On a rocky ledge high above sea level and on one of Scotland’s most precious mountain landscapes, a tiny black and white visitor has settled into its summer home after a journey spanning thousands of miles.

Not unlike a blackbird with similar glossy black plumage, yellow beak and beady eye, over the years the small but mighty ringed ouzel has become a rare visitor to Perthshire’s highest mountain, Ben Lawers, renowned for its rich selection of alpine plants, dramatic beauty and a favourite destination for walkers.

Few who trek uphill might spot it or be lucky enough to hear its shrill call: just ten breeding pairs nest on the Perthshire slopes.

Regarded as a species at risk of being lost forever, the migratory visitors from warmer climes are an important barometer of conservation success – a cautious sign that one of Scotland’s earliest, and, perhaps, simplest habitat restoration efforts has been worthwhile.

Started in the late 1980s by the National Trust for Scotland when the devastating impacts of climate change and habitat loss were still to be fully understood, work at Ben Lawers to restore the landscape has taken root.

Using simple fences, near barren areas were excluded to troublesome sheep and deer that had chomped through saplings and destroyed montane scrub.

Allowed to regenerate, they now provide rich oasis habitats for rare moths, bees, butterflies and plants, some so unusual that the slopes are among the few places in the UK where they can be found.

While in a mammoth, back-breaking effort, hundreds of thousands of trees were planted.

Seeds from delicate alpine flowers identified as being at particular risk of being lost were collected, nurtured and the new plants they generated introduced, while tall herbs and wildflowers sprouted naturally on land where once was only short grass.

With pockets of habitat restored, black grouse numbers are thriving. Declining birds species such as whinchat have grown in number, alongside willow warbler, cuckoo, redpoll and twite, drawn by new areas to nest and forage. Fluttering overhead, the ringed ouzel – numbers have declined by 43% in the last four decades - are clinging on. Hopes grow each summer that more pairs might appear to nest, feed on berries from new crops of juniper bushes and pick at tiny bugs that have taken hold thanks to the regeneration work.

It's hardly happened overnight, but in fenced off areas of Ben Lawers, the highest peak in a range that includes seven munros and is regarded as one of the UK’s richest areas for alpine plants thanks to its perfect altitude and clay-like soil, nature seems to be slowly turning back the clock.

A key sign that life is returning came last year when several species of bee not previously found on Ben Lawers were confirmed during a painstaking survey across a vast area.

Several female Clarke’s mining bees (Andrena clarkella) were seen forging on willow catkins alongside the Morenish Woodland Trail. Hairy and with pollen baskets on their legs and abdomen, they are a widespread species in some areas but virtually unknown across the central Highlands.

A rarely seen female lime-loving furrow bee (Lasioglossum fulvicorne) also made a surprise appearance – unusual for a species previously only thought to appear in Scotland in the Cairngorms.

Nine of the 24 known species of British bumblebee have now been confirmed in the area, including the rare bilberry bumblebee (Bombus monticola) and the broken-belted bumblebee (Bombus soroeensis), raising hopes that more as yet unrecorded species might be lurking.

There are other success stories, says NTS senior ranger Helen Cole, confirming Ben Lawers a pioneer in habitat restoration and ground breaker in work to revive long lost montane scrub, prompting others to follow their lead.

“Habitat restoration worked started in late 1980s with two relatively small ‘exclosures’, which exclude the sheep and deer and meant we could restore natural plant habitat,” she explains.

“Just by fencing out herbivores, we got all sorts of associated plant communities; lots of tall, flowering plants started to appear.”

Around nine hectares were fenced off, allowing grasslands to recover. Woodlands needed a helping hand, she adds, particularly as early monitoring revealed some rare willows were in rapid decline.

“Some trees were okay, but others like willow and juniper are single sex plants and unless there are male and females close enough together, you are not going to get natural regeneration.

“We started collecting seed in early 1990s and instigated a programme of habitat restoration.”

The vision was to restore montane scrub, the mix of tough dwarf shrubs that survive above 600m – above the treeline and below the high montane heath. Once a natural feature of the landscape, generations of grazing meant hardly any remains in Scotland.

“There was no textbook on how to restore montane scrub,” says Andrew Warwick, another of Ben Lawers’ rangers, speaking during NTS’s latest Love Scotland podcast which focuses on work at the site. “It was the biggest and earliest of any type of montane scrub restoration.

“There was a worry when we fenced up areas that the grass would take over, but the exact opposite has happened, and grassland has been replaced by tall herbs.

“There was plume moth here, and the worry was that we might make that extinct. But it has survived that and been found in a much healthier state than before.”

Additional areas of fencing were introduced in 2000 after NTS acquired land in the Meall Nan Tarmachan area. The charity has also acquired some sheep grazing rights from farmers, again helping to keep herbivore numbers down.

The next step is more technical: the Trust is considering introducing cows to Ben Lawers, fitted with GPS collars to keep them within a ‘virtual fence’ where their kind of grazing can be particularly beneficial.

The result of the regeneration work so far has been a “significant change for the better”, says Helen. “We have started to pick up species of birds that we haven’t recorded before such as willow warbler, stonechat, whinchat and red poll.

“We’ve seen improvements in invertebrates, lots of mosses and beetles which provide food for a number of species of birds.”

Plants – which Ben Lawers is best known for – are also recovering.

Last week one Ben Lawers ranger tweeted their delight at finding a melancholy thistle – a tall plant with single purple flower - growing at a record height of 779m above sea level, flourishing “without the pressure of herbivore grazing”.

For some, it’s tougher. “There are some very rare alpine plants that grow in few other places in Britain. Some are stable but unfortunately three species have shown large declines, probably due to climate change. “All are associated with snow, and we have had much less snow over the years: snow pearlwort, mountain sandwort, drooping saxifrage.”

Reviving snowfall levels may be tricky, but an earlier NTS rescue operation to save Highland Saxifrage from being lost by introducing new plants grown from seeds taken from NTS’s site at Glencoe, is being looked at as an option for the species most at risk.

Restoring a mountain landscape may seem a tall order, but hopes are high that it can be done.

“It can be a little bit overwhelming at times, but we are quite driven,” adds Helen. “We have quite a lot of energy, and our focus hasn’t changed.”

The National Trust for Scotland’s work at Ben Lawers features on its latest Love Scotland podcast, www.nts.org.uk