Red-Winged Blackbird (Agelaius-Phoeniceus L) Feeding Response To Oil And Anthocyanin Levels In Sunflower Meal

Bird damage to sunflowers might be reduced by the development of resistant cultivars. Neagra de Cluj may be one such cultivar, with high levels of anthocyanin (a possibly aversive flavour) in achene hulls, but low oil yield. Four experiments were designed to assess the importance of oil content and anthocyanin concentration in feeding preferences expressed by red-winged blackbirds ( Agelaius phoeniceus L.). Differences in oil concentration of 15% (w/w) were reliably discriminated in two-choice tests: higher concentrations were preferred. Conversely, all anthocyanin concentrations (0·5, 1·0, 2·5 and 5·0% [w/w]) were avoided, and two-choice tests suggested that higher concentrations (2·5 and 5·0%) were relatively more aversive. Both anthocyanin concentration and oil content could influence Neagra de Cluj resistance to bird depredation. Of these two characteristics, oil may be relatively more important.