Indirect evidence for body size reduction in a flightless island bird after human colonisation

Abstract

Rhynochetos orarius has been described from Holocene fossils as the sister species of the smaller extant Kagu Rhynochetos jubatus, a bird endemic to New Caledonia. However, we argue that there has never been evidence justifying the description of R. orarius. Additionally, for biogeographical reasons it seems unlikely that two Kagu species would have evolved in New Caledonia. We therefore synonymise R. orarius and R. jubatus and postulate that Holocene Kagu were larger than today probably because historic hunting by humans targeted larger birds in richer habitat.