This age has several important implications; firstly rat predation only began after 1280 which is much shorter period than previously implied and makes the risk to currently declining populations of rat-sensitive species more pressing as they could be diminishing faster than previously assumed.
The study, one of the largest studies of its kind, has shown that the country was not visited by humans over 2000 years ago, as some previous research suggests.
The work is published in the journal Proceedings of the National Academy of Sciences in the United States.
The first people arriving in New Zealand from tropical East Polynesia initiated an immediate and rapid transformation.
A precise date for the arrival of the rat helps us to fully understand both the history of human settlement and the past and present ecological impacts of kiore on native fauna and flora.
We have dated over 100 individual seeds, some rat-gnawed, others intact or bird-cracked, which show that rat gnawed seeds only occur in both the North and South Islands of New Zealand after about 1280 AD.
This is a D-section core collected from Te Rerenga in the Coromandel peninsula.Furthermore, the reliability of the bone dating has been questioned, with explanations for their anomalously old ages ranging from variations in laboratory pre treatments to bone contamination through either post-mortem processes or dietary- related offsets.Work, funded by the Royal Society of New Zealand Marsden Fund, has resolved the debate using several approaches.The presence of rat-gnawed seeds in this ash means that 1314 AD provides an upper age limit for initial rat arrival in New Zealand.Image - J Wilmshurst) nuts collected from spit 0-10cm, in Nguroa Bay, North West Nelson.The pen is pointing to a rat-gnawed seed found in-situ within the dark sandy layer.