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The colourful face of climate change

Posted: Wednesday 18th September 2013 by BrianEversham

Wasp spider, argiope bruennichi, by Brian EvershamWasp spider, argiope bruennichi, by Brian Eversham

From wasp spiders to emerald damselfly, the visual indication of nature adapting to warmer climes is all around us, as the distribution of southerly species increases

 

Anyone with doubts about climate change should take a stroll round Cambourne. The first adult wasp spiders of the year are active now. This continental species first arrived in Britain in the 1930s, presumably with young spiderlings ‘ballooning’ (casting a strand of silk into the air, and being carried high up on the breeze) across the Channel. Until the late 1980s it was confined to the south coast, from Dorset to Kent. A run of hot summers set them on a northward expansion, and they arrived here in the mid-2000s, and are now well established in the fine dry grasslands, feeding mainly on grasshoppers. Apart from their stunning black-white-yellow stripes, they are also unique in Britain in putting white warning flashes across their webs, supposedly to help birds avoid flying through them.  The females will soon spin their parchment-like egg cocoons about 3cm across, and next spring, a new generation of rather un-wasplike baby wasp spiders will emerge.

The meadows and verges at Cambourne are abuzz with Roesel’s bush-crickets, metrioptera roeselii, left, another colonist. These distinctive insects, about 2cm long with even longer sensory antennae, were found in coastal grasslands and along the Thames estuary until the 1990s. The song of the coneheads is gentler, like wind rustling reeds: the long-winged conehead was another south coast speciality till the 1990s, and is now widespread as far north as Lincolnshire and Lancashire. The short-winged conehead has shown a remarkable change in behaviour rather than distribution: till recently it was a scarce insect confined to fens and wet meadows; now it’s common in rough grasslands and road verges throughout our area.

You don’t even need to leave the garden of the Manor House to see new and brilliant wildlife.  The pond is brimming with bizarre flies, beetles, pondsnails and damselflies.  So far, we have only the gorgeously blue-eyed common emerald damselfly, but a very recent arrival, the longer, slenderer willow emerald, is abundant not far over the Suffolk border, so it could be in Cambridgeshire any day now. At this time of year, take a look at the lavender and you’ll see insects which were nowhere in central England a decade ago.

The shining rainbow-coloured American leaf-beetle is a cheat - brought here by people and transported by the horticultural trade.  But the equally striking red-and-black bug, corizus hyoscyami, is a long-standing native which has spread, and found new habitats.  It was previously confined to coastal single and sand beaches in the south and south-west.  Now, it’s turning up increasingly in gardens and in meadows.  Another bug, till recently typical of dry heathland and grassland, rhopalus subrufus, below, is also living gregariously on garden lavender. And in my own garden, the commonest harvestman is now the orange, black-legged opilio canestrinii, a species which has spread across Europe from the Mediterranean in the last 30 years, and seems to be out-competing many native species.

The changes in distribution and behaviour illustrate how unpredictable are species’ responses to climate change. Not only do southern species spread northward, but some species begin to use habitats which only a few years ago seemed completely unsuitable. Nature will continue to surprise us.  But, if all our native and colonising wildlife is to survive, we need to give them the landscape and the nature reserves where they can thrive.  That’s the job of the Wildlife Trust and Living Landscapes.

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