Brambles soar over the acre’s hedges like the grapnel-lines of a medieval siege. Most of the berries they offer are still meanly tight, where ripe at all. But the arching new growth of the briars stretches leafy tips down to the soil, there to take root for starting a new leap next spring.
It seems the ambition of Rubus fruticosus, the common blackberry, to take over the whole island. Hedgerows may have come late to Ireland, but brambles fended well for themselves in the wake of forest clearance.
Evolving dozens of microspecies with differing leaves and fruiting styles, they survived the attentions of foraging goats and the kindling needs of crowded town lands. Today, away from big dairy farms (brambles scratch tender udders) and barbered road verges, the differing briars flourish together in neglected hedges and on waste sites everywhere.
Apart from their own driving progress, they propagate through the appetites of highly mobile wildlife. Purple splashes on laundry pegged out on the line speak for thrushes and blackbirds. Late-autumn droppings of foxes and pine martens are often solid with pips. And now blackberry-feeding badgers are allotted a special role in furthering Ireland’s biodiversity.
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In 2019 they made the cover of the science journal Mammal Communications with the question: Are badgers, Meles meles, effective dispersal agents for bramble, Rubus fruticosus in Ireland? The supporting paper was from a team at UCC’s school of environmental sciences, headed by mammalogist Dr Paddy Sleeman.
Dr Sleeman is a long-haul researcher into badger behaviour and bovine TB. On his frequent visits with students to badger setts and their latrines in woods and parkland around Fota he noted the high density of brambles around the setts.
Badgers, like most humans, are fussy about where they defecate. They dig special holes for the purpose — latrines perhaps a foot across — at the frontiers of their territory. The UCC team extracted abundant blackberry seeds from fresh latrine droppings in October. They examined them with an electron microscope and compared their capacity to germinate after the winter with that of seeds from fallen berries.
The team found that passage through the gut actually stimulated the seeds’ capacity for growth. This suggests that badgers are thus increasing and maintaining their source of blackberries for food and improving their environment by helping brambles to grow. In a similar example, it’s theorised African elephants break tree trunks to promote the long-term coppicing of juicier food.
Dr Sleeman had also noticed another frequent growth around badger setts, that of the stinkhorn mushroom Phallus impudicus. This is normally a wood decomposer, fed by decaying tree stumps. It puts up a stoutly erect fruiting body like something drawn on a boys’ lavatory wall. The conical cap is coated with a sticky, olive-coloured gel that gives off a sweet stench, like rotting carrion.
The cap is soon covered with shiny green flies, feeding greedily on the gel, which contains millions of spores. When they fly away and defecate somewhere else, they are seeding new opportunities for the stinkhorn.
In a forensic touch, the flies include the dominant species of blowfly normally attracted to, and reared on, the carcasses of dead badgers. In the course of a year, his team found 443 stinkhorns, nearly all within 50 metres of nine setts in the research territory.
Along with digging vast underground labyrinths (the biggest in one Irish survey had 44 entrances), the badgers’ impact on brambles and stinkhorns makes them significant ecosystem engineers.
Taking part in a major European research colloquium next week, Dr Sleeman will urge strong fences around badger setts, most of which are in hedgerows and field banks.
Clumps of nettles at setts also come into that frame. They are food plants for butterfly caterpillars (peacock and lesser tortoiseshell). Their tough and ramifying roots are also part of the rhizosphere, the underground layer of soil enriched by chemicals that plant roots release. Coupled with spoil from the badgers’ excavations and benefits from fungal underground networks, research into the rhizosphere could lead to better yields of food plants in a hungry world.
Meanwhile, there’s mixed research into the origins of Ireland’s Eurasian badgers (some 84,000 in the Republic, at Dr Sleeman’s last estimate).
A genetic study published in 2009 and led by TCD’s Prof Dan Bradley, linked them to postglacial human settlers from northern Spain. But in 2020 a study of Irish badger genetics led from Northern Ireland’s Agri-Food and Biosciences Institute and published by the Royal Society demonstrated “that badgers in Ireland’s north-eastern and south-eastern counties are genetically similar to contemporary British populations”.
Simulation analyses, said the institute’s Dr Adrian Allen, suggest “this admixed population” had origins in introductions by people 600-700 years ago.