There are no natural predators of deer in Britain. Therefore, to maintain a stable and healthy population of deer a cull of some of them is required each year. This is not random however, and a deer stalker will have carried out a population count/census to determine the age and sex profile of those to be culled. So then during the correct deer season, barren, genetically odd or very old animals are taken. After that selected animals resulting in a balanced pyramid profile with a few healthy older animals of each sex at the top with increasing numbers of each sex down to the yearlings at the bottom.
The males with outstanding antlers are sometimes referred to as trophy animals, and as part of the cull, can be shot as part of a purchased sporting package to bring income to help with the management of the deer population as a whole. If population reduction is required, more females will be culled. If a population increase is required, only a selected few will be culled.