The Lynx Binding Life And Death
In the absence of apex predators in Scotland, key ecological interactions, such as carcass scavenging, are either absent or significantly suppressed. A steady supply of dead deer, partially eaten by lynx, would increase the year-round availability of carrion – a resource that, ironically, supports so much life.
The ecological benefits of returning lynx to Scotland include their impact on deer, with the potential this presents for woodland expansion. Separately, discussions have centred around a likely boost for ground-nesting birds, due to the lynx’s expected suppression of foxes. Less recognised, and largely overlooked until now, are the various benefits that might arise out of the lynx’s predatory leftovers, with many species standing to gain – either directly or indirectly – from a more regular supply of deer carcasses in the landscape.
Large carcasses are unnaturally scarce in Scotland
Presently, the availability of large carcasses in Scotland is relatively clustered in space and time. Up to 12,000 deer are killed in vehicle collisions each year (peaking in early summer), but this mortality is massed along our busier roads. Meanwhile, in the absence of an apex predator, wider mortality is skewed towards the end of winter, when hunger and exposure drive a seasonal spike in deer deaths.
Dead red deer stag on side of A9 road, Drumochter Pass, Scotland.
Hunting pressure from humans is also unevenly distributed, and although male deer can now be shot throughout the year in Scotland, many deer managers are expected to continue to avoid the traditional closed seasons. More significantly, little except the gralloch – the animal’s entrails – is ever left behind, since abandoning a complete carcass is viewed as both wasteful and disrespectful. Dead domestic livestock must also be removed from the landscape by law, with the result that large carcasses are unnaturally scarce in Scotland, especially in late summer, with their availability limited at a time when invertebrates are active and in need of food.
A steady supply of dead deer, partially eaten by lynx, would increase the year-round availability of carrion – a resource that, ironically, supports so much life. Indeed, carcasses form important oases of biodiversity, with new life endlessly resurrected from the opportunities provided by death. Carcasses support a unique collection of organisms: animals, bacteria and fungi known collectively as ‘the necrobiome’.
The carcass then gradually collapses into the ground as it is consumed from below.
Beetles are especially attracted to dead bodies, either consuming the flesh directly, or like the evocatively titled devil’s coach horse – a type of rove beetle – using them as hunting grounds to relentlessly pursue other scavengers. One group, the carrion beetles, base their entire lifecycle around carcasses, giving them their other common names: the sexton beetles, or the burying beetles.
Male carrion beetles are experts at rapidly tracking down death, racing to beat the onset of microbial decay. Large carcasses can attract a wide range of these efficient undertakers, but at present, some species, such as Thanatophilus dispar, are only known from a couple of sites in Scotland, with a shortage of carcasses potentially limiting their distribution. Having found an appropriate carcass, the male beetles burrow beneath it, attracting females to their tunnels using pheromones. The females then lay their eggs within these ghoulish crypts, providing their developing larvae with a convenient larder. The carcass then gradually collapses into the ground as it is consumed from below.
Ground nesting birds previously targeted by foxes experienced a useful reprieve.
Of course, reintroduced lynx would hunt all year, killing on average a deer each week, and the resulting carcasses would not be clustered towards the end of winter or concentrated along roads, where scavengers risk becoming roadkill themselves. Instead, lynx kills would be scattered throughout their preferred woodland habitat, supporting not only insects like carrion beetles, but also wildcats, eagles and other opportunistic scavengers.
In fact, lynx often utilise surprisingly little from a carcass. In Norway, male lynx may only eat 16% of the edible parts of their prey, leaving a veritable buffet for other diners. This glut of freely available food can then ease pressure on other prey species, as smaller predators are able to make up more of their diet from scavenging. This is what happened after lynx recolonised parts of Sweden, after which the proportion of venison in the diet of local foxes soared. Furthermore, this dietary shift did not boost overall fox numbers – since the lynx were also regularly killing foxes – but because the surviving foxes were hunting less and scavenging more, it meant that ground nesting birds previously targeted by foxes experienced a useful reprieve.
Specialist scavengers may be the obvious beneficiaries of large carcasses, but dead animals are also exploited by a variety of more surprising species. Butterflies, bees, ants, wood mice and crested tits are all happy to avail themselves of free nutrients, especially in the lean winter months. Nor are the beneficiaries limited to the animal kingdom. Recent research suggests that the nutrient pulse from the decomposition of a large carcass can contribute to nearby plant growth. One study recorded how welted thistles grew five times larger around red deer carcasses, supporting an increased abundance of insects, while another study found that disturbance around carcasses temporarily interrupted the herbaceous layer in woodland systems, promoting the survival of tree seedlings.
Complexity is giving way to simplicity. Diversity is declining to dull uniformity.
Ultimately, increasing the availability and distribution of large carcasses promises to restore a variety of natural processes, boosting biodiversity and serving to counteract another type of decay – the phenomenon of ecosystem decay, whereby life’s rich tapestry becomes gradually winnowed away. Worldwide, the march towards biological austerity is being driven by human activity, by habitat fragmentation and the subsequent breakdown of many natural processes. Complexity is giving way to simplicity. Diversity is declining to dull uniformity.
Rotting bodies may elicit an instinctive revulsion, but in healthy systems, scavenging birds, mammals and invertebrates dominate decomposition and limit the influence of microbial decay. Restoring our familiarity with large carcasses attended by abundant scavengers could also serve to catalyse a subtler change in ourselves, reminding us of the visceral realities of life’s ultimate circularity, while offering us a chance to appreciate the efficiency with which nature recycles everything. Death has become sanitised and strangely unfamiliar in modern life, an event rather than a process, but perhaps renewing our acquaintance with its fruitfulness should be considered an important part of rewilding ourselves.
We don’t yet understand all the ways that large carcasses contribute to the complex cycling of nutrients, the maintenance of biodiversity, or the movement of carbon between the soil and the atmosphere, but everything we’re learning points to these vital processes being underpinned by a marvellous complexity. Of course, reintroducing lynx to Scotland won’t magically fix all our ecological problems, but any boost in carcass availability would certainly help. And while not every organism within the necrobiome may be necessary in the most reductive sense, every species offers us fresh opportunities to wonder at nature’s beauty. In the end, rewilding is about hope, and what could be more hopeful than a reminder that there’s life after death?
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This feature is published on behalf of Lynx to Scotland, a partnership between Trees for Life, Lifescape and SCOTLAND: The Big Picture.
