Black rat ranks as rarest animal in Britain
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QUERIES from readers are always more than welcome, especially when they pose a question that needs a great deal of thought.
The query sounded straightforward: "What is the rarest animal in the Highlands?"
Easy, I thought, as it would have to be the wildcat as some pessimists believe there are only 200 true wildcats left in the Highlands, let alone the UK.
It would have been easier to have asked which is the commonest animal. There would be plenty of contenders such as red deer, rabbits and moles,
And what about the one animal we try to ignore, hoping it will go away – namely the brown rat?
As thoughts of the brown rat crossed my mind, the rarest animal was suddenly obvious as it must be the black rat, which most of us never hear anything about these days.
With my recent articles on favourite islands such as North Rona and St Kilda, the Shiants really should have come to mind. This archipelago lies 10 miles off the coast of Lewis in the Hebrides.
The reason I mention it is that two islands in this archipelago support the only resident colony of black rats anywhere in the UK, so it is the rarest.
It is not native, having been introduced to the UK many years ago, although the origin is obscure.
While North Rona and St Kilda may be, in that order, my favourite islands, there are others that I have a soft spot for such as the Monach Isles and Rum.
I recall how intrigued I was to see black rats on the Shiants when I went there in the early 1980s. One count estimated that black rat numbers at around 1,000 existing on two of the islands.
They are more vegetarian than brown rats so were not thought of as a threat to the huge numbers of seabirds on the Shiants. So they were left alone as they were presumably co-existing quite well with the breeding birds.
That is until recently, when a new survey put black rat numbers at 3,600 and more in the summer months, when food is plentiful.
Then came the evidence that at one time Manx shearwaters and storm petrels bred on the Shiants, two rare seabirds that are absent at present. Trapping also showed that black rats frequently ate birds as feathers were found in their digestive systems.
The presence of rats, albeit brown rats as opposed to black rats, on such islands as Canna and Handa, indicated sharp declines in the numbers of some breeding seabirds.
A very successful eradication programme was implemented on both these islands, with a subsequent rise the numbers of breeding seabirds.
So there has now been a change of heart over the black rats of the Shiants and an eradication programme will be implemented.
One problem is the cost, which has been estimated at £900,000, but a major grant has been secured from the European Commission for nearly £500,000, with a further £200,000 coming from Scottish Natural Heritage.
While the eradication may be expensive and time-consuming, so will the monitoring afterwards, which is often forgotten about.
Intriguing to me is that while these programmes are being and have been implemented, with impressive results, why are brown rats on Rum not being eradicated?
Rum has a huge breeding colony of Manx shearwaters that is of international importance and it is unusual in that it is centred on the hill tops on the island.
RECORD OF THE WEEK
Riddle of playful woodmice
I was looking at some small trees and although there were plenty of birds singing and calling, I could not actually see anything, moving or still.
Then a movement at the bottom of the nearest tree caught my eye, and after few moments of watching posed a mystery that I still have not solved.
The woodmice were very active, all five of them, and at first I just thought they were scavenging after seeds. Then they started running round and round the tree at its base which I thought was strange, but there again I am not in the habit of watching woodmice.
Next an extraordinary thing happened. They started leapfrogging over each other and suddenly turning sharply in tight circles.
Then, as if by an unseen signal, all five started running around the base of the tree again.
Again, as if by a signal, it was back to leapfrogging and turning in tight circles, with the whole process repeated. After a few minutes it was if the mice were bored as they all scampered off in one direction back to the hole they lived in.
These intense activities seemed to be simply play. But do woodmice play?
I can’t find any reference in my books to wood mice "playing", so perhaps a reader can enlighten me.
