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The majority of species at risk of being listed under the United States (U.S.) Endangered Species Act (ESA) relies on habitat located on privately owned land (Turner & Rylander, 1998). There are nu...

While invasive species eradications are at the forefront of biodiversity conservation, ant eradication failures are common. We reviewed ant eradications worldwide to assess the practice and identify knowledge gaps and challenges. We documented 316 eradication campaigns targeting 11 species, with most occurring in Australia covering small areas (

Stawitz and colleagues (2016) present an analysis of seafood mislabeling and make inferences about its financial and ecological implications. We applaud the authors for tackling this important topic. As presented, however, we have reservations about the research which call into question the main conclusions. First, based on the data and results that are presented, there appear to be errors and some of the conclusions are not supported. Second, there may be a bias in the analyses that favors the conclusions. Third, details are lacking regarding the analyses, challenging their verification. We briefly describe some of the issues. This article is protected by copyright. All rights reserved

Many ants are among the most globally significant invasive species. They have caused the local decline and extinction of a variety of taxa ranging from plants to mammals. They disturb ecosystem processes, decrease agricultural production, damage infrastructure and can be a health hazard for humans. Overall, economic costs caused by invasive ants amount to several billion US $ annually. There is general consensus that the future distributions of invasive species are likely to expand with climate change, however this dogma remains poorly tested. Here we model suitable area globally for 15 of the worst invasive ant species, both currently and with predicted climate change (in 2080), globally, regionally and within the world’s 34 biodiversity hotspots. Surprisingly, the potential distribution of only five species was predicted to increase (up to 35.8 %) with climate change, with most declining by up to 63.3 %. The ant invasion hotspots are predominantly in tropical and subtropical regions of South America, Africa, Asia and Oceanic islands, and particularly correspond with biodiversity hotspots. Contrary to general expectations, climate change and invasive ant species will not systematically act synergistically. However, ant invasions will likely remain as a major global problem, especially where invasion hotspots coincide with biodiversity hotspots.

Conservation practitioners are increasingly embracing evidence-based and return on investment (ROI) approaches. Much evidence now exists that documents island biodiversity impacts by invasive mammals. The technical ability to eradicate invasive mammals from islands has increased exponentially; consequently, strategic planning focused on maximizing the ROI is now a limiting factor for island restoration. We use a regional ROI approach to prioritize eradications on islands for seabird conservation in British Columbia, Canada. We do so by integrating economic costs of interventions and applying a resource allocation approach. We estimate the optimal set of islands for eradication under two conservation objectives each with a series of increasing thresholds of population sizes and breeding locations. Our approach (1) identified the most cost-effective interventions, (2) determined whether or not those interventions were nested with increasing thresholds, and (3) helped justify larger investments when appropriate. More often than not, conservation decisions are made at a regional scale, and decision-makers often must make choices on how to allocate funds across a number of potential conservation actions. A regional, ROI framework can serve as a decision-support tool for organizations engaging in discrete interventions in order to maximize benefits for the minimum cost.

Species distribution models (SDMs) have become an important tool to predict the impact of climate change on the distribution of a given species. Generally, projections for a chosen time horizon in the future are compared with the size of the species’ current distribution. In this study, we show that selection of the target time horizon can qualitatively alter the prediction of a species’ future distribution. We illustrate this by assessing the potential distribution of 15 invasive ant species in 2020, 2050 and 2080 at a global scale. Our results indicate that for 6 out of the 15 species modelled, the trend of potential habitat size (i.e., decrease or increase) changed over time following climate change. In four species, the sign of the trend changed, from an initial expansion to a subsequent reduction or vice versa, depending on the date projected to. In some cases, these changes were great (e.g., from an initial increase of 36.5% in 2050 to a decrease of −64.3% in 2080). Our findings stress the importance of using several projection horizons to avoid misled species management decisions.

Asclimaticallysuitablerangeprojectionsbecomeincreasinglyusedtoassessdistributionsofspecies, we recommend systematic assessments of the quality of habitat in addition to the classical binary classification of habitat. We devised a method to assess occurrence probability, captured by a climatic suitability index, through which we could determine variations in the quality of potential habitat. This relative risk assessment circumvents the use of an arbitrary suitability threshold. We illustrated our method with 2 case studies on invasive ant species. We estimated invasion potential of the destroyer ant (Monomorium destructor) and the European fire ant (Myrmica rubra) on a global scale currently and by 2080 with climate change. We found that 21.1% of the world's landmass currently has a suitable climate for the destroyer ant and 16% has a suitable climate for European fire ant. Our climatic suitability index showed that both ant species would benefit from climate change, but in different ways. The size of the potential distribution increased by 35.8% for the destroyer ant. Meanwhile, the total area of potential distribution remained the same for the European fire ant (>0.05%), but the level of climatic suitability within this range increased greatly and led to an improvement in habitat quality (i.e., of invasive species' establishment likelihood). Either through quantity or quality of suitable areas, both invasive ant species are likely to increase the extent of their invasion in the future, following global climate change. Our results show that species may increase their range if either more areas become suitable or if the available areas present improved suitability. Studies in which an arbitrary suitability threshold was used may overlook changes in area quality within climatically suitable areas and as a result reach incorrect predictions.

Small-scale habitat complexity has been shown to influence interspecific competition and resource use in ant communities. Nevertheless, in Mediterranean communities, where temperature variations have a stronger effect on the foraging of subordinate species than competition by dominants, the effect of small-scale habitat complexity on resource use by ants is unknown. We investigated the influence of an experimental spatial mosaic of microhabitats (interior, edge and open) on the dynamics of resource use in a guild of ants of a Mediterranean grassland. We used baits containing one of three food resource types (honey, tuna and seeds) placed in the different microhabitats. Variation in resource use among microhabitats appears to result from differential responses among ant species to small-scale spatial heterogeneity. Analysis of frequency of occurrence, number of foragers and monopoly at baits of ant species indicated that the resource use and recruitment intensity was modified by microhabitat, once the effect of temperature was removed from the analysis. Thus, foraging activity and competitive interactions of ant species were influenced by the different microhabitats apart from temperature, which suggests an effect of small-scale structural complexity. Small-scale spatial variations in structural complexity have an effect in resource use by most ants in this system that is not wholly explained by differences in temperature. Finally, this suggests that microhabitat may be one factor influencing the outcome of the dominance hierarchies.