Most garden birds do not like to stray too far from cover; the general rule is that feeders should be sited fairly close to vegetation, to enable an escape route from a launching predator. However they should also be sited far enough from vegetation to prevent predators gaining access, and to enable all dangers to be visible. For example siting feeders far from the ground helps to avoid predators such as cats.
The RSPB estimates that there are around 9 million cats in this country, at 30 kills per cat each year, they kill 55 million birds each year. This figure is difficult to visualise, but close to the total British human population of 60 million!
In a statute of nature, a balance between predator and prey exists, whereby the number of predators fall if the prey species diminishes dramatically. However this balance is non-existant in the case of domestic cats, because they are not reliant on their prey for survival, so their numbers continue to increase even if the bird population disappears.
Cat owners can help to reduce kills by cats, so that birds and cats can live comfortably alongside each other:

