Capercaillie are one of Scotland’s most iconic birds but their population here is in serious trouble. Much has been written about the many factors that impact them; the species has already gone extinct once and been re-introduced in the 1830s.
So the recent Review of Capercaillie Conservation and Management (NatureScot report) and actions proposed in it are very welcome and we are in broad agreement with much of what it says. In this blog, we’ll be taking a look in more detail at the report’s findings, our response to them, and the work that we at RSPB Scotland have been doing to help these majestic birds to try to ensure a long term future for the species here.
Capercaillie and RSPB Scotland
RSPB Scotland has been involved in capercaillie conservation for over 30 years through our management, monitoring and applied research at Abernethy, carrying out national surveys, counting leks and employing staff who deliver advice to land managers and help them access grants and deliver on the ground improvements.
We have worked with 25 private estates and statutory partners on several large conservation projects (the Capercaillie LIFE project, Species Action Framework and the current Cairngorms Capercaillie Project) funding habitat management, fence removal and marking, predator control and reducing disturbance for capercaillie.
NatureScot Report recommendations
Capercaillie are impacted by many factors including habitat loss leading to fragmentation, reductions in habitat quality, collisions with fences, cold and wet Junes, human disturbance, and predation. All of these are factors that affect the species across Europe including in Scotland.
The NatureScot report recommends four options that are ‘likely to have the greatest immediate positive impact on the population’ in Scotland:
Whilst mostly agreeing with the findings of the report, we do have some concerns about the over-emphasis of the importance of evidence underpinning predation and predator control, and under-emphasis of the impacts of climate change and habitat management. We believe these need to be addressed when deciding on actions to take forward to help capercaillie.
There are some key scientific papers missing from the review especially in relation to inbreeding, habitat management, and fence marking, which would add important further detail. Consideration should also be given to any relevant ongoing research but especially the work of the Cairngorms Connect Predator Project, the large-scale field layer management trials at Abernethy, the genetics work of the Cairngorms Capercaillie Project and research to develop new ways of monitoring breeding success.
Image credit: Ben Andrew
Several studies have demonstrated that diversionary feeding of predators which involves placing deer carcasses out weekly during the egg and chick stage of the breeding season can improve breeding success for a range of species. This includes a long-term study showing benefits for capercaillie and black grouse in Norway.
RSPB Scotland in partnership with Cairngorms Connect and Aberdeen university is hosting a PhD trialling diversionary feeding to reduce mammalian predator impacts on capercaillie and initial results using dummy nests (of chicken eggs) are promising. The results of this PhD study should be important for informing how best to use diversionary feeding to improve capercaillie success.
Both the impact of predators and predator control in conservation are understandably emotive subjects. Predation impacts on species of conservation concern are complex, affected by habitat quality, fragmentation, availability of other prey and interactions with other predators.
While some studies have shown that very intensive predator control will benefit woodland grouse, including capercaillie, such intensive effort is rarely sustainable, particularly over a large area and long-time scales.
Lethally controlling vertebrates is sometimes necessary for conservation of some species and since 2014 RSPB has published figures on numbers of predators controlled on our reserves.
RSPB is a science-led organisation and will only carry out vertebrate control when the following four criteria are met:
The 2018 review of predation and wild birds highlighted that the UK has high densities of foxes and crows and that there is a need for research to understand how landscape-scale habitat management could be used to provide longer-term sustainable solutions to reduce impacts of predators on species such as capercaillie. This would significantly reduce the need for continued expenditure of huge resources on lethal control.
Our Abernethy nature reserve, is trialling such an approach using long-term, large-scale habitat restoration as part of Cairngorms Connect, rather than intensive predator control that cannot be sustained. Despite ceasing fox and crow control in the last five years at Abernethy, the number of capercaillie males counted at leks has remained stable since 2013, and the 2022 count is the highest we have seen for a decade.
RSPB Scotland would only consider restarting predator control at Abernethy if it meets the four tests set out in our vertebrate control policy (above). Even where fox control may be appropriate or desirable, we strongly believe there should be a presumption against the use of dogs for driving foxes in capercaillie woods due to disturbance caused and the use of snares which poses a mortality risk to capercaillie.
