Feeding birds is a wonderful way to help avian visitors fuel up for migration or make it through a tough winter. It can also provide great opportunities for wildlife photography and observation. But it’s not enough to put out a feeder and fill it regularly. You need to clean it out, or you risk inadvertently causing the birds that visit to get sick. The same goes for birdbaths. Some of the more common diseases that birds can spread through feeders include house finch eye disease (the colloquial name for mycoplasmal conjunctivitis, which can infect more than just the bird for which it’s named), salmonellosis (caused by salmonella bacteria), aspergillosis (a fungal respiratory disease), avian pox, and avian flu. If you see a sick bird or one you suspect died from a disease outbreak, don’t pick it up or try to treat it yourself. Instead, contact your local wildlife rehabilitator or call the National Wildlife Health Center for instructions. To prevent the spread of...