We have just had a wee reminder how complex the natural world is, and how man's interventions down the centuries are still being felt today.

Take the pine marten and the capercaillie. Both have been declared protected species because of the impact of our forebears' activity, which drove them to the point of extinction, or indeed beyond it.

It is thought pine martens were once the second most common carnivore in Britain. But clearance of woodlands, trapping and persecution by gamekeepers and other land managers had a devastating effect.

By the turn of the 20th century, the once widespread distribution was reduced largely to north-west Scotland. In 1988, the species was given full legal protection and it has recovered significantly to the point it can now even be found as far south as the countryside just north of Glasgow.

Meanwhile, the capercaillie became extinct in Britain in the mid-18th century, largely due to the destruction of native woodlands. In 1837 some from Sweden were reintroduced into Perthshire and by 1970 there were thought to be around 20,000 in Scotland.

However since then the numbers have fallen dramatically to around 1,200 in 2010, with Strathspey in the Cairngorms National Park now accounting for 80%.

The former is now held by some to be the main threat to the latter's continued survival. Although pine martens are generalist predators, feeding on small rodents, beetles, carrion, eggs, fungi and berries they certainly don't turn up their noses at birds or their eggs. So they are not favourites of our sporting estates.

The pine marten (Martes martes) has become a very hot topic in the politics of rural Scotland. To be more precise, it is the latest front in continuing engagement between landowners and their gamekeepers, with conservationists.

We've had reports of a leaked plan from the Game & Wildlife Conservation Trust, a charity funded by landowners, farmers and sporting interests. Apparently it wants to launch a trial next year to trap and relocate 120 pine martens over six years from four Strathspey forests.

Meanwhile, this week the Scottish Gamekeepers Association was also advocating a relocation trial from a small core area of woodland, to see if it would lessen the pine marten's predation of capercaillie nests in Strathspey.

But that's not how conservationists see things, as Justin Prigmore, the park authority's Cairngorms nature officer and Capercaillie Framework Project Manager, explained: "There are some capercaillie in Moray and Nairnshire, and some up at Novar (Easter Ross).

"But there may only be one bird left on the Loch Lomond islands. It has been the same story across Highland Perthshire, where they are a few woods that may have a bird or two. There are some near Blair Atholl which is within the park boundaries. They are still breeding there.

"There are also a few birds at the Forest of Birse just outside the park in Aberdeenshire. But the main focus is Strathspey in the park. It is only place where we know the birds are at least stable or possibly increasing. But it is a bit early for champagne corks."

There are thought to be a variety of reasons for their decline since 1970: loss of suitable woodland habitat, partly due to over-grazing of blaeberry by sheep and deer; increased predation from crows and foxes, especially on breeding females; increased adult mortality through collisions with deer fences; climate change with increased adverse weather conditions during June when chicks are newly hatched; and possibly human disturbance, in part due to forestry operations and the recreational use of forest tracks.

So Justin Prigmore sees it as vitally important for the Strathspey stronghold to be secured and for it to grow so that capercaillie can start expanding into neighbouring areas.

"Connecting up to Deeside is a big goal for the national park in the future, through that corridor between Glen Feshie and Mar Lodge. After that we would be looking to see if we can expand into the Glenlivet area and further north into Moray to see if we can connect up these patches of forest."

But the Scottish Gamekeepers Association is cynical about this and any other approach that does not recognise the impact of the pine marten. "It must be questioned how much of a priority Capercaillie survival is, beyond sound-bites, if plans to conserve it make no mention of predator impact.

"The inability of conservationists to grasp the nettle on this is like a group of people trying to rescue their dinner while the house is on fire. Millions have been spent in removing deer fences and improving forest habitat, yet the decline of capercaillie continues.

"Our understanding, from speaking to workers on the ground, is that the numbers may be as low as 400.On 20 video monitored nests in Abernethy Forest, 65% of nests were found to be predated, 57% of those by pine marten. Given this science within the core area, and the rise in number of pine marten, it is surely common sense to proceed with a trial to translocate pine marten from a small core area to monitor the affects of, and better understand, such predation."

But the Cairngorms National Park Authority and Scottish Natural Heritage insist the figure is not nearly so low and that they are not ignoring pine martens. A considerable amount of research is in process also involving Forestry Commission Scotland.

There are also ongoing discussions with GWCT over their proposals for a trial relocation, but they would have to be "robust and scientifically sound."

SNH said: "We support this development phase but until it has been completed, and a fully worked up implementation project proposal reviewed, we cannot take a view on the merits of the work, nor on any proposals for removing pine martens."

Given the pine marten's protected status, nothing will happen until SNH gives the green light. And the agency is not going to rush to do that until it is absolutely certain it is the best course of action.

Many still working for SNH will well recall the greatest controversy to engulf the body, the SNH-led cull of unprotected hedgehogs on North Uist.

That began 11 years ago to protect ground nesting birds' eggs, only to be discredited when it was established the spiky ones could survive being moved to the mainland against the total certainty of SNH's scientific advice.

One might have thought this would make SNH more likely to accept a trial relocation. But there will be a lot of agonising before another controversial intervention.