Nigel Jee’s Country Column – non-native species that are at home in Guernsey

September 23rd, 2010 by Nigel Jee

This column has recently featured sandhill snails, Japanese knotweed, rabbits and various pests of garden plants and crops. What they all have in common is that they are not native, but were brought here, either deliberately or accidentally, by humans. This thought made me wonder how many animals and plants, which we now take for granted, are invaders, and the number is astonishing.

Some, like Japanese knotweed, have proved to be disasters, but others have settled down and become a welcome part of the scenery. It would be difficult to imagine the island without ‘stinking onions’ brightening up the hedges in spring, or the town without St Peter Port daisies decorating the walls.

Other newcomers have arrived by purely natural means, as their range spreads northwards in response to global warming. Until the 1980s a little egret was a rare sight on our coast, and the nearest breeding colony was in the Camargue in the south of France. Then the small, white herons began breeding in Brittany and we saw more and more standing in the rock-pools around Guernsey. Now they are with us all the year round, and have just begun to breed in the Bailiwick.

Argiope, the ‘wasp spider’, is another invader from the south. The conspicuous yellow spider with black stripes was first seen in Guernsey in 1995, and at first it caused some alarm. It is now breeding regularly, and in spite of its warning coloration it is no more liable to bite than a common garden spider.

A wasp spider, Argiope bruennichi, which has arrived in Guernsey (click image to expand - ©RLLord)

Not all the invaders come from the south. Two birds have bucked the trend and are spreading southwards from the north. Gannets, which used to breed only in the far north of Britain, established breeding colonies on Ortac and Les Etacs off Alderney during the German Occupation, and have since started to breed in Brittany. Fulmars used to breed in the British Isles only in the remote island group of St Kilda, far out to the west of the Hebrides. During the 20th century they began to move south, reaching the Channel Islands in the 1970s. Today they breed regularly on inaccessible cliffs in all the islands, for instance between Les Tielles and Mont Herault in Guernsey and near Putrainez in Herm.

In some cases imported species have proved to be better adapted to our changing climate than the native ones. Among trees the native ‘English’ oak is struggling, and there are many stag-headed specimens which have been unable to find enough water to maintain their full size. The Turkey oak, introduced from eastern Europe in the 18th century, grows faster and seems much happier. The evergreen holm oak, from southern Europe, is even happier, although it is doubtful whether planting it is wise, as nothing can grow beneath it.

Gardeners are the main agents in introducing new plants. Most of their introductions can only survive with careful cultivation and protection, but as the winters become milder, more and more are escaping into the wild. The giant Echium or ‘rocket plant’ from Tenerife has been growing in Guernsey gardens since the 1920s, but within the last decade it has begun to appear beyond the garden fence, and it will soon be a wild plant. It deserves encouragement, as bees love the flowers.

The spectacular Madeiran geranium is also beginning to appear in the wild. In the spring it is covered in magenta blooms, and the older leaves have to bend down and act as props to support the weight. Much less welcome are Japanese knotweed and Hottentot fig, both of which are spreading on the cliffs, and smothering the native vegetation.

Japanese knotweed smothering vegetation on the cliff path at Moulin Huet in July 2008 (click image to expand - ©RLLord)

Hottentot fig, Carpobroteus edulis, at Pleinmont in September 2008 (click image to expand - ©RLLord)

Nigel Jee’s Country Column was published originally in The Guernsey Press on 23 September 2010

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