Litter buffet: On the use of trash bins by birds in six boreal urban settlements

Unintentional food resources in urban areas (street litter, food leftovers, overflowing trash bins) are dietary components of some urban-exploiter bird species. In this study, we report on 13 bird species in six southern Finnish cities using urban trash bins and describe differences in their activity when provided with food resources (i.e., bait) in different bin types. We used generalized linear models (GLM) and classification and regression trees (CART) to test for associations between environmental variables and bird activity at the binscapes. Bird activity at the binscapes significantly differed among all cities and among types of bins and was significantly higher after placing bait in all cases. Bins with the largest opening had more activity as opposed to those with smaller openings or lids. Corvids and gulls had the highest activity, with corvids usually being present before the bait was placed and gulls increasing their activity thereafter. These differences show that trash bin foraging is highly malleable and thus susceptible to management preventing its occurrence. Suitable waste management measures could aid in reducing the number of species close to bins and their surroundings, benefiting both bird and human health.