Red deer numbers are rising so fast that other wildlife is at risk, a study has warned.
The report said red deer were threatening other wildlife
Deer numbers have rocketed to 400,000 - to the delight of the tourist industry and shooting parties.
But ecologists have warned the boom is threatening woodlands, which are important habitats for more vulnerable species and native plants.
Fears about the effect of the deer population have been aired in the new edition of the BBC Wildlife Magazine.
Damage has reached such a serious level that Scottish Natural Heritage (SNH) has produced a long list of areas where it will miss government targets for improving nationally important nature reserves.
Conservationists at SNH have already pulled out of two reserves - in Wester Ross and Angus, where damage is out of control.
Warnings had already been issued about the soaring deer population
The population explosion has been caused by recent mild winters and the deer's lack of a natural predator.
Estate owners have insisted culling is expensive and sources in the US have cast doubt on suggestions to reintroduce wolves in an effort to curb the deer boom.
Other options include imposing fines on landowners who fail to meet cull targets or changing the red deer's legal status so that anyone with a proper licence is allowed to shoot them.
A report in 2003 discovered that wild deer numbers had reached record levels in Scotland - with a devastating impact on parts of the countryside.
The study was commissioned by conservation groups WWF Scotland and the Royal Society for the Protection of Birds Scotland.