Hi
I have a sparrow hawk hunting in my garden on a regular basis - have a healthy sparrow population as well as a good sprinkling of various other species of garden birds and drop in's e.g. goldfinch, tits. You haven't provided the natural cover attributes of your garden - maybe the lack of cover has meant that your regular visitors have scarpered due to the threat in the short term. As sparrow hawks are opportunists so are all bird species when looking out for a meal. Both will be back and be rest assured your garden will be thriving once again - both need to eat to survive. Think of ways you can introduce cover or put in a tall structure such as a garden wooden post - by observing the behaviour of my sparrow population I have noticed that whilst some are using the feeder others are keeping watch for the sparrow group.