How birds benefit from bird feeders:
"Traditionally, it was thought that feeding birds was not very important and maybe only done during the cold winter months. However, because of the spread of urban development, many sources of food & water for birds have been lost.
Over time, roads, parking lots, retail centers and other results of urbanization, have drastically impacted the ability of wild birds to find sufficient sustenance, even during the more bountiful spring & summer months. Using bird feeders during all the various seasons helps replace these lost sources of food and enhances bird populations.
In the spring time, birds are migrating & nesting and need as much good nutrition as they can get. In addition, feeding birds is a great way to attract various species to your backyard for observation. And as a side benefit, birds provide a “green” way of insect control as many seed eating species also consume “garden/lawn harmful” insects in great quantities."