Aronia berries possibly. Elders start so small, I can't imagine there would be much left to them now, but it appears they were still hanging on to the stems they grew on. That seems odd to find those in a crop at this time of the year....July or August seems more likely for berries to be eaten. I am 75 miles from MN, so elder or aronia are possible. Aronia would most likely be cultivated, can be in wildlife plantings, a denser, shorter bush. The elder berry is a usually growing wild the bush is more "loose" with a thicker, almost brittle stock. Thus ends my knowledge of purple colored berries. Whatever they are, that rooster was getting after them!