With its magnificent branching antlers, russet-brown coat, physical strength and speed, the red deer has become one of Scotland’s most popular and enduring natural icons.

It thrives in the Highlands and Islands, where forests and secluded glens have allowed numbers to surge in recent years.

But the deer are also voracious eaters and their breeding success is creating major problems for efforts to boost plant and tree life north of the Border.

A coalition of conservation charities is now warning a step-change is needed in efforts to control the population after staff at wildlife agency Scottish Natural Heritage (SNH) admitted it would probably miss key biodiversity targets because of the problem.

The conservation bodies have also called for a greater sense of urgency to protect woodland and peatland, and says SNH needs greater powers to deal with landowners who do not play their part.

SNH yesterday submitted a report to Scottish Government ministers on its progress in tackling rapidly growing red deer numbers.

It is estimated the main Highland range in Scotland now has about 400,000 of the animals.

This compares to fewer than half that in the 1960s.

The deer browse on young trees, stopping them becoming established, and also devour plants and shrubs.

Conservationists say woodlands, a vital part of the strategy to combat carbon emissions, will never recover unless numbers are cut dramatically.

In 2016, when it last reported to Holyrood on the state of deer management, the agency was criticised by MSPs for not taking a tough enough line against landowners who let deer numbers grow.

It has been working hard with voluntary deer management groups, made up of significant landowners in each area, to turn things around since then.

The latest report says significant progress has been made in planning, with some signs of improvement on the ground.

But it adds: “Three of the five Scottish Biodiversity Strategy Route map 2020 targets in which deer management has a role are unlikely to be delivered.

“The native woodland condition and restoration targets show insufficient progress and should be a priority for future focus.”

Four of Scotland’s biggest nature charities – the John Muir Trust, RSPB Scotland, the Scottish Wildlife Trust and Trees for Life – have called for further action following the report’s publication.

They welcome improvements in the way deer management groups run but in a statement warn: “A step change is needed if climate and biodiversity targets are to be met.”

Duncan Orr-Ewing, from RSPB Scotland, chairs a special Deer Task Force made up of the four groups.

He said: “We welcome the report’s findings that the majority of land managers are complying with the basic requirements of the Deer Code, and acknowledge the positive leadership of SNH within the constraints of a voluntary system.”

But he added: “It’s also clear from the report that much more needs to be done.

“Across our upland landscapes in particular, high deer impacts and other grazing pressures are damaging peatlands and halting woodland regeneration and expansion.

“These issues are closely connected to meeting the obligations of the Scottish Government’s climate emergency and halting drastic biodiversity decline. We need a sense of urgency to protect and restore our woodlands and peatlands.”

Robbie Kernahan, SNH’s Head of Wildlife Management, said: “We welcome the significant progress made by landowners and managers... There are still challenges ahead – but this report shows important improvements. Enriching nature is long-term work and we expect to see more tangible benefits in the coming years, adding to Scotland’s biodiversity and helping tackle climate change.

“We continue to work with environment groups and deer managers to strengthen and develop approaches to manage deer across Scotland ... SNH is committed to taking a lead role in further work to ensure Scotland deer are sustainably managed.”

Richard Cooke, chair of the Association of Deer Management Groups, said the report recognised that deer densities are declining due to higher culling levels, and that management groups are helping restore woodland and peatland.

He said: “The climate emergency is a matter for us all and DMGs are particularly well placed to make a contribution to Scottish Government net zero carbon targets ... While recognising that many challenges lie ahead, the red deer sector has shown that it can respond to changing circumstances.”