Much of the evidence for fox and crow predation impacts on capercaillie cited in the NatureScot report comes from studies that are more than 20 years old. Since then, the predator community in these parts of Scotland has continued its recovery – often from the impact of significant and sustained persecution by humans – and the suite of predator species present now is far more diverse than 20 to 30 years ago.
RSPB Scotland’s vision for Abernethy is a forest with a sustainable capercaillie population in the presence of a more naturally functioning assortment of predators that includes pine martens, badgers, foxes, goshawks and eagles and in the future, missing and under-represented species.
Interactions between predators are a critical part of the natural system. Emerging studies of the interactions between predators in the Cairngorms, suggests that the presence of larger predators likes foxes and badgers influences the activity of the smaller predator, pine martens. Similarly, goshawk and other birds of prey will predate crows and inhabit old nests sites and interact with each other as well as predating on mammalian predators. Interactions between predators are complex which makes it difficult to study or predict what the impacts of removing or excluding one species has on all the other species (both predator and prey) in the system.
The interaction between predation and habitat quality and connectivity is one of the things we feel is not given prominence in the NatureScot review. Some studies conclude that whilst predation limits capercaillie populations where habitat is poor, where there is good habitat quality the impact of predation can be mitigated. Productivity can be high, despite high predator numbers.
Maintenance or restoration of habitat quality should always be the primary conservation objective. At RSPB Scotland’s Abernethy nature reserve we have combined deer control with promoting natural tree regeneration; we have introduced cutting and cattle grazing to replicate lost herbivore species in the forest. These measures break up long vegetation, increase the abundance and availability of insects and boost tree regeneration. Looking forward, funding mechanisms need to be available for land managers to improve habitat across the capercaillie range.
The roll of wet weather in June is also not fully acknowledged in the review. In years when the June rainfall exceeds 100 mm, the breeding success at some sites is usually zero. So, it is possible that even if other factors such as predation can be managed, a wet June has an over-riding influence, and if these are increasing in frequency, this will have a bearing on the population.
We realise that there are differing opinions and approaches to predator management that could be adopted within the capercaillie range with some keen to use emerging non-lethal methods such as recovery of a more natural predator community and diversionary feeding whilst others will be keen to continue with lethal predator control. At Abernethy, RSPB Scotland will continue habitat restoration and diversionary feeding whilst we understand that other land managers will use these other methods to help capercaillie.
However, we think it is essential that all approaches are monitored carefully to allow comparison of the differing approaches in the future. This is vital if we are to have a science-led approach to capercaillie conservation to deliver the best chance of helping the long-term survival of the species. At a basic level, monitoring done via the national surveys could be informative for comparing capercaillie distribution and trends between land deploying different approaches to land and predator management over the coming years.
We believe that being able to measure capercaillie breeding success is important ,especially if we want to understand the success of specific conservation interventions designed to increase breeding success.
Whilst brood surveys have traditionally been done using dogs to locate broods, we do not believe this a suitable method anymore. There are unacceptable risks in terms of disturbance and chicks being separated from their families and, at this low population level it can no longer detect an adequate number of broods and chicks with which to make annual comparisons of breeding success.
Therefore, RSPB Scotland in partnership with the Cairngorms Connect Predator Project are undertaking a large scale trial of a new and innovative way to provide a measure of breeding success by using camera traps placed at capercaillie dust baths that capture images of hens with broods. Although still in development this method of measuring productivity could be useful as a future way to track the productivity of capercaillie across the range but would require additional resources.
Image credit: Dave Braddock
Pine marten translocation
Our biggest concern in the NatureScot report recommendations is the translocation of pine martens from capercaillie forests.
The full results of the diversionary feeding study are yet to come but will further our knowledge of the success of this method in reducing the impact of pine marten and other predators on capercaillie.
We have doubts about the success of translocation in reducing local populations of pine marten. Pine marten are a highly mobile species, and likely to rapidly re-colonise any vacated high-quality habitat from neighbouring areas. Essentially, if we move one away another will likely take its place.
