BY CALUM CAMPBELL
Few creatures embody the untamed spirit of Scotland’s ancient woodland quite like the wildcat. Often referred to as the Highland Tiger, Felis silvestris is now recognised as Scotland’s most threatened mammal, with perhaps only a few hundred individuals clinging to survival in the remote glens. The fight to save this elusive predator from extinction has galvanised conservationists, culminating in a landmark reintroduction project led by the Royal Zoological Society of Scotland (RZSS) and NatureScot. However, the release of captive-bred wildcats into the Cairngorms National Park has ignited a complex and deeply sensitive debate regarding unforeseen ecological consequences—specifically, the potential threat to another iconic and critically endangered species, the capercaillie.
Recently, concerns were raised publicly regarding the discovery of capercaillie remains in proximity to translocated wildcats. As these anecdotal reports risked spiralling into rumour, direct clarification was sought from the Saving Wildcats partnership, the European-funded consortium responsible for the species’ recovery. A comprehensive response was provided by Helena Parsons, Outreach and Engagement Manager for the project, which offers a masterclass in scientific transparency, yet inevitably leaves room for difficult ecological questions.
The Saving Wildcats project, which has successfully released 46 individuals into the wild since 2023, relies on rigorous post-release monitoring using GPS-radio collars, camera traps, and scat analysis. The data overwhelmingly confirms that the wildcat’s diet specialises heavily on rodents, particularly field voles, complemented by a preference for rabbits where populations are dense. Tracking data illustrates a clear selection for rough grassland, scrub, and clear-fell habitats, precisely the environments where these prey species thrive.
However, the wildcat is an opportunistic generalist. The team acknowledged recording two verifiable instances of released females feeding on capercaillie carcasses—a sub-adult male and an adult male—alongside a third site suggestive of a possible kill. Crucially, because the carcasses were too degraded for post-mortem analysis and no direct fatal attack was witnessed, the project maintains that it is scientifically impossible to distinguish between active predation and opportunistic scavenging. The project stressed these were isolated incidents recorded in 2024, with no similar activity observed since.
While the official response is scientifically cautious, a broader ecological interpretation suggests the interaction is more loaded than mere scavenging. A critical field observation notes the absence of “whitewash mute” (the typical uric acid faeces of raptors) at the sites, making avian predation statistically unlikely. For three carcasses to accumulate naturally in proximity without predator intervention defies probability. Realistically, the discovery of multiple capercaillie remains in areas frequented by wildcats suggests the cats were responsible for the mortalities.
The project’s assertion that a 5kg adult capercaillie poses a “serious threat” to a 3.4–4.3kg female wildcat arguably underplays the lethal capability of a felid predator. History and biology show us that a hungry carnivore—be it a wildcat or a pine marten—is supremely capable of subduing larger ground-nesting birds, particularly a species like the capercaillie, which is vulnerable during its iconic lekking displays.
This leads us to a critical oversight: the availability of lagomorphs. The primary prey buffer for the wildcat should be rabbits, yet Scotland’s rabbit populations have been decimated by Rabbit Viral Haemorrhagic Disease (RHDV1 and RHDV2), with complete wipeouts recorded in many regions. If wildcats are released into core capercaillie territory where rabbit densities have collapsed, the predator has no choice but to switch prey. A wildcat will not starve while surrounded by capercaillie; it will adapt. This raises a salient question: if wildcats and capercaillie prefer different habitats, as suggested, why have the releases been concentrated in the Cairngorms, the very last stronghold of the capercaillie, rather than other suitable regions of Scotland devoid of this vulnerable bird?
The absence of a supplementary feeding strategy—akin to the rabbit enclosures provided for the Iberian lynx in Spain—appears to be a missing tactical layer. If conservationists are unwilling to sustain rabbit populations artificially, yet release predators into a prey-vacuum, a predictable conflict with other threatened species is engineered.
This delicate situation serves as a stark portent for the wider rewilding movement, particularly the ongoing discourse surrounding the reintroduction of the Eurasian lynx. Advocates frequently assure the public that lynx would not heavily predate capercaillie. Yet, as evidenced by Norwegian studies where lynx killed 25 capercaillie over a four-year period, a released predator will always exploit abundant prey. Proving causation is notoriously difficult; if we cannot conclusively witness a 4kg wildcat killing a capercaillie without a struggle, how will we police the interaction between a 20kg lynx and a ground-bird?
Furthermore, the disparity in conservation strategy is striking. While substantial resources have rightly been channelled into breeding and releasing wildcats, parallel requests by private estates to rear and release capercaillie to reinforce dwindling populations have historically been denied. If we accept the methodology of releasing animals into the wild to prevent near-term extinction, the logic must be applied uniformly. We cannot release predators into a fragile ecosystem without simultaneously flooding that system with the prey species they threaten.
The Saving Wildcats project is an extraordinary, evidence-led endeavour vital to restoring Scotland’s biodiversity. However, the return of a predator to a landscape altered by disease and habitat fragmentation requires unflinching honesty. We must acknowledge that a wildcat, driven by hunger in the absence of rabbits, will not spare a capercaillie because it is also endangered. Nature does not triage. The burden falls upon conservationists to pre-empt these conflicts, rather than merely recording the casualties posthumously.
Calum Campbell is a commentator on rural and environmental issues in Scotland.