Non-foraging tool use in European Honey buzzards: an experimental test

Between 30 June and 10 July 2013 we conducted a field experiment in central Spain to investigate the suitability of different plant species to attract ants as a tool used by European Honey buzzards (Pernis apivorus) in anting behaviour, under the assumption that buzzards would prefer easy-to-collect twigs from plants that effectively attract ants to perform anting behaviour. First, we estimated the strength needed to break 30 fresh twigs from the species that the buzzard used most frequently (maple tree), as well as from other abundant plants in the community, including rock rose, hawthorn, and Pyrenean oak. Second, we conducted a selection experiment at 23 random points to compare the effectiveness of ant attraction by these four species, measured as the total number of ants attracted