Do hihi lose access to supplemental feeders because of the presence of korimako?

Supplemental feeding is now a ubiquitous and effective tool in the conservation management of wild populations. On Tiritiri Matangi Island, the persistence of the hihi (Notiomystis cincta) population depends on constant food supplementation. However, the more dominant korimako (Anthornis melanura) can also access these feeders. To understand whether korimako may be limiting hihi access to the feeders, we used an observational study to quantify the co-occurrences at feeders and potential for resource partitioning and competitive exclusion of males and females of both species. We measured hihi and korimako visits to sugar-water feeders and the frequency of territorial interactions during the non-breeding and breeding seasons. We found that male korimako were the most frequent visitors (116 +/- 7 visits h-1), followed by male hihi (51 +/- 3 visits h-1), female hihi (47 +/- 3 visits h-1), then female korimako (6 +/- 1 visits h-1). In general, visits positively correlated between each species and sex across months. Few intra- and interspecific aggressive interactions were observed in the non-breeding season and early breeding season. We found no evidence that hihi were being excluded from the supplemental feeders by korimako, potentially from the high visitation rates making territorial and aggressive interactions ineffectual.