Lessons learnt
Fairy prion being fed
Lessons learnt so far from the Mana Island programme:
- Introduced mice can be eradicated from islands over 200 ha.
- A comprehensive ecological restoration plan has been invaluable to guide effective collaboration between the central government managers of the island (DOC) and a dedicated community restoration group (FOMI).
- Homing instincts of burrow-nesting petrels can be overcome by translocating (and hand-feeding) downy nestlings, and providing artificial burrows and simulated colony sounds.
- An artificial diet based on sardines preserved in soya oil is an excellent diet substitute for well-developed nestlings of petrels that naturally feed predominantly on either fish or planktonic crustaceans.
- Starlings that arrive to roost each evening from the adjacent mainland were not major dispersers of seeds of invasive boxthorn and boneseed (neither species was identified among 42,093 seeds collected under starling roosts).
- Boxthorn and boneseed can be reduced to low densities and effectively eliminated as components of the coastal shrub community.
- Endangered takahe productivity on lowland islands can equal or exceed their productivity in the alpine grasslands of their predator-induced refugia in Fiordland.
- Damage to plantings by pukeko (purple swamphen) can be minimised by using drainage-pipe cloches for the first 12 months.
Bait station and tracking tunnel
The major management tasks to ensure the ongoing ecological recovery of Mana Island are focused on biosecurity, particularly measures to minimise the risk of rodent re-invasion and new pest incursions, regular audit for rodent presence/absence, and weed control (especially boxthorn, boneseed, Senecio glastifolius and kikuyu grass).
Tree planting has recently moved onto a new phase of inter-planting smaller numbers of successional canopy species within established cover of pioneer species. Initial seabird translocations have been completed, but monitoring of their return and breeding establishment continues. Planning is underway for translocations of whiteheads, bellbirds, and captive-reared Whitaker's skinks and robust skinks.
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