A new study suggests that the flightless birds named moa were completely extinct by the time New Zealand's human population had grown to two and half thousand people at most.
The new findings, which appear in the prestigious journal Nature Communications, incorporate results of research by international teams involved in two major projects led by Professor Richard Holdaway (Palaecol Research Ltd and University of Canterbury) and Mr Chris Jacomb (University of Otago), respectively.
The researchers calculate that the Polynesians whose activities caused moa extinction in little more than a century had amongst the lowest human population densities on record. They found that during the peak period of moa hunting, there were fewer than 1500 Polynesian settlers in New Zealand, or about 1 person per 100 square kilometres, one of the lowest population densities recorded for any pre-industrial society.
They found that the human population could have reached about 2500 by the time moa went extinct. For several decades before then moa would have been rare luxuries.
Estimates of the human population during the moa hunting period are more sensitive to how long it took to exterminate the birds through hunting and habitat destruction than to the size of the founding population.
Complex Species Status for Extinct Moa (Aves: Dinornithiformes) from the Genus Euryapteryx
Authors:
Huynen et al
Abstract:
The exact species status of New Zealand's extinct moa remains unknown. In particular, moa belonging to the genus Euryapteryx have been difficult to classify. We use the DNA barcoding sequence on a range of Euryapteryx samples in an attempt to resolve the species status for this genus. We obtained mitochondrial control region and the barcoding region from Cytochrome Oxidase Subunit I (COI) from a number of new moa samples and use available sequences from previous moa phylogenies and eggshell data to try and clarify the species status of Euryapteryx. Using the COI barcoding region we show that species status in Euryapteryx is complex with no clear separation between various individuals. Eggshell, soil, and bone data suggests that a Euryapteryx subspecies likely exists on New Zealand's North Island and can be characterized by a single mitochondrial control region SNP. COI divergences between Euryapteryx individuals from the south of New Zealand's South Island and those from the Far North of the North Island exceed 1.6% and are likely to represent separate species. Individuals from other areas of New Zealand were unable to be clearly separated based on COI differences possibly as a result of repeated hybridisation events. Despite the accuracy of the COI barcoding region to determine species status in birds, including that for the other moa genera, for moa from the genus Euryapteryx, COI barcoding fails to provide a clear result, possibly as a consequence of repeated hybridisation events between these moa. A single control region SNP was identified however that segregates with the two general morphological variants determined for Euryapteryx; a smaller subspecies restricted to the North Island of New Zealand, and a larger subspecies, found on both New Zealand's North and South Island.
Giant moa bird (Dinornis robustus, literally meaning 'robust strange bird') may not have actually had robust bones, according to new research conducted by The University of Manchester. The leg bones of one of the tallest birds that ever existed were actually rather like those of its modern (but distant) relatives, such as ostrich, emu and rhea, the studypublished in PLOS One today (18 December) shows.
The study, led by biomechanics researcher Charlotte Brassey, in collaboration with palaeobiologist Professor Richard Holdaway at the University of Canterbury in New Zealand, has found that the largest of the moa species had leg bones similar to those of modern flightless birds that can run fast, whereas a much smaller species of moa – from a different family - had an extremely robust skeleton.
Ms Brassey said:"Our research suggests that this group of birds came up with several different solutions to deal with the problem of supporting the large body necessary to process a diet of coarse vegetation.
"We know that these species of moa were living together in the same locations, at the same time. So we don't think the differences we're seeing in leg robustness are adaptations to a particular habitat type.
"Instead it seems they were perhaps engaging in different behaviours, although both could deal with extremely rough terrain."
