If you’re a bird lover and have feeders in your yard, you may have noticed some sick or sluggish birds on the perch. Over the past several months, the bacterial infection salmonella, the same disease sometimes found in poultry, has afflicted many flocks of songbirds across New England and parts of the Midwest. As Vermont Public Radio’s Nina (Ny-nah) Keck reports, backyard bird enthusiasts can help to control the epidemic.