For decades, as their numbers declined relentlessly, it was feared Scotland’s red squirrels were on an inexorable path to disappearing.

But fresh hope has been sparked after a survey indicated the iconic rodent’s population in many parts of the country remained stable last year.

The positive finding in the Saving Scotland’s Red Squirrels (SSRS) annual report for 2019 is due to the animal’s non-native grey cousin being pushed out of several areas, researchers said.

Scotland is home to 75 per cent of the UK’s red squirrels but their numbers have fallen to just 120,000, largely due to the spread of greys.

SSRS say the latest survey results are “worth celebrating” regarding the species’ future in the south of Scotland, including Dumfries & Galloway, the Scottish Borders and parts of Ayrshire and South Lanarkshire.

In the North East, it found that a “notable decline” in grey squirrel territory had continued, while, elsewhere, some survey sites have gone from being “grey only” to “red only”. And in the south of Scotland, survey sites reporting red squirrels remained between 51-52% in 2019.

But, encouragingly, sites with greys fell from 60% to 51% while the number of sites with only reds increased from 29% to 34%.

Welcoming the results, Dr Mel Tonkin, SSRS project manager, said: “The small changes in favour of red squirrels in the south of Scotland are certainly promising, but survey results can fluctuate from year to year and we will need to gather more data in future years to determine a definite trend.

“For now, we can say that red squirrel distributions in the region are stable.

“This is worth celebrating, and it is only possible thanks to ongoing work by volunteers, land managers and many others.

“However, we need to keep up the good work to hold onto our reds in the area and fend off the widespread grey squirrel threat.”

Dr Tonkin added: “The overall trend is also looking very positive in the North East and Central Lowlands.

“Although the 2019 results showed a small change in favour of grey squirrels when compared to the previous year, overall there has been a significant shift in favour of red squirrels since the surveys began, currently occupying 75% of survey sites. Focusing in on the Aberdeenshire results, grey squirrel populations have continued their retreat and are now largely limited to Aberdeen City.

“Here, city-residents have been reporting red squirrels turning up in increasing numbers of parks and gardens.”

Although red and grey squirrels can live side by side for a short period of time, greys will typically replace reds in most wooded landscapes within a few years unless efforts are made to reduce their numbers.

When squirrelpox is present this process can be far more sudden and rapid -- an infected red squirrel population can be wiped out within weeks.

SSRS, led by the Scottish Wildlife Trust, surveys squirrel populations using feeder boxes placed in the same areas of woodland each spring.

When a squirrel visits a feeder box, a sticky tab collects some of its hair, which can then be identified under a microscope.

The findings enable the National Lottery-funded project to evaluate efforts to reduce grey squirrel numbers and halt the decline of red populations in these areas.

The spring survey has been carried out in project regions in the north of Scotland since 2011 and in the south since 2013.

In recent years, results indicated that red squirrel populations had stabilised following several decades of decline. In some areas, pine martens have been used to control grey numbers, providing an additional boost for the red population.

The 2020 spring survey has begun. Through March and April, more than 180 volunteers will monitor feeder boxes. Volunteer Martin Hayes has monitored boxes at Glentress in the Scottish Borders for several years as part of the survey.

The most recent results show his site changed from “grey-only” to “red-only” for the first time.

He said: “After a number of seasons of detecting greys only, it’s great to see the area’s red squirrels finally getting a look in. “This year’s spring survey is going well so far, and as usual taking part makes a good walk in the outdoors even more enjoyable.”