Sunday 5 July 2009

Sound of crickets spreads in Britain

Crickets, the chirping insects more typically associated with the Mediterranean, are spreading across the British countryside.








Entomologists are reporting that crickets are spreading across the country thanks to the warming climate, making their distinctive mating call a common sound.



Rare species that were once restricted to just a few southern coastal regions in England have now become widespread as food and breeding conditions have improved.





Crickets such as the Long-Winged Cone-Head, which was one of the rarest in Britain 20 years ago found only in a handful of sites on the far south east coast, have extended as far north as Leicestershire and west into Cornwall.



The Roesel's Bush Cricket, previously confined to a few grasslands in estuaries on the south east of England have now become common around the Thames, The Solent and the Humber.
Other species that had never been recorded in Britain before, such as the Southern Oak Bush Cricket, have appeared for the first time.



Dr Peter Sutton, national recording scheme organiser for orthoptera and allied species for the Biological Records Centre, said: "Many cricket and grasshopper species are enjoying a meteoric rise here in the UK.



"Since the 1980s some of these species have spread rapidly as the climate has become more favourable.



"As the temperature in the UK has moved up, different habitat types have become accessible to these species as it has become warm enough for the eggs to mature. This year has been a perfect year.



"While last year was fairly catastrophic because of the wet weather and we had very low sighting reports, many crickets can account for bad summers by having eggs that take two to three years to hatch so they can sit out the bad years.



"We are expecting to see many of these species will have expanded their ranges even further this year."



Crickets, which are part of a group of insects known as orthoptera, are more commonly found in warmer climates where they can find the higher temperatures they need for their eggs to mature.



Male crickets are famous for their distinctive mating call, known as chirping, which they produce by their wings together. Ridges along a thick rib on the left forewing produce the noise when it is scraped across the edge of the right forewing.



Each species produces a unique call from a series of low clicks to a high pitch trill.



Bjorn Beckmann, from the Centre for Ecology and Hydrology, has found that 11 species of orthoptera have expanded their range since 1990.



The most successful is the Long-Winged Cone-Head, Conocephalus discolour, which first appeared on mainland Britain in 1945 but was considered a rare species living just five miles from the south east coast until it began spreading at the end of the 1980s.



It has now managed to spread more than 130 miles to the north and is found commonly on road verges.



The Short-Winged Cone-Head, Conocephalus dorsalis, which is less mobile than its long-winged relative, was also only found along the south coast 30 years ago, has also extended its range onto road verges, railway sidings and scrublands as far north as Cumbria.



House crickets, which in the past could only survive indoors protected from the elements, are also on the increase with large outdoor colonies appearing in landfill sites where they obtain heat from the decomposing waste.



One notable colony was found on a landfill site near Cambridge.



It is thought that decreasing summer rainfall and rising temperatures are mainly responsible for the spread of the insects.



Brian Eversham, conservation director for the Wildlife Trust in Cambridgeshire, Bedfordshire and Northamptonshire, said: "Crickets have spread very dramatically – far more than any other insect in Britain.



"The Long-Winged Cone-Head is now one of the most common crickets in Cambridgeshire. I was on a reserve in Bedfordshire this week and we could hear crickets singing wherever we went.



"The countryside is probably a lot noisier now than it was 10 years ago as a result."



The Long-Winged Cone-Head, one of the rarest in Britain 20 years ago found only in a handful of sites on the far south east coast, has extended as far north as Leicestershire and west into Cornwall.


By Richard Gray, Science Correspondent http://www.telegraph.co.uk/earth/wildlife/5740791/Sound-of-crickets-spreads-in-Britain.html

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