Beautiful deer are nibbling native woodlands into non-existence
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Deer are beautiful animals. We see them in hills and forests, jumping gently through heather and scrub, their rich brown fur catching autumn light as though they were always part of the Irish landscape. Their delicate physique, light gait, and big eyes trigger empathy and compassion in us. There is the ‘ factor’ too of course — most of us have the Disney story embedded in our perspective.
There is a long history of deer in Ireland. Reindeer were once common right across Ireland. Giant Irish Deer, a now extinct species, roamed across the open plains during interglacial periods, boasting enormous antlers spanning 3 metres across and weighing in at 30 kilos. Giant Irish Deer probably weighed about a tonne. The bodies of many Giant Deer have been well preserved in midlands peat bogs, whose skeletons and giant antlers are now displayed in museums far and wide. For this reason, this species of ‘giant deer’ has become known as the ‘Giant Irish Deer’, even though these giants were present throughout Europe at the time.
Today we have several types of deer in Ireland, most of them introduced for hunting. The red deer that some consider native in Ireland today were probably transported here in boats from the continent by the first farmers, about 6,000 years ago. These were an animal that roamed free in herds, and then hunted for their fur, their meat, and their antlers. The 700-plus red deer in the Killarney National Park are thought to be genetically ‘pure’ descendants of these red deer.
Fallow deer were brought here by the Normans in the 13th century and through the middle ages were kept in ‘deer parks’ all over Ireland. Fallow deer are now the most populous deer here.
Sika deer are a species native to Japan, first brought to Ireland by Viscount Lord Powerscourt in County Wicklow in 1860. As the Powerscourt Sika deer herd grew, some were sent to Killarney and quickly established themselves there too. From just a few Sika deer that were first introduced on one large estate, within a few decades Sika deer became established in many parts of the country. There are now thousands of them running wild across the mountains and forests of Ireland, nibbling away at heaths and woodlands, stripping away native vegetation and tree bark, causing extensive ecological and economic destruction.
The recent history of Irish woodlands is closely intertwined with deer. It’s hard to walk through a deciduous woodland without being bombarded with evidence of deer damage. They browse on all the little woodland herbs that would naturally grow on the ground. When a woodland is without its ground layer of plant life, this impacts the diversity and abundance of the insects that depend on these plants. Gone are the lower layers that support butterflies, bumblebees, hoverflies and all manner of invertebrate life. This in turn reduces the population of small mammals and the many birds that also feed on protein-rich invertebrates. The impacts ricochet up through the woodland food chain, right up to the top predators such as sparrowhawks, goshawks, and long-eared owls.
Walking through a woodland at this time of year is a wonderful experience, looking up at the light filtering through the overhead canopy, where limbs of enormous oak trees create a cathedral-like ambiance. Yet where deer are rampant, these mighty trees have no successors, as most of the young sapling trees are nibbled away to nothingness by the insatiable appetite of invasive deer, who eat almost any plant material that grows within their browse line. Absent is the tangle of growth that should characterise healthy native woodlands. This is causing the death of many remaining Oak woodlands. All across the west, from Donegal, Sligo, and Mayo down to Cork and Kerry, native woodlands are dying on their feet.
There are efforts are in place to address this. Many old native woodlands have two-meter-high ‘deer-proof fences’ in place, intended to keep browsing deer at bay. But wherever one finds a wonderful old woodland, fences aren’t adequately maintained and deer are still nibbling away at the woodland's precarious future. In some cases where deer fences have been breached, the deer are cornered into parts of the woodland and can’t escape, so the browsing damage appears even worse than if there was no fence there at all. Other invasive species, including rhododendron, cherry laurel, and feral goats are also taking their toll on the woodlands’ chances of regeneration.
In a balanced ecosystem, there would be wolves keeping a cap on the deer and goats. But we killed the last of our native wolves a few hundred years ago, and now deer have no natural predators. Better fencing — rigorously maintained — is urgently needed. Appropriately targeted deer culling is needed too, to limit the damage and give. The last remnants of these most precious ecosystems need a chance to maintain themselves.
It’s come to a point where we have to do far more to manage the delicate balance of our remaining native habitats. Less than 1% of Ireland's land area is covered in native woodland. In an era of biodiversity collapse and climate change, more, not fewer woodlands are needed. But browsing deer are preventing the ability of these crucial natural habitats to expand. Saplings spread by natural means, which might otherwise help woodlands to gain lost ground, are also eaten back by deer.
Autumn is the perfect season for wandering through native woodlands. We can experience immersion in the warm colour palette of vivid yellows, rich russets, and flamboyant flame reds. Fungi of every shape and size proliferate. But there is little time left for these habitats in Ireland and we are letting our remaining native woodlands die on their feet, crippled by deer and other invasive species.