Deadly trap or sweet home? The case of discarded containers as novelty microhabitats for ants

Abstract

The presence of anthropogenic waste in the environment is one of the most pervasive pollution problems affecting wildlife around the world. Among different types of rubbish, beverage containers represent an ecological trap for invertebrates. However, it also may serve as a nest site. In the present study, we aim to assess if ants can exploit discarded containers as nesting sites, the intensity of mortality of ant workers foraging discarded containers, and ant preferences toward particular features of containers. The study was conducted in September 2018 in 10 woodland areas in the city of Wrocław, Poland. In total, 4.4% of 939 collected containers were used as nest sites by four ant species. Additionally, we found 698 dead workers, representatives of at least 11 species, in 10.3% of investigated containers. Most frequently, ants inhabited brown plastic and glass bottles, and an increase in neck diameter of containers decreased the possibility of nest occurrence. Dead workers were marginally significantly more often found in colourless glass bottles when compared to brown ones and were more frequent in sweet drink and vodka bottles than in beer bottles. Additionally, larger capacity increased the frequency of occurrence of dead ants. Although ants use anthropogenic waste as nest sites, it predominantly appears as a threat for foraging ant workers, most probably attracted by the smell of fermenting beverages or decomposing carcasses of previously trapped animals. Thus, to protect species inhabiting human-disturbed habitats, we suggest developing tools helping to prevent the accumulation of waste in urban woodlands.