Complexities of costing eradications

摘要: Conservation dollars are and likely always will be limiting. Spending those effectively efficiently is of pivotal importance (Wilson et al., 2006). Martins al. (2006) present an analysis economic costs invasive mammal eradications on islands that they claim ‘provide conservation planners with a robust, if preliminary, estimate the cost any proposed eradication programme.’ Given one society’s most powerful tools, this badly needed instrument (Donlan 2003). However, while we commend colleagues’ efforts goal, available data simply sadly insufficient to provide such tool. More importantly, providing naive tool potentially misleading dangerous for land managers, practitioners philanthropists who may turn pages journals guidance. The costing campaigns complex process. As quantitatively demonstrated by colleagues, island area plays major factor in variation costs. Using general linear models dataset included 41 campaigns, authors conclude ‘decision makers considering potential programmes need only know area, distance from airport (at least New Zealand region), species eradicated make internally consistent robust first-pass estimates costs.’ In reality, number factors examples strongly suggest not case. We briefly address five issues here. First issue fixed colleagues due efficiency gains ability remove mammals islands, should significantly cheaper today than 20 years ago. They go state ‘thus, hypothetical 10 km situated 100 airport, would decrease US$ 251 000 rodents were 1983 . 31 200 it done 2003.’ While correct suspecting detected effect their regression model indeed real, certain relationship does linearly efficiency. For example, conservative rodenticide bait alone aerial campaign US$60 – twice predicted total (assuming $4 per kg application rate 15 ha , Bell Labs, USA). few rodent used reported less at above rate, these conducted small ( 1 km) where either bait-station approach was used, or perhaps lower but still successful island. Of worldwide rates past broadcasts, now common method eradications, mean 17.6 which as more sometimes necessary (range 10–35, n=16; C. J. Donlan, unpubl. data). Secondly, variable have substantial impact realized campaign. acknowledge local important, fail appreciate factors. Important include (1) needs mitigate non-target species, (2) techniques (e.g. stations versus broadcast eradications), (3) level capacity present, (4) amount environmental compliance required (5) levels bureaucracy. using helicopter depends largely isolation nearest port remote increasingly boat based), station labor These can influence overall order magnitude. Black rats Rattus rattus recently Anacapa Island, CA, USA (Howald 2005). Island first aerial-based