Capercaillie conservation: what does the evidence tell us?

In recent months there has been more in the news about capercaillie conservation, and particularly the impact of predation on the vulnerable population in Scotland. In today’s blog, we look beyond the headlines at what the science and evidence tells us about capercaillie conservation, and the steps we are taking to tackle the threats to this iconic species.

Male capercaillie displaying at a spring lek in the Cairngorms National Park ©Neil McIntyre

There’s no doubt that the capercaillie population in Scotland is extremely vulnerable, and that the future of the species is at risk. Expert opinion in the 1990s was that capercaillie would be extinct by around 2010. All efforts to help the bird at the time ensured that this didn’t happen. We’ve been working with a wide range of land managers and partners for decades to try and protect and restore our struggling capercaillie populations and will continue to do so.

In 2021, we asked our Scientific Advisory Committee (SAC) to look at the reasons for the recent decline and make recommendations for further action to reverse it. High-quality science and evidence is at the heart of all of our work to protect, restore and value nature, and we wanted a thorough review of the research to guide our next steps.

Their report was published in 2022 and set out measures that could help reverse the fortunes of capercaillie. One recommendation was to reduce predation on eggs and chicks, alongside measures to limit disturbance and remove or mark fences. The report concluded that it was unlikely that any single measure would be enough to prevent further population declines.

After considering the report, our board set out what we would do in response, working with the Cairngorms National Park Authority. This includes:

• More investment to restore the capercaillie’s pinewood habitat on a landscape-scale and for the long-term.
• Survey work to better understand the size and impact of all predator populations that might be impacting on capercaillie – including crows, foxes and pine marten.
• A plan for further positive action, including reducing disturbance, increasing diversionary feeding of predators and marking or removing fences.

Some have asked why the lethal control of predators is not the key focus of this work. We know that managing the pressures of predation can benefit vulnerable prey species, and this is something that is already available as a conservation tool. For example, foxes and crows can be legally controlled to help capercaillie. Pine martens, however, are a protected species in Scotland and we need to better understand their recent spread to assess whether they are the cause of any ongoing capercaillie declines. We will be studying pine marten populations to help us get a better handle on their role in this complicated picture and will review the best course of action when we have this information.

Examination of the research also concluded there was uncertainty in how the range of predators – including foxes, crows and pine marten – would respond to lethal control. For example, one (or more) individual(s) may simply move into the space created by the removal of another, or reducing the number of one predatory species may lead to an increase in another, resulting in no overall benefit.

In addition, the SAC report concluded that removing predators was only likely to be effective over a large scale for many years. This policy would remove many native species from large parts of the Cairngorms and that is simply not compatible with achieving the outcome set out in the National Park Partnership Plan for a biodiversity rich National Park with better functioning, better connected and more resilient ecosystems.

Capercaillie face a raft of other issues, including weather events and disturbance. In addition, the birds need large areas of old pine woods to provide appropriate cover and food sources for both adults and young, and to provide more scope for the population to expand in the long-term. That’s why our focus is on regenerating woodland, as well as methods such as the legal control of foxes and crows during the capercaillie breeding season and managing public access when necessary.

Alongside this, we are also looking at other ways of reducing predation by all predators, such as diversionary feeding – where alternative food supplies are provided for a short period in the breeding season to reduce the likelihood of capercaillie predation. A study by the University of Aberdeen and partners on diversionary feeding of predators is nearing completion and has shown significant promise as an alternative.

While the outlook for our capercaillie has long been dire, some recent news offered a glimmer of hope. The results from this spring’s capercaillie lek counts showed an increase of 19 male birds – the first rise in eight years. While this is heartening, we cannot be certain that this equates to a similar increase in the total population, so we remain focused on taking the urgent and evidence-based action required to save this iconic species.