Geographic profiling as a novel spatial tool for targeting the control of invasive species

Geographic profiling (GP) was originally developed as a statistical tool in criminology, where it uses the spatial locations of linked crimes (for example murder, rape or arson) to identify areas that are most likely to include the offender's residence. The technique has been successful in this field, and is now widely used by police forces and investigative agencies around the world. Here, we show that this novel technique can also be used to identify source populations of invasive species, using their current locations as input, as a prelude to targeted control measures. Our study has two main parts. In the first, we use computer simulations to compare GP to other simple measures of spatial central tendency (centre of minimum distance, spatial mean, spatial median), as well as to a more sophisticated single parameter kernel density model. GP performs significantly better than any of these other approaches. In the second part of the study, we analyse historical data from the Biological Records Centre (BRC) for 53 invasive species in Great Britain, ranging from marine invertebrates to woody trees, and from a wide variety of habitats (including littoral habitats, woodland and man-made habitats). For 52 of these 53 data sets, GP outperforms spatial mean, spatial median and centre of minimum distance as a search strategy, particularly as the number of sources (or potential sources) increases. We analyse one of these data sets, for Heracleum mantegazzianum, in more detail, and show that GP also outperforms the kernel density model. Finally, we compare fitted parameter values between different species, groups and habitat types, with a view to identifying general values that might be used for novel invasions where data are lacking. We suggest that geographic profiling could potentially form a useful component of integrated control strategies relating to a wide variety of invasive species.