Have you noticed any sick birds on your property? Birds are very good at hiding sickness, but some clues to look for are birds that do not move around much or fly very often (so that they can conserve their energy), sitting with their feathers ruffled, dull eyes, and fecal staining around the cloaca. Even well-kept bird feeders and bird baths can promote the spread of disease because birds are in closer contact with one another than they would be under normal feeding conditions. The holes could be from other birds pecking at the sparrows after they have died. Please feel free to e-mail me if you have more questions or if you have not noticed any sick birds.