Islands are very special places and whilst their wildlife may not be as diverse as that of the nearest mainland, sometimes it has evolved to have some unique characteristics. Isolation also makes island communities very vulnerable to the arrival or introduction of non-native species, including those which may be native to the mainland. So not only are we fighting to control and eradicate invasive plants like Gunnera and Rhododendron ponticum we also have problems with hedgehogs and feral ferrets. Everyone adores hedgehogs, but since they were introduced here in the 1990s they have spread through the islands and are having a seriously detrimental effect on our populations of breeding waders. It is perhaps not commonly appreciated that hedgehogs are partial to eggs.
The climate in Britain has warmed over the last four decades, and in response to changing environmental conditions, some species have been able to extend their distributions northwards. The extent of distribution changes has varied greatly among species, with some showing rapid expansion and others showing none at all. Many of these changes do not appear to have an adverse effect on the local flora and fauna but there will be cases where the effect can have a significant effect on the local wildlife.
Here, in the Outer Hebrides, perhaps the most noticeable effects have been the appearance of some new species of butterflies, orange-tip, speckled wood and peacock, in recent years.
Deciding whether the arrival of new species of plants is natural or the result of a deliberate or accidental introduction is more difficult. Cowslips, Primula veris, are not native to the islands, but they have been recorded in South Uist on a few occasions in recent years. I grow primroses, Primula vulgaris, in the cottage garden, but they have not spread beyond the garden. It is a native species so I would not be too concerned if it jumped over the garden wall. I have never grown cowslips, so I was rather surprised to find them growing on a grassy area near the fruit cage and in the grass along the drive. These areas were not sown and are just areas of grass which we keep mown. To be honest they are more of a mix of wild flowers (including dandelions, docks and other assorted flora which is usually classified as weeds) and coarse native grasses than a manicured green sward.
So the origins of the new arrivals are obscure – natural colonists or an accidental introduction? Whatever their pedigree they are welcome, but I will be moving them into the cottage garden just in case they have hidden invasive tendencies.