They are among Loch Lomond's most popular and enduring attractions.

The goats of Inversnaid on the banks of the beauty spot's shores are said to have helped shelter Robert the Bruce as he fled his enemies – and to hold a valuable genetic record of an ancient breed.

But now the area's conservationist landowner, the Royal Society for the Protection of Birds (RSPB) has caused controversy by demanding they be shot.

The proposal has sparked a backlash from local people, tourist operators and goat experts.

Most of the herd on the charity's 2000-acre Inversnaid nature reserve on the east shore of Loch Lomond, through which runs the West Highland Way, is to be shot to protect woodland.

The RSPB says it has no choice after Scottish Natural Heritage (SNH) told it a woodland SSSI – a site of special scientific interest – in the reserve was in decline, and goat browsing was blamed.

Opponents say the cull, taking the herd of more than 60 down to just 30, is too severe and could damage tourism. The British Feral Goat Research Group fears the herd could die out as a result.

The local Strathard Community Council believes the RSPB has not adequately recognised the goats' importance.

It told the society: "The historic Inversnaid goats need protection too, in order to ensure that the herd continues to be viable."

The council carried out a survey of local people on the issue. Council chairwoman Fiona McEwan said: "We don't believe this widespread slaughter of goats near Inversnaid has been properly justified or planned by the RSPB, and want to ensure the long-term future of these goats is protected so the important and historic herd remains viable. There is great concern from local people and businesses, and this feeling is supported by the wider community."

She added: "Goats have co-existed with the trees and vegetation on this terrain for centuries – they are the symbol of Inversnaid, and a highlight for people who visit there and the 50,000-plus walkers on the West Highland Way every year.

"We wonder whether people who join the RSPB after seeing its 'Love Nature' campaign suggesting it wants to 'keep nature amazing' realise killing goats is one of the ways that the RSPB spends its money?"

Ecologist Dr Shirley Godyer from the goat research group said the Inversnaid goats have many characteristics of the now-vanished British primitive goats, and are a valuable genetic resource.

The reserve contains Bruce's Cave, in front of which the Inversnaid goats are said to have lain down to deter English troops from entering and finding Bruce after his defeat at the battle of Dail Righ against the English allies, Clan MacDougall of Argyll, in 1306.

Dr Godyer said: "There is a really strong historical and cultural aspect to this herd with the Robert the Bruce links, something that local people love and that can be used to great effect to promote the area.

"They certainly shouldn't be shooting this many goats. It has been a very hard winter and a harsh spring, and mortality rates are likely to have been quite high. Taking the numbers down to 30 is a bit low: it isn't a sustainable population if we get further bad winters. I would prefer to see about 50 left."

Both she and the council suggested moving the goats instead, and she added: "This cull is a very blunt tool."

Neil Wells, whose firm owns the Inversnaid Hotel next to the reserve, said: "Leaving 30 feels like a very low number to maintain the herd – 50 or so feels more like it."

Rob Coleman, area reserves manager for the RSPB, said: "What we're doing is establishing a level so that the goats and deer are in balance so the woodland can thrive and the goats and deer can too. If we do nothing, the goats will continue to expand. If we stop controlling goats and deer too, the woodland would disappear eventually.

"We have to focus on the designated habitats [the SSI]. That's the priority rather than the goats, but we don't want to see the goats disappear and what we are doing is managing them to a level that we feel is acceptable."

He said relocation had been found not to be feasible.

Richard Baynes