V.R.F. was supported by a Balfour PhD studentship from the Department of Zoology, University of Cambridge; R.T. was supported by an Independent Research Fellowship from the Natural Environment Research Council U.K. (NE/K00929X/1) and a start-up grant from the Helsinki Institute of Life Science (HiLIFE), University of Helsinki. We are grateful to the Department of Conservation for permission to conduct this research under permit 44300-FAU, and for providing funding support to J.G.E. for management of the hihi population (monitored by M.M. and D.S. over the 3 years of this study). We also thank the Supporters of Tiritiri Matangi for their assistance during this study. We are very grateful to our Editor and three anonymous reviewers for their comments, which greatly improved the manuscript.