Juniper berries are a vital food source for birds in winter. I watch the birds strip the trees bare of berries within a week sometimes. All kinds of birds in one tree -- winter robins (many prefer not to migrate in my area) waxwings, catbirds, white throated sparrows, song sparrows, Juncos, mockingbirds, blackbirds, goldfinches. It's like one of those holiday cards that shows all different species of birds in a Christmas tree, only in real life. The trees seem alive with activity as birds hop up, down, and fly in and out of the tree.