Wild deer numbers have reached record levels in Scotland - with a devastating impact on parts of the countryside, according to a report.
The report said numbers of red deer had trebled
The study was commissioned by conservation groups WWF and the Royal Society for the Protection of Birds.
It blamed deer for a rising toll of road accidents and claimed they were affecting forestry, agriculture and the rural economy.
The organisations are calling for action to stem the increasing numbers.
They said the report showed that wild deer were having an ever-increasing impact on the countryside.
In woodland, over-grazing means young trees are destroyed.
The organisations said that Scotland was likely to be the location for a high proportion of the road accidents involving deer in the UK.
Nine people died on Scotland's roads and 10 were seriously injured during a five-year period.
Pete Mayhew, senior conservation manager for RSPB Scotland, said: "Deer are a public asset and they have an important place in a balanced landscape.
"People love to see deer in the woods and on the open hill, but the three main species of deer in Scotland - red, sika and roe - are at their highest numbers since the war and are still increasing.
"This rising number has to be addressed as it has implications for everyone who works, lives and enjoys the wildlife in rural Scotland."
The conservation groups said part of the problem was that sporting estates had a vested interest in not culling too many deer.
They also argued that the Deer Commission did not have sufficient powers and resources to deal with the situation.
The report said that red deer numbers had trebled since the body was set up to control the animals 44 years ago.
Simon Pepper, the director of WWF Scotland, said: "It is up to the Scottish Executive to take responsibility for this issue and equip the Deer Commission to tackle the problem more effectively.
The Deer Commission dismissed the claims
"Otherwise the wildlife and rural economy of the future will be much poorer, and deer will be regarded more as a pest than a majestic asset of which Scotland should be proud."
However, the commission described the claims of rising deer numbers as a "gross generalisation".
It said there had been a number of changes in the way that deer numbers are calculated over the years.
The Scottish Executive said it was helping the commission to press ahead with co-ordinated action to achieve early progress on important environmental and road safety objectives.
The Scottish Landowners Federation said there were many reasons for rising numbers of the animals, such as milder winters.