Direct and indirect effects of 1080 on South Island robin populations in the Marlborough Sounds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Manawatū, New Zealand
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2019
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Massey University
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Pest control efforts are vital for the long-term survival of biodiversity native to New Zealand. Improvements to control methods, techniques and application methods are constantly made. In this thesis, I assessed the efficiency of aerial 1080 applications, in regards to survival rates and nest success of adult South Island robins (Petroica australis). Applications used a 1 kg sowing rate of 6 g cereal pellets containing 0.15% of sodium fluoroacetate per ha. SI robins were monitored in Tennyson Inlet, Marlborough Sounds, from 2012/13 – 2016/17. Nest cameras were used through two aerial 1080 applications and a beech mast. Nest outcomes were successfully captured in 83% of 210 nests monitored, identifying the cause and time of failure or the number of fledglings produced. Nests were most commonly preyed on by rats (Rattus spp). Rats were also the sole predator to kill brooding or incubating females. We found that adult survival and nest success were both negatively affected by increases in rat tracking rates. Aerially applied 1080 pest control increased nest success by 43% in 2013 and by 47% in 2014. Our study did not show any direct negative effects of aerial 1080 pest control for SI robins under current application methods and sowing rates. However, the benefits from the pest control efforts were short lived. Two years after the beech-mast-1080 application, rats were causing proportionately more nest failures than during the beech mast season. To achieve long-term population benefits for SI robins, future pest control operations may need to use higher 1080 sowing rates or multiple applications after a beech mast event.