Causes

A wide range of factors can influence capercaillie populations, listed below are some of the key issues that have been identified, for further information on these issues and how it is possible to minimise their effects please contact the Capercaillie Project Officer.

Multiple land ownership or unstable land ownership of core Capercaillie areas
Capercaillie meta-populations range and disperse over large areas that may involve a number of landowners. Actions for Capercaillie will need to be considered at this wider scale requiring liaison and co-ordination between landowners. Where land ownership is unstable, this can threaten long term conservation planning.

Lack of management planning and or background information
It is vital that works undertaken within the project are understood in the context of long-term conservation management and set within a formal management plan. Capercaillie requirements need to be considered within the management plans of other land uses including forestry, wider habitat conservation management and recreation addressing threats and opportunities. In many cases, a lack of background information on habitats and species is limiting the contribution of management planning to Capercaillie conservation.

Fence collisions
Collision with wire fences is perhaps the major cause of Capercaillie mortality - accounting for 24% of juveniles and 8% of adults. Internal woodland deer fences are particularly dangerous but all forms of fencing can be fatal. Marking fences with wooden palings or orange barrier netting can help to reduce collisions but a move away from reliance on fences to other forms of deer control is required.

Loss of eggs and chicks to predators
In some circumstances, chick predation by crows or foxes can add significantly to breeding failure. Changes in land use, fragmentation of semi-natural habitat and a reduction in game keepering has led to higher current levels of predator species than previously. This problem is exacerbated by the lack of good brood habitat that provides cover as well as food. Predator control needs to be combined with brood habitat enhancement and creation.

Overgrazing of habitat
Overgrazing of woodland flora by sheep and deer reduces the availability of brood habitat vegetation and the associated insect fauna that is vital to early chick development. High deer numbers also restrict the development of a multi-structured forest habitat and the potential for continuous-cover management.

Lack of brood habitat
Good quality brood habitat is generally scarce in many Scottish forests. This results in poor chick survival because of a lack of invertebrate food and a lack of cover to evade predation.
Loss of brood habitat to rank heather In more open woodland, heather can dominate the ericaceous species that provide the best brood habitat.

Loss and fragmentation of habitat
Extensive forest with areas of old growth forest tends to maintain higher numbers of Capercaillie than a fragmented woodland landscape. (While such forest has declined over the last century new areas of plantation forest have been created which could contribute better to Capercaillie metapopulation conservation if managed appropriately.) Woodland areas fragmented by agricultural land, and large clear-fell sites also support higher levels of predator species and deer which require control.

Lack of integrated conservation management and monitoring for pSCIs
Actions undertaken for Capercaillie conservation need to be linked to a programme monitoring the status of the species, associated fauna and flora and the condition of the habitat overall. This is a vital step to ensure the long-term effectiveness of the actions in reducing or removing threats and to refine future management.

Human disturbance of Capercaillie
Capercaillie may be disturbed by recreational users and their dogs, or by bird watchers interested in witnessing leks.

Lack of public awareness
There is a lack of public awareness of the need for Capercaillie conservation and of the habitat and species measures involved. This impacts both on the scope for promoting Capercaillie-specific management and the public finance and goodwill available for such work.

Lack of widespread technical understanding and support
Positive management for Capercaillie conservation in Scotland is relatively recent and while individual actions for species and habitat management are well known, there is a lack of technical experience and understanding, amongst foresters and keepers, of how to implement beneficial measures for this species.

Several factors have combinded to cause this disastrous decline:

• A lack of good habitat for feeding during the breeding season.

 

• Predation by crows and foxes.

 

• Fragmentation of its natural forest habitats.

 

• Fatal collisions (bird strikes) on deer fences.

 

• Cold and wet weather reducing breeding success.

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