More than one way to skin a rat

RATS have been very much in the news recently for a number of reasons but mainly because of the programmes of eradication on islands.

The one island that hit the headlines a few years ago was the Isle of Canna, west of Mallaig, and the latest one is the Isle of Rum. However, before we get onto the island problems over rats and seabirds there has been a mystery with a rat in our garden and I hope readers may be able to solve it.

One day last week I shot a large rat in the garden and left it there until I went outside. Next time I glanced out of the window there was a hooded crow attacking something on the ground. I thought it was a duckling but in fact it was the shot rat that the bird had moved out of a shrubbery and was eating it.

Foolishly, instead of getting the camera out, which would have made an unusual photograph, I frightened the hooded crow off.

Late that morning I looked at the rat and the hooded crow had torn open its throat and nothing else. I just left the rat there but needless to say the hooded crow did not come back.

However, I left the rat overnight and next morning went to see what had happened and this is where the mystery occurred. The rat had been very neatly skinned and the whole carcase just left but the skin had gone.

I can only think that a badger had come along, as they do every night, to peanut bait, and had skinned the rat, as they do with hedgehogs, but was disturbed so the carcase of meat left.

However, the skin had disappeared so what had taken that? Any suggestion or explanation from readers would be greatly appreciated.

As for the islands, most of the problems lie with the predation on seabirds by brown rats – but there is the one exception and that is the rats on the Shiant Isles in the Western Isles. These are not the brown rats but the very rare, in the UK, black rats.

“Very rare” is an often overused phrase among naturalists but in this case it is a truism as it may well be that the Shiant Isles holds the only colony of black rats left in the UK. However, despite this rarity the cull on the black rats is continuing and we await the results with interest. What will be just as interesting are the counts of seabirds on this archipelago before and after the cull.

The latest information about rats and islands comes from the Isle of Rum and is in the report commissioned by Scottish Natural Heritage. It looks mainly at the problem of rats in relation to the nationally important colony of Manx shearwaters.

Other islands have had problems with these iconic birds but in the case of Rum they are rather different. The reason is that their nesting burrows are on the upper slopes of the hills on the island.

I was particularly interested in the report as at one time, when I worked for SNH, I occasionally had responsibilities on the island. I well recall the large numbers of rats in the village at Kinloch but cannot remember seeing any on other parts of the island.

One of the problems with the rats is that it is such a large island at 10,463 hectares compared to Canna’s 1,130 hectares.

One basic statistic yields the importance of the Rum colonies of these mysterious seabirds as the island supports around 100,000 pairs of Manx shearwaters which is almost a third of the world population. The UK population is around 300,000 which again stresses the importance of the Rum colonies.

As for the report on Rum I have a hard copy in front of me and it makes fascinating reading, especially the fieldwork and the conclusions.

One of the problems is that there seems to be insufficient evidence that the rats are indeed having an effect on the numbers of shearwaters. One suggestion is that, while the birds could be a source of food in the breeding season, outside that time of year there is nothing to support rats on the tops of the hills. So more work is needed before a final decision over the cull is made.

This is just as well as the estimate of an eradication programme on the island is £4.6 million – yes, that is right – £4.6 million. Food for thought?

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