Data and code from: Moving towards better risk assessment for invertebrate conservation

Among the most widely used information underpinning international
conservation efforts is the IUCN Red List of endangered species. The Red
List designates species extinction risk based on geographic range,
population size, or declines in either. However, the Red-List has poor
representation of invertebrates, which comprise the majority of animal
diversity, and it has frequently been questioned whether Red List criteria
are appropriate for these organisms. Due to their small size, difficulty
in identification, and general rarity, many invertebrates are hard to
study, making the Red List criteria difficult to apply. Here we discuss
these criticisms in the context of empirical evidence from one of the
largest terrestrial arthropod surveys to date, documenting the abundance
and distribution of over 13,000 species in Sweden. Using simple empirical
examples from these data, we argue that even the most ambitious monitoring
efforts are unlikely to produce enough observations to reliably estimate
population sizes and ranges for more than a fraction of species. Thus,
there is likely to be substantial uncertainty in classifying most species
according to current criteria. In response, we discuss the introduction of
potential new IUCN criteria to more accurately capture the conservation
needs of invertebrates, and to increase the representation of
invertebrates on the IUCN Red List.