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Red deer (Cervus elaphus) established on 8,140 ha Secretary Island after swimming from the mainland in the early 1960s. Attempts to remove them began in the 1970s and after several starts and stops they were eradicated in late 2014. Since late 2006, 688 deer have been removed. Ground hunters killed 365 deer in 1,827 hunter-days, 320 deer were shot from helicopters in 211 ?ying-hours, two deer were trapped and one was known to have been killed by a ?sherman. The campaign since 2006 was planned in three phases – an initial population reduction, a mop-up phase and a surveillance and rapid response to any new immigration phase. An initial reduction of 80% of the population, between 530 and 550 in 2006, was planned and achieved in the ?rst two years. The removal of surviving deer was planned to take a further four years but despite 114 being shot and probably less than 14 deer remaining in 2013 eradication was not achieved using the methods that succeeded in the initial phase. The change in tactics in 2014 that allowed for eradication was to (a) ground survey the island and use camera traps to locate areas with deer, (b) identify individual deer from faecal DNA to estimate numbers, know when they were shot or still alive, and to estimate potential new immigration from the mainland – which was low, and (c) move from individual hunters seeking any deer within a widespread population, when about 10% of hunter-deer encounters led to a kill, to re-train hunters as teams using GPS/radio systems and integrate them with aerial hunting to seek individual deer at known locations, when 100% of encounters led to a kill. The change of tactics that led to eradication success required about half the costs, i.e. $25,000 to $10,500 per deer direct operational costs, expected if no change had been made.

Aerial baiting from helicopters with a bait-sowing bucket and GPS to ensure coverage with anticoagulant toxins in cereal-based baits can reliably eradicate rodents on islands. Current best practice for temperate islands is to bait in winter when the rodents are not breeding, rodent numbers are lowest so competition for toxic baits is lowest, natural food is likely to be scarce, and many non-target species are absent from the island. However, short winter day lengths at high latitudes restrict the time helicopters can fly and poor weather in winter may increase risks of failure. This paper notes precedents from cool temperate islands where baiting was not conducted in winter and then uses the extensive data on mice on Marion Island to explore whether current recommendations for winter baiting based on breeding and natural food availability are important risk factors in determining time of year to bait. Marion Island mice do not breed between early May and late September, mouse densities reach a maximum in May and minimum in November, but the biomass of main natural food (invertebrates) does not fluctuate greatly over the year. This means the per capita food availability is least in autumn and increases through winter to most in spring and summer. The weight of the stomach contents of mice is also highest in winter. Based on this per capita food parameter, mice are likely to be most hungry between about March and May suggesting baiting would be more effective in this period (perhaps towards the end of it when breeding stops) than in the more traditional winter season.

About 150feral goat herds occupy about 16% of New Zealand. They are pests because of their effects on indigenous biota. Since 1936, government agencies have attempted to eradicate or control many herds. Common flaws in control campaigns include confusing ends (protection of resources) with means (killing goats), no measures of effectiveness, and lack of sustained action where eradication is impossible. One of four strategic options may be adopted: no action--giving a stable but undesirable outcome; eradication-- giving a stable and desirable outcome; annual sustained control-- giving a stable and desirable outcome but only if inherently fickle government effort is sustained; and occasional sustained control--giving unstable outcomes with or without the desired results depending on the goals and hunting frequency. Control tactics used are hunting on foot with or without dogs, hunting from helicopters, poisoning natural foliage, and fencing.