Assessing multiple threats to threatened species

Many species of conservation concern are in decline due to threats from multiple sources. To quantify the conservation requirements of these species we need robust estimates of the impact of each threat on the rate of population decline. However, for the vast majority of species this information is lacking. Here researchers demonstrate the application of integrated population modelling as a means of deriving robust estimates of the impact of multiple threats for a
rapidly declining koala population in SE Queensland. Integrated population modelling provides a basis for reducing uncertainty and bias by formally integrating information from multiple data sources into a single model.

The researchers quantified mortality rates due to threats from dog attacks, vehicle collisions and disease and the extent to which each of these mortality rates would need to be reduced, or how much habitat would need to be restored, to stop the population declining.
They show that the integrated population modelling approach substantially reduces uncertainty. They also show that recovery actions that only address single threats would need to reduce those threats to implausibly low levels to recover the population. This indicates that strategies for simultaneously tackling multiple threats are necessary; a situation that is likely to be true for many of the world’s threatened species.

More info: Jonathan Rhodes

Rhodes JR, CF Ng, DL de Villiers, HJ Preece, CA McAlpine & HP Possingham (2011). Using integrated population modelling to quantify the implications of multiple threatening processes for a rapidly declining population. Biological Conservation 144: 1081–1088.

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