Low detectability of alien reptiles can lead to biosecurity management failure: a case study from Christmas Island (Australia)

Abstract

When we assume that contemporary management actions will be effective against the global rise of emerging alien species, we can develop management complacency, which leads to potentially disastrous outcomes for native biodiversity. Here, we propose the use of the probability of detection as a metric to assess the feasibility of management actions for alien species. We explore how detectability can influence the management of alien reptiles, a group of emergent alien vertebrates globally. We use a Rapid Biological Assessment method (time-limited transects) to estimate the probability of detection for alien reptiles present on Christmas Island (Australia). Across the five species studied, we found low probabilities of detection and poor explanatory capacity of the individual covariates included in our models. These findings indicate that management options to deal with alien reptiles are limited due to the potential high cost and low efficacy associated with low probabilities of detection. Strict preventive strategies, firmly espousing the principles of adaptiveness and precautionary policies, combined with early detection and biosecurity response activities are needed to address the emergence of alien reptiles. Our research was focussed on alien reptiles on islands, but the rise of new pools of alien species from all taxonomic realms across the world suggests that our conclusions may be applicable more generally. Further research is called for to explore the applicability of our conclusions and recommendations to other taxonomic groups and regions of the world. A peer-reviewed open-access journal NeoBiotaPablo García-Díaz et al. / NeoBiota 45: 75-92 (2019) 76

Forecasting potential invaders to prevent future biological invasions worldwide

“…In another light, we have shown how macroecological patterns can also play a foremost role in assessing species' invasion risk. Our findings are consistent with previous studies in showing that species with large native geographic ranges are more likely to be transported and introduced (García‐Díaz et al., 2019; Tingley et al., 2010) and succeed in establishing alien populations (Allen et al., 2013; Cadotte et al., 2006; Duncan et al., 2001; Forsyth et al., 2004; Hayes & Barry, 2007; Hui et al., 2011). Notably, geographic range size has been used chiefly as a surrogate for more ecologically direct measures of invasion potential (Dukes & Mooney, 1999; Peterson et al., 2011; Williamson & Griffiths, 1996).…”

“…Our findings show that traits are relatively weak predictors for unintentional transport and introduction. Counter to the presumption that unintentionally transported and introduced alien species would have relatively small body sizes, which would allow them to easily contaminate or hitchhike on goods and vehicles unnoticed (Chapple et al., 2011; García‐Díaz et al., 2019; Kraus, 2009; Toomes et al., 2019), we found that these species range in body size from small to large. It is also for this same reason that our findings do not align with previous analyses on introduced alien amphibians and reptiles (Allen et al., 2017; see Supporting Information S9 for a table of studies on alien amphibian and reptile invasion success); however, these previous studies did not distinguish the traits of alien species that have been intentionally vs. unintentionally transported and introduced, which may have confounded their analysis (Pysek et al., 2011).…”

Use of mixed-type data clustering algorithm for characterizing temporal and spatial distribution of biosecurity border detections of terrestrial non-indigenous species

“…This reflects stringent preventative biosecurity protocols and the limited number of entry points to the island i.e. the seaports and airport [ 75 ].…”