power analysis

Lesser short-tailed bats (Mystacina tuberculata) feed on arthropod taxa known to consume 1080 baits. Thus, they may be vulnerable to secondary poisoning after control operations for brushtail possum (Trichosurus vulpecula) using aerially broadcast 1080 baits. Short-tailed bat mortality was monitored during 11 days after 1080 baits were broadcast over their winter foraging area. Monitoring involved catching a sample of 269 bats as they arrived at a roost after foraging, then holding them in captivity for 48 hours.

Invasive mammalian herbivores (e.g. deer, feral goats and brushtail possums; hereafter ‘herbivores’) are widespread throughout New Zealand and their control is important for conservation. In addition to known biodiversity benefits, it has recently been suggested that herbivore control could lead to measureable carbon gains when aggregated across a large area of conservation land. However, a significant amount of uncertainty exists regarding the potential effects of herbivore control on carbon, and the practicalities of successfully implementing such projects.

In this study I assess the statistical power to detect a significantly greater increase in bird population size on treatment farms than on control farms given that there is a substantial treatment effect. Computer simulations of bird populations on New Zealand sheep/beef farms were used to generate significant changes in bird abundance from (a) controlling predation by introduced small mammals, (b) habitat structural complexity, and (c) an interaction of both.