Predators have been returning to the Cairngorms Connect area over the last few decades. For example, there are now 11 species of regularly breeding raptor, including golden eagle, white-tailed eagle, hen harrier, peregrine and merlin. Mammal predators include red foxes and badgers, and pine marten populations have increased significantly. Within the same area there are prey species that are threatened, such as capercaillie. To study this changing community of predators, and the implications for prey species, a group of organisations and individuals is collaborating in the Cairngorms Connect Predator Project (CCPP).
The aims of the Cairngorms Connect Predator Project are:
Forestry and Land Scotland
The University of Aberdeen
Highland Raptor Study Group members
This is the main, ongoing study in the CCPP, which is being carried out by PhD student Cristian Navarro.
The composition of the predator guild is changing rapidly in the area of the Cairngorms Connect; the previously absent pine marten is now widespread, jays have colonised the forest and northern goshawks and golden eagles are thriving. Factoring in these, often protected, recovering predator populations when planning the management of threatened prey species such as the capercaillie, constitutes a novel challenge for wildlife conservation in Scotland.
While higher abundances of certain species of predators could increase predation pressure upon already vulnerable prey species, predators are known to interfere with each other. Examples of this are eagles known to prey on foxes, foxes to kill martens and weasels or goshawks to prey upon smaller raptors. Consequentially, the restoration of predator interactions has the potential to locally modulate predation pressure and thereby benefit populations of prey species.
Quantitative knowledge of the strength and type of these interactions in newly enriched assemblages of species that could inform wildlife management is scarce. This PhD is working to bridge this gap and understand the role of these interactions in structuring predator communities, their drivers, and the implications for prey. This will be achieved through, among other tools, the use of the latest genetic methods to find out what foxes, martens and badgers are eating, and a large camera trapping effort.
Voles are a key prey item for many of the predators in the CCPP area. However, vole populations go up and down over the course of several years. Therefore, it is possible that in years of low vole numbers, predators will focus on other prey species and perhaps vulnerable species like capercaillie and red squirrels. Therefore, it is important to monitor vole populations to understand what is going on within the ecosystem.
Capercaillie are threatened with extinction from Scotland and therefore the population is closely monitored in the CCPP area. All leks are counted each year.
This is carried out on a largely voluntary basis by members of the Highland Raptor Study Group. This work includes some nest clearances at the end of the season, which give an indication of the prey species eaten by raptors.
To protect and enhance the habitat within the Cairngorms Connect area, it is important to control deer numbers; given that large carnivores like wolves are not present. When a deer is shot, the intestines are removed immediately and left on site. This provides many predators with a lot of food, which could have implications for their populations and their impact on vulnerable prey species. This study deploys camera traps at grallochs to understand what predators consume grallochs and how all the predator species interact.
Kenny Kortland, Wildlife Ecologist, Forestry and Land Scotland
Cristian Navarro, PhD student, University of Aberdeen, School of Biological Sciences
Jeremy Roberts, Programme Manager, Cairngorms Connect