The beauty of sunflower seeds without the hulls is twofold. For birds, there is the benefit that none of their precious energy reserves during the cold winter months is wasted opening the shells. For humans, there is no mess of shells accumulating under the feeders that eventually will have to be raked up and disposed of. Since the shells of sunflower seeds contain a component that is toxic to grass and will kill any grass that is growing around or beneath the feeders, this is an important factor for many people in choosing whether to offer sunflower seeds in or out of the shell.
Although the most species of birds prefer black oil sunflower seeds to all other sunflower seeds, shelled sunflower seeds attract even more species that aren’t equipped with the beaks to crack open the shells. Even species not usually associated with eating sunflower seeds – like robins, thrushes, mockingbirds, thrashers, catbirds, sparrows, bluebirds and other thrushes – will all consume the smaller chips or hearts that find their way to the ground.
But if there were only one reason to offer hulled sunflower seeds, it would be for the goldfinches that adore it. Goldfinches rank at the top of the list of the birds that most people want to attract to their backyard feeding stations and hulled sunflower seeds practically guarantee they’ll be regular visitors at any feeder stocked with them. In addition to the goldfinches, house and purple finches, chickadees, titmice, nuthatches, cardinals, grosbeaks, wrens, and woodpeckers all relish sunflower seeds out of the shell.