Abstract
Species interactions matter to conservation. Setting an ambitious recovery target for a species requires considering the size, density and demographic structure of its populations such that they fulfill the interactions, roles and functions of the species in the ecosystems in which they are embedded. A recently proposed framework for an IUCN Green List of Species formalizes this requirement by defining a fully recovered species in terms of representation, viability and functionality. Defining and quantifying ecological function from the viewpoint of species recovery is challenging, both in concept and application, but also an opportunity to insert ecological theory into conservation practice. We propose two complementary approaches to assessing a species’ ecological functions: a confirmation approach that starts with a list of the interactions of the species, identifying the ecological processes and the other species that are involved in these interactions, and quantifying the extent to which the species contributes to the identified ecological process; and an elimination approach that infers functionality by ruling out symptoms of reduced functionality, analogous to the Red List approach that focuses on symptoms of reduced viability. Despite the challenges, we believe that incorporation of functionality into species recovery planning is possible in most cases. It is also an essential element of an aspirational conservation vision that goes beyond preventing extinctions, aiming to restore a species to levels beyond what is required only for its own viability. This vision focuses on conservation and recovery at the species level, but also sees species as embedded in ecosystems, influencing and being influenced by the processes in those ecosystems. Thus, it connects and integrates conservation at the species and ecosystem levels.