Species distribution data are critical information sources when it comes to implementing the multiple Aichi Targets set by the international Convention on Biological Diversity. Although there have been international-scale efforts to aggregate distribution data, the magnitudes and locations of the gaps in biodiversity knowledge remain unclear. In this study, we use a large database, including over 200 000 species occurrence records, to identify knowledge gaps in biodiversity inventories for nine animal taxa in a Mediterranean biodiversity hotspot. Spatial modelling methods were employed to relate the completeness of inventories to population, road and protected area density. The completeness of faunistic inventories was correlated with the amount of protected areas, roads and population density. Despite more than 200 years of faunistic sampling, knowledge of the distributions of most animal taxa is still limited, especially for invertebrates. As the window of opportunity for achieving Aichi Targets 11 and 19 begins to close, means of filling such knowledge gaps are required. We argue that a combination of quantitative tools and citizen science data collection programmes may help inform conservation decisions.