Red Poop from Birds at the Feeder

Connecticut bird watchers, are your birds leaving red droppings under the bird feeder? Why are my birds pooping red? With all the birds found dead or dying around the globe, I can't but feel worried about my faithful friends who visit my feeder daily. Red poop or purple poop is not strange when birds are eating berries saturated in color, but what about in the dead of winter? I'm concerned.