Some species are certainly more dominant at feeders than others – especially the larger species like Magpies, Rooks and Jackdaws, Starlings, and even the bigger of the ‘small’ birds such as Greenfinches and House Sparrows. Generally, the other smaller species don’t avoid feeders as a result, but they do change their behaviour – they’ll grab some food quickly and go rather than hang around, or they’ll visit your garden earlier and later in the day to get food and avoid the larger species in the process.
If you want to ameliorate things, the best thing to do is to provide more feeders in a variety of locations, allowing the smaller birds to visit the less-busy feeder(s) throughout the day. It’s better to have two half-full feeders in different parts of the garden, than one large and full feeder in one location as the latter will mean all birds have to visit the same location and will end up arguing with each other!
If your problem is with members of the crow family, some people use squirrel-proof feeders to prevent them accessing food, or tie two hanging baskets around the feeder creating a similar ‘dome’ that larger birds can’t get into.
