Nowadays, littering is one of the biggest challenges that environmental conservation is facing. Although beverage containers, such as bottles and cans, belong to the most common threats in this context, their effect on animals has been poorly studied. The aim of this study was to assess the diversity and mortality level of the animal taxa entering discarded containers and to investigate which container features influence the number and functional composition of the trapped animals. The study was conducted in 10 urban woodlands in the city of Wrocław, Poland. In total, 939 open containers were collected. In 56% of them, a total number of 10,162 dead individuals (10,139 invertebrates and 23 vertebrates) was found. The most common amongst them were insects (orders: Coleoptera, Diptera, Hymenoptera), malacostracans (Isopoda), arachnids (Opiliones, Sarcoptiformes) and gastropods (Stylommatophora). The number of dead animals was affected positively by the container capacity and was significantly higher in glass and plastic bottles when compared to aluminium cans. At the same time, the presence of a neck negatively affected the number of dead animals. Container capacity was also positively correlated with the abundance of the most common functional groups: predators, phytophages and saprophages. Moreover, colourless and green, but not brown, containers were a significant predictor for the abundance of the latter two groups. Our study revealed that discarded containers constitute an ecological trap for many groups of animals. There is an urgent need to reduce the amount of rubbish in the environment by, for example, the implementation of regional and international regulations addressing the problem of littering, or organising repeated clean-up and educational activities.
Keywords: Animal mortality; Central Europe; Discarded containers; Entrapment; Littering; Urban forests.
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