A REPORT investigating capercaille breeding success has been published by Scottish Natural Heritage.
The Scottish capercaillie – a huge woodland grouse – is of high conservation concern as the population has declined to 1,000-2,000 birds since the 1970s.
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.”