Using community engagement and biodiversity surveys to inform decisions to control invasive species: a case study of yellow crazy ants in Atafu, Tokelau

Abstract

For conservation ecologists, the justification for restoration that involves the removal of invasive species is often made on the perception of impacts on biodiversity. However, invasive species control decisions can also be driven by the perceived direct impacts on people. Our case study reports on the ecological and human perspectives that drove the decision to control yellow crazy ants in Atafu, Tokelau. We surveyed the effects of yellow crazy ants at varying abundance on attitudes of people, diversity of ant communities, and white tern nesting behaviour in Atafu. Direct effects of yellow crazy ants on people included complaints that they ‘ruined the garden’, ate the ‘food for pigs that is kept outside’, and residents in areas with high ant infestations ‘can’t sleep outside anymore’. Yellow crazy ant abundance was positively correlated with both negative impacts on common ant species and the concern people expressed over the effects of the ant on their lives, but was not associated with differences in ant species richness or invertebrate diversity. We also found that yellow crazy ant abundance was negatively associated with the reproductive output of white terns. In addition, we found that people and white terns were more sensitive than ant communities to the effects of yellow crazy ants when the ants were at lower abundance. Based on our surveys of impacts on the villagers and biodiversity values on Atafu, the decision was made to embark on a control program, which was predicted to benefit both people and the environment.