conservation efforts designed to save Scotland's most southerly capercaillie population seem doomed to failure, according to experts.

The remaining few clusters of the largest member of the grouse family in the Trossachs and Argyll have steadily declined over recent decades. The last is centred on some of the Loch Lomond islands, but there are only a few birds left and they are not breeding.

The nearest strong population is now in the Cairngorms National Park, well beyond the distance that capercaillie will travel to search for territory or a mate, and this leaves any remaining birds on the islands isolated, with no realistic prospect of being joined by individuals from elsewhere.

Alan Bell, natural heritage manager for Loch Lomond & The Trossachs National Park Authority, said that despite all efforts the simple fact was that no new birds are moving to the islands to breed with the resident birds.

Anne McCall, RSPB Scotland regional director, said: "The loss of the iconic capercaillie from the Loch Lomond islands is a real disappointment. Combined efforts to reverse declining population trends have not succeeded and this situation highlights the pressing need to take fast, targeted action wherever possible.

"As such it is increasingly important that resources are found to support work elsewhere for our remaining capercaillie populations if they are not to suffer the same fate."

The population of capercaillie in Scotland and across Europe is under pressure. A run of wet summers has seriously affected chick survival. Meanwhile predation, loss or fragmentation of habitat, collisions with deer fences, and human disturbance are all taking their toll.

Long-running efforts by Loch Lomond & The Trossachs National Park Authority, Scottish Natural Heritage (SNH), RSPB Scotland and local landowners have not been able to halt the decline.

The last national survey in 2009-2010 showed 80% of the UK population of capercaillie was estimated to be the Cairngorms National Park, with the vast majority of them in Strathspey. Numbers there currently appear stable.

The organisations working to protect capercaillie in Scotland are now advocating a pragmatic approach to targeting resources where they will be most effective in maintaining viable populations. This will be in the likes of Easter Ross, Strathspey, Moray and Nairnshire, Deeside and Donside, and Highland Perthshire.

Alan McDonnell, of SNH, said: "A lot of people and organisations have worked for many years to help the population of capercaillie on the Loch Lomond islands, but we need to face the facts about this increasingly isolated group of birds.

"As things stand, our resources are focused on preserving the core populations in the north of the country."

Meanwhile, Scotland's gamekeepers, often accused of illegal persecution of birds of prey, say the significance of their stewardship of grouse moors in aiding the conservation of golden eagles is too often ignored.

They say the areas which are looked after by gamekeepers for grouse shooting also provide the necessary food supply for the golden eagles.

The Scottish Gamekeepers Association says it takes the issue of persecution seriously and is addressing it, having recently expelled four members for wildlife offences.