Whilst we will not oppose a closely monitored trial translocation under a research licence, this must follow IUCN guidance and the Scottish Code for Conservation Translocations, including consideration of where translocated animals are moved to and their welfare.
Pine marten are a protected species on Schedule 5 of the Wildlife and Countryside Act (1981). Populations are still recovering across Scotland after decades of persecution and these mammals remain absent from many areas where they previously were. This is why, we and other NGOs, called for its continued protection as part of a recent UK wide review of non-avian species protected under the Wildlife and Countryside Act and why we will not permit removal of pine martens from our landholdings such as Abernethy.
We are seeking re-assurance from the statutory agencies that there is no mission creep to recommend lethal control or translocation of other protected species. Despite their recovering populations, there is currently little or no evidence that badger or goshawk are significant predators of capercaillie in Scotland.
Although goshawk have been recorded specialising on woodland grouse predation in other parts of Europe, this has not been the case in Scotland. Corvids are the main prey item which may reduce nest predation. There is little scientific evidence to support badgers being a predator of capercaillie nests.
Image credit: Louise Greenhorn
We very much welcome the focus on creating refuges for capercaillie in the NatureScot recommendations. There is a growing body of evidence of the impacts of human disturbance on capercaillie. High road and track densities are associated with reduced use of habitat and these effects are more pronounced in woods with the highest levels of recreational use. Disturbance in this sense is effectively a form of habitat loss.
There is already provision within the Scottish Outdoor Access Code to protect sensitive sites and species:
Take care to avoid damaging the site or disturbing its wildlife, or interfering with its management or enjoyment by others. Depending on your activity, you might be requested to follow a specific route or to avoid exercising access rights in a specific area.
At Abernethy we make use of this provision every year by displaying signage between 1 April and 15 August asking people to keep to paths and that dogs must remain on a lead in capercaillie areas. The Cairngorms Capercaillie Project is already working with mountain bikers to re-route tracks from sensitive areas. This approach is very welcome, innovative and replicable but requires ongoing resource.
However, these measures are not enough to reduce disturbance. We support the creation and maintenance of capercaillie refuges in suitable habitat by closing and re-routing some access routes working with the local outdoor access forum and if necessary, through use of bylaws.
These recommendations were made in the 2015 Cairngorms capercaillie framework. There also needs to be a consistency of message and measures (e.g. around dogs and dates) across land managers and statutory bodies.
In the long term capercaillie need more suitable connected habitat because disturbance effectively reduces availability of suitable habitat and that can lead to fragmentation even within physically connected forest areas. In line with the Cairngorms National Park plan and ScotGov policy there needs to be continued emphasis on expanding and connecting up areas of Scots pine forest of natural character across Strathspey and seek to link to other areas to the north and east. This includes natural regeneration of woodland, removal of non-native species and planting where seed sources aren’t available. In the short term, reducing disturbance could open up more areas of forest as potential habitat for capercaillie.
We were very pleased to see the importance placed on removing or marking deer fences in key capercaillie areas by the NatureScot report. There are currently over 20km of unmarked deer fences within 1km of an active capercaillie lek and 58km in the 1-2km distance from lek zone.
In a long-lived species like capercaillie, population change is much more sensitive to changes in survival than changes in breeding success so any interventions that decrease mortality and increase survival, should be prioritised for resource and rolled out across the entire range.
Reducing deer densities to reduce the need for fencing, removing old fences where possible and clearly marking those fences that remain are probably the interventions that have the clearest and most robust evidence base for success.
Fence removal also has the added benefit of opening blocks of woodland to grazing and browsing by the remaining deer, which may have benefits in terms of field layer habitat quality which can become extremely tall and rank in the complete absence of grazing.
Looking forward
We agree with the report recommendations that short term action is needed urgently. At Abernethy we will continue large scale habitat restoration, through forest expansion and field-layer management and predator management through diversionary feeding.
Outside our reserves we accept that others will adopt different approaches. We propose that the different approaches are monitored properly to allow comparison and learning in the future to provide long term actions for capercaillie conservation and their survival in Scotland.
We hope that this approach undertaken across a large area by land managers will benefit not only capercaillie but also help restore diverse thriving forests home to many species.
Header image credit: Dave Braddock