Because of the nature of a shotgun, wounding is inevitable and unavoidable. Shotguns are scatterguns and when the cartridge is fired, around 200 tiny pellets fan out from the barrel.
The range of a shotgun is only about 50 metres but in the excitement of the moment shooters often wound birds by firing out of range. It is difficult for shooters to judge distance in the split-second decision-making process required.
When birds are scarce, they will shoot out of frustration even though the bird is well out of range.
Shooters fire into flocks and can legally shoot in fog, mist, rain and windy weather as well as half an hour before sunrise and half an hour after sunset (when quite dark) which all contribute to high wounding rates.