Those of us fortunate enough to have lived in Hamilton for a long time will know that for many years we only occasionally saw tūī and they were visitors outside the nesting season – but now they are back. A recent paper in Notornis (1), the Ornithological Society’s journal, has put some numbers around this and tracked the hugely beneficial effect of predator control in bush near Hamilton.
Starting in 2004 Manaaki Whenua – Landcare Research scientists captured and banded 51 adult tūī and fitted radio transmitters to 41 in and near Hamilton, Cambridge, and Te Awamutu so they could follow their movements. They found that tūī moved 5–23 km from urban areas to surrounding native forests to nest, but only four (29%) of 14 nests that were not protected by predator control fledged young. The main reason was predation by ship rats, kāhu/swamp harriers and possums.
With this information as a baseline, the Waikato Regional Council’s Hamilton Halo project was implemented, carrying out effective pest mammal control in bush areas within tūī flying distance of Hamilton.
Meanwhile a number of community groups and the City Council have carried out environmental restoration and predator control in the city, which provides increased and safe habitat for the growing tūī population to move into.
The research has confirmed greatly increased year-round tūī abundance and nesting in Hamilton. The results confirm previous findings that tūī move widely in winter; that they readily cross pasture in the absence of continuous forest corridors; and that they will permanently inhabit urban areas.
Provided adequate food is available, effective control of ship rats and possums can rapidly (1–4 years) increase tūī visits and nesting within 20 km of managed sites, enabling re-colonisation of nearby urban habitats by tūī, despite previous evidence that tūī tend to live and nest close to where they were hatched.
Birds New Zealand members can access the full paper from https://notornis.osnz.org.nz/node/4546.
Non-members can access Notornis papers from 1 year after publication.
1. Increasing urban abundance of tūī (Prosthemadera novaeseelandiae) by pest mammal control in surrounding forests; Neil Fitzgerald, John Innes, Corinne Watts, Danny Thornburrow, Scott Bartlam, Notornis, 2021, Vol. 68: 93-107.