THEY may seem like unorthodox methods to save one of Britain's fragile environments. But four tubs of Cadbury Bourneville dark chocolate and a stack of white dinner candles were the unlikely ingredients assembled yesterday to save St Kilda from ecological disaster.
In the cramped kitchen of a small bothy unoccupied on the remote island for decades, Abbie Patterson prepared his unique vermin-control methods.
He is tasked with exterminating rats which may have come ashore from the stricken fishing boat which
was foundered on the coastline in a force-nine storm last week.
Experts fear the rodents on board the Spinning Dale, currently trapped against rocks, will decimate the seabird colonies of St Kilda by eating birds' eggs, which are
laid in ground nests because of the absence of trees. The seabird population includes the world's biggest colony of northern gannets, as well as large colonies of puffins and other birds.
For the best part of the afternoon, Mr Patterson slaved over a hot pot, melting his wax-and-chocolate mix down before pouring it into a baking tray.
"It's an unusual way to do it, I know," the 57-year-old says. "But rats love chocolate."
Mike Russell, the environment minister, and St Kilda's owner, the National Trust for Scotland (NTS), have voiced concern that the vessel's hold may have contained vermin. At present, they remain only fears, but given St Kilda's fragility, the pre-emptive strike by Mr Patterson – the national species recovery officer for the NTS – is a necessity.
"There's been no sign or evidence of any rats so far, but they are very intelligent animals and naturally suspicious," he told The Scotsman on St Kilda yesterday. "If there are any in the boat, they know they don't have to come out right away. They will wait, and they can get ashore.
"They are tremendously strong swimmers. It amazes me to think that for all the progress mankind has made with inventions and technology, rats are still with us. And it frightens me a little, too."
The prospect of the rats' arrival on St Kilda, Mr Patterson, from Edinburgh, added, was potentially catastrophic: "All it would take is one pregnant female to get ashore and it would start a chain of events that would be difficult to stop. If rats got into the burrows, it would be devastating."
Having mixed his bait yesterday, he will spend today and the next two days scattering traps across the shoreline of Village Bay, where the trawler currently rests.
Spaced 50 metres apart, many near to puffin burrows , the traps will not contain any poison, or prove lethal to any rat who might happen upon it. St Kilda's field mice are also considered a valuable species – along with the Soay sheep, they are the only mammals – and must be protected.
When he leaves on Friday, having fully briefed the NTS and the staff of Qinetiq who work at the Ministry of Defence radar installation on St Kilda, the few remaining inhabitants will monitor the chocolate-and-candlewax biscuits for tell-tale signs.
If after six weeks vermin teeth marks are nowhere to be found, Mr Patterson will pronounce himself confident no rats have breached the World Heritage Site and UNESCO reserve.
But, should the worst-case scenario come to pass, the archipelago is in assured hands. Over the course of his decade-long career with the NTS, Mr Patterson has learned how best to contend with a variety of species as diverse as moths and red squirrels, but rats have featured most prominently.
He was the architect of an initiative designed to rid Canna of its vermin scourge. That Hebridean isle fell foul to the brown rat in the late-19th century, when the first of the animals arrived on incoming vessels as unwelcome passengers. A century later, their population numbered 10,000 and had laid siege to Canna's precious European shags, razorbills, Manx shearwaters and guillemots.
Mr Patterson's solution, implemented two years ago, employed the same bait he was yesterday laying across St Kilda's shores. The logistics of the Canna programme were demanding, with some staff required to abseil in order to place traps in the nooks of sea cliffs. Ultimately, however, it reaped success and, come spring, Mr Patterson predicts, Canna will be able to declare itself rat-free once more.
The few regular visitors to St Kilda are naturally upset at the turn of events since last Thursday, yet exhibit a faith that this hardy environment will prevail.
St Kilda was designated a World Heritage Site for its massive cliffs and profusion of seabirds, such as the 60,000 pairs of northern gannets.
The islands are the most important seabird station in the north-east Atlantic and also have large colonies of puffin, fulmar and Leach's storm petrel.
There are also concerns about the impact of the trawler's estimated 8,000 litres of diesel and oil, if the fuel was to leak.
Angus Cameron, owner and skipper of Kilda Cruises, who takes naturalists and photographers to view some of the most remarkable vantages, offered a pragmatic view yesterday. "It's sad to see all these traps having to be laid. It's not natural for St Kilda. But I think this land has been here for a long time for a reason, it'll survive," he said.
Susan Bain, the trust's property manager for St Kilda, said rat traps set on Friday were found to be empty.
"We know rats don't always co- operate and go into traps, so it is important that we have sent out specialists who will establish if there are results or not.
"There is only a slight risk, but we can't afford to take any risk with a world heritage site."
For all the beauty she has bequeathed on St Kilda over the last four millennia, Mother Nature is finally calling in a favour. The fact it involves dark chocolate and candle wax ought not to offend her.
POLLUTION FEARS
AGAINST the awesome landscape of Village Bay, the former main community on St Kilda's largest island, Hirta, it is easy to underestimate the scale of the wrecked trawler.
Weighing 117 tonnes, and 82 feet long, the vessel appears almost insignificant beneath the cliffs, some of which reach heights of 1,400 feet.
Its crew, 14 Spanish fishermen, were airlifted to safety in a dramatic rescue as storms battered the UK on Friday.
One need only survey the scene surrounding the trawler to urge caution. There are but a few feet of water between the upturned hull of the ship and the shoreline, and the air is pungent with diesel fumes as the Spinning Dale's fuel trickles ominously into the bay.
So far, the tides have been forgiving, but until it is removed, the vessel will continue to break up, with the risk of pollution. The Marine Accident Investigation Branch is launching an investigation into the grounding.
