Battle for our Birds is the coordinated pest control response to a probable predator plague cycle caused by a mast (heavy seeding) event. These events predominantly occur in beech forest but can be found in podocarp forests and some tussock lands. The effect of this heavy seeding is a boost to rodent and stoat populations.
Locations where pest control work should occur are identified by a combination of variables:
- Probable rodent population change, which is determined by a mixture of computer modelling, beech seed counts and on-going rodent monitoring to confirm projected rodent population increases.
- The value of species threatened by an increase in rodent populations. Some species, such as mohua and orange-fronted parakeets, are more likely to be heavily affected by greater-than-usual predation by rats and stoats.
Operations are timed to break the cycle by killing rats (and stoats by secondary poisoning) in winter and spring.
Find out more here.
Why is OSPRI involved?
OSPRI became involved in the Battle for our Birds programme for two key reasons:
Large-scale rodent control using aerially applied 1080 toxins also greatly reduces possum populations. This is an objective of the TBfree programme, managed by OSPRI. Where areas of ecological interest for DOC overlap with areas of Vector Risk for the purpose of disease control, such as the Kahurangi National Park, TBfree has made substantial extra gains through BFOB activity. The TBfree programme can also be somewhat flexible in the timing of operations. Therefore we were able to treat adjoining areas which increased the total area of land receiving some form of rodent control and possum control.
OSPRI is recognised as a leader in the delivery of large-scale aerial 1080 operations, with a high level of expertise and a pool of experienced contractors. The treatment requirements for major mast events and OSPRI's capability suits an arrangement for the management of operations where both organisations' objectives coincide.
BFOB results 2016
Overall the 2016 Battle for Birds was a success with rodent populations greatly reduced over approximately 766,000 hectares of ecological priority. Of this area, OSPRI delivered approximately 390,000 hectares of aerial control and undertook TBfree control activity over another 90,000 hectares immediately adjacent.
This area of control allowed iconic species such as kea, mohua and whio to have a moderately successful breeding season despite the mast event. In the case of the mohua, the mast event posed a risk of local extinction in some areas which was averted by this work. An additional benefit was the lowering of the possum population, which will enable vegetation to recover and reduce competition with native species for food.
Rodent tracking results and the wider positive impacts on key native species can be explored here.