3.2. Preference experiments Blackbirds reliably discriminated between untreated sunflower seeds and those treated with 1778 ppmanthraquinone (F1,10 = 175.39, P < 0.0001). Blackbirds consumed an average of 0 0.2 g of treated sunflower and
6.5 0.4 g of untreated sunflower during the 4-day experiment (Fig. 4a). We observed no treatment by day interaction