Kaka nomads - links between Great Barrier and the Mainland

by John Ogden and Todd Landers

Readers of the ‘Environmental News’ may recall that The Great Barrier Island Environmental Trust organised kaka counts in 2007, 08, 09 and 10. The results were summarised in EnviroNews #24, 2011, and demonstrated that in winter kaka numbers on the Island decline to about half their summer abundance of 200-300 birds. Numbers start to decline in April or May, coincident with an increase on the mainland (Suzi Phillip’s Kaka Watch data; see: www.kakawatchnz.org). Kaka return to Great Barrier in September or October, when they also decline on the mainland. These results suggested the importance of Great Barrier as a breeding and ‘exporting’ location for these endangered parrots, but, strictly speaking they didn’t ‘prove’ the annual movements.

Satellite tracking of kaka captured at Glenfern Sanctuary, by a group of researchers from Auckland Council (Research, Investigations and Monitoring Unit) and the School of Biological Sciences at the University of Auckland, has clearly demonstrated the reality of this annual movement pattern (Fig 1). This migratory pattern has been found in two tracked birds to date, with the other five kaka in this study remaining on Great Barrier Island over the winter. (Glenfern Sanctuary is certainly a favourite location for Great Barrier kaka during winter: EnviroNews #24, 2011 Table 3). Of course this study has only tracked seven kaka, and thus others may go else-where – to Little Barrier, Whangaparoa, or the Waitakere ranges for example.

The map shows the movement of a satellite-tracked kaka (bird 121220) in 2013. The bird left Glenfern Sanctuary in early April and was next recorded on the Hauraki Plains east of Hamilton about a week later. It stayed in that vicinity until late September, when it started its flight back to GBI. After a brief stopover in Coromandel it arrived back at Glenfern in early October. Map from Todd Landers, Auckland Council (Research, Investigations and Monitoring Unit).

A special thanks to Scott Sambell and Emma Cronin at Glenfern Sanctuary for their help in facilitating the satellite-tracking study. 

Environmental News Issue 33 2016