SCOTLAND’S most threatened bird, the capercaillie, is to be bred at a wildlife park in a bid to help build a back up population of the disappearing species.

The popular native bird - whose Gaelic name translates as the “Horse of the Woods” - was reintroduced to Scotland in 1837 from Swedish stock after becoming extinct the previous century.

A steep decline in recent years has seen the largest member of the grouse family included on the “red-list” of species of highest conservation concern.

The latest national survey revealed there may be as few as 1,114 individuals, restricted to only a few areas, mostly in Strathspey.

The birds are also occasionally found in the Highlands, Moray, Aberdeenshire and Perthshire, but Strathspey holds about 83 per cent of the remaining population.

Two pairs of capercaillie have now been introduced to the Royal Zoological Society of Scotland (RZSS)’s Highland Wildlife Park in Inverness-shire.

The move is designed help create a strong captive population to potentially safeguard the future of the species, which continues to be threatened by habitat destruction, predation, shifts in weather patterns and collision

with fences.

Doug Richardson, head of living collections at the wildlife park, said: “The population of the ‘horse of the forest’ is once again on a downward spiral for reasons that are not especially clear, with everything from predation by the recovering pine marten to collision with deer fences being suggested.

“The majority of the birds still found in Scotland are in Speyside, the region of the Highlands which also is home to RZSS Highland Wildlife Park.

“The species was reintroduced to the UK using birds from Scandinavia following the first extinction in the 18th century, and it is not inconceivable that a second reintroduction might be required at some point in the future, at least to augment existing pockets of capercaillie.

“It is our intention to build on the success of other breeders and rear behaviourally robust chicks that could, if required, be released back into the wilds of Scotland.”

The capercaillie is the world’s largest grouse. Males - unmistakable with their slate grey plumage, blue sheen head and bright red eye ring - can reach around 90cm in length and 14lbs in weight. Females are smaller with

brown and chestnut-red feathers and fan-shaped tail.

There were around 20,000 birds across Scotland in 1970, but the most recent survey conducted by RSPB Scotland during winter 2015/16 revealed just 1,114 birds - around half the size of the population in 1993, when the first survey estimated there were 2,200.

Around 83 per cent of the remaining capercaillie are found in Strathspey, where the population is crucial to their long-term survival.

Capercaillie breeding success is adversely affected by high rainfall in June, when the chicks hatch, and predation.

Wetter summers have become more frequent and the small size and fragmented nature of the forests the birds inhabit allow easier access to predators.

There is also growing evidence that human disturbance is causing capercaillie to avoid using large areas of otherwise suitable woodland, limiting the potential for population recovery.

Despite their size, capercaillie are fairly elusive, often sitting quietly in pine trees or on the forest floor.

In spring, however, they can be seen gathering at communal “leks” -- the males’ courtship display in the hope of attracting a mate.

The males have an amazing song they use at leks which is a series of “cliks” ending in a loud “pop”.

They are also very aggressive towards rival birds and fighting at leks is common.