Moa, climate, and eruptions: radiocarbon ages on habitat-specific moa show that their distributions were controlled by volcanic eruptions as well as climate

The species composition of moa assemblages reflected the local vegetation. These assemblages have been used as indicators of the geological age - glacial or Holocene - of the fauna. Within the assemblages, some species of moa have been associated with specific vegetation types, including Anomalopteryx didiformis with lowland rain forest, and Euryapteryx curtus, with dry shrubland. The sequence of radiocarbon ages for A. didiformis and E. curtus in the Waitomo karst, in the west central North Island, New Zealand, records changes in the distributions of their habitats over the past 28,000 years. The presence of A. didiformis shows that, contrary to current reconstructions, there was lowland rain forest in the karst during the Last Glacial Maximum. An abrupt change to E. curtus and hence of its shrubland habitat coincided with the Oruanui super eruption of Taupo volcano 25,400 years ago. Anomalopteryx didiformis and its rain forest habitat did not return to the karst until c. 13,000 years ago. E. curtus disappeared from the karst some time before that, during the gradual post-glacial warming, but remained elsewhere on the Volcanic Plateau, probably in the seral vegetation that followed the continual eruptions. Moa distributions were not always altered just by climate change. Major eruptions such as the Oruanui could change their habitat and hence their distribution over much of both main islands.