The influence of supplemental feeding on survival, dispersal and competition in translocated Brown Teal, or Pateke (Anas chlorotis)

Abstract

Supplemental feeding is widely used after the translocation of animals and is presumed to increase post-release survival or reproductive output. However, the results of empirical studies on supplemental feeding are equivocal and research is needed to determine the mechanisms by which supplemental feeding affects health and behaviour. Here, we studied the effect of supplemental feeding on the Brown Teal, or Pateke (Anas chlorotis), an endangered duck endemic to New Zealand, following four translocations of captive-bred individuals. Radio-telemetric monitoring showed no significant effect of supplemental feeding on post-release survival. Male birds dispersed further than females, and supplemental feeding decreased post-release dispersal. To reduce heterospecific competition at Brown Teal feeders, we also tested an exclusion device designed to prevent the main heterospecific competition, the Purple Swamphen (Pukeko in New Zealand, Porphyrio porphyrio melanotus), from accessing supplemental food. Although this device decreased the presence of Purple Swamphens at feeders, it also decreased use of feeders by Brown Teal. Ultimately, we concluded that supplemental feeding has value as a conservation tool for Brown Teal, particularly during releases in managed areas. Further studies on feeder design, as well as spatial and temporal patterns of use of feeders, are needed to maximise the positive effect of supplemental feeding on success of translocations.