Report on capercaillie breeding success in Scots pinewoods in Strathspey

The Scottish capercaillie is of high conservation concern as the population has declined to 1,000-2,000 birds since the 1970s. Strathspey remains the stronghold with around 75% of the Scottish population. However, capercaillie productivity varies across the region.

The report –‘Correlates of capercaillie productivity in Scots pinewoods in Strathspey’ – is the result of a partnership comprising SNH, RSPB Scotland and the Cairngorms National Park Authority (CNPA).

The report reaffirms the complex relationships between the success of capercaillie in rearing young and habitat structure, predator activity and weather during the egg-laying and brood rearing period.

Some elements have been found before, notably an association between poor capercaillie breeding success and wet weather in June when nesting females have dependent broods.

Others, including a weak association between breeding success and a measure of pine marten activity, need to be explored further in order to fully understand the relationship.

One new finding was that blaeberry leaves (a key food item) had a better defence against herbivores through their chemical composition in old-growth Scots Pine forest than in younger plantations.

Adult capercaillie and chicks depend heavily on blaeberry leaves and their associated insects as food. However further work will be needed to test this finding and assess whether forest management could help to increase the quality of blaeberry in forests for capercaillie.

Sue Haysom of SNH said: “This report improves our understanding of the complex relationships between weather, habitat, predators and capercaillie breeding success and how these factors vary across key woods in Strathspey.”

Justin Prigmore of the Cairngorms National Park Authority (CNPA) said: “Strathspey is the most important area in Scotland for the species and is the only area where numbers have remained relatively stable. It is essential that we do all we can to ensure their long-term survival here. This work shows that it is a complicated picture but helps direct where we need to focus effort for the future and will further inform the Cairngorms Capercaillie Framework which is working across this landscape scale.”

Ron Summers of RSPB Scotland said: “This study of data amassed over 10 years has helped further our knowledge of the various factors that impact on capercaillie breeding success in Strathspey. As the last stronghold for capercaillie in the UK we need to understand why their productivity varies significantly so markedly across this area. Capercaillie numbers have decreased rapidly since the 1970s and this report will help inform our future conservation efforts to save these magnificent birds in Scotland.”