Food preferences by birds using bird-feeders in winter: a large-scale experiment

Background: Intentional winter bird feeding in gardens is one of the most common interactions between birds and humans. Because feeding may have both desired effects (provisioning of nutritious food for under-nourished birds) and undesired effects (favouritism of competitively superior species, transmission of disease), management of supplementary sites should be optimized from an ecological and conservation perspective. Therefore, the main aim of this study was to experimentally test winter food preferences of birds, with underlying potential influence of habitat (rural vs. urban) on realised food preferences pattern. Methods: We conducted an experimental analysis of food preferences of wintering birds by provided bird-feeders in urban and rural environments across Poland. Data were collected twice during winter 2013-2014 across Poland, in total with 80 experimental trials. Results: Sunflower seeds were the most preferred food supplement both in urban and rural habitats, significantly more exploited than any other food simultaneously available in feeders (animal fat, millet seed and dry fruits of row-anberry). However, no significant differences were recorded between urban and rural habitats in use of food. Conclusions: The degree of use of a particular type of food at bird-feeders depended on the overall use of food in a bird-feeder-consumption of each of the four types of food was significantly positively correlated with that of the others, and it was positively correlated with the number of birds observed at the feeders.