Most feeder stations have at least one “workhorse” feeder. Quite often that feeder is a hopper feeder. This type of feeder can vary widely in design. From simple open trays to covered trays (fly thru feeders) to hopper feeders with some degree of seed storage, these feeders do not exclude any birds. These are often the only types of feeders that larger birds like Blue Jays, Mourning Doves and Northern Cardinals can feed from with relative ease. I think birds feel safe at these feeders because of the open viewing of their surroundings.