside biota, coupled with a scientific paradigm that underestimates biodiversity loss by equating it with species extinction, will only exacerbate the ongoing crisis. This is especially true given the rapid expansion and intensification of agriculture threatening countryside biotas, and a persistent limited understanding of how population extinctions and changes in community composition alter ecosystem functioning and services that support human life and wellbeing.