Scientific survey finds big rise in key butterfly species at Horley site (From Redhill And Reigate Life)

Scientific survey finds big rise in key butterfly species at Horley site

10:03pm Monday 28th January 2013 in Local News

A key species of butterfly defied last year's downpours and jumped in number on a survey site near Horley.

The Wider Countryside Butterfly Survey (WCBS) revealed that despite 2012 being the second wettest year on record, grass-feeding butterflies flourished across the UK countryside.

And in particular, the Meadow Brown enjoyed its best year since the start of the scheme, with almost twice as many counted as in 2011.

In fact, the Meadow Brown was the most widespread butterfly for the third successive year of the scheme, being seen in 89% of site squares surveyed.

In the Horley area, the butterfly's improved showing was dramatic.

WCBS coordinator Dr Zoe Randle of Butterfly Conservation said: “Meadow Brown numbers went from one in 2011 to 53 in 2012 in a square near to Horley.”

Dr Randle said: “There were substantial annual increases in Meadow Brown numbers within survey squares in Surrey.

“Meadow Browns accounted for 45% of all butterflies seen in Surrey last year.”

She said: “The top three butterflies in Surrey were the Meadow Brown, second, Gatekeeper, and third, the Small White.

“These species comprised 68% of all butterflies seen in the WCBS in Surrey in 2012.” However, she added: “The Common Blue didn’t do well in Surrey last year.

“It suffered a 77% reduction in numbers.”

The WCBS scientific survey is run by Butterfly Conservation, the British Trust for Ornithology (BTO) and the NERC Centre for Ecology and Hydrology (CEH) as part of the United Kingdom Butterfly Monitoring scheme (UKBMS).

It found that last year’s incessant rain prompted substantial grass growth and provided good conditions for some grassland species such as the Meadow Brown, Ringlet and Gatekeeper.

But over-all, 2012 proved to be a wash-out with butterfly recorders seeing 43% fewer species on average than in 2011 during survey counts.

The WCBS involves counting butterflies in more than 700 randomly generated 1km-squares across the UK countryside.

The scheme helps assess the health of butterfly populations across the wider countryside, rather than specially managed hotspots such as nature reserves.

Last year, recorders saw on average 44 butterflies of four species per-survey made over July and August, compared with 2011, when 47 butterflies from seven species were seen on average.

In 2009, an average of 80 butterflies and eight species were recorded per-survey.

The relatively dry start to 2012, followed by near continual rain, saw bumper grass growth, providing some species with an abundance of their favoured food plants.

The Meadow Brown thrived as a result with more than 18,500 counted - almost twice as many as in 2011. The Ringlet also enjoyed a good year and was found in almost two-thirds of squares compared to half of squares in 2011. Another grass-feeder, the Gatekeeper, was also more widespread than 2011.

But the months of unseasonable wet weather proved problematic for many other species.

There were 38 visits when recorders saw no butterflies at all.

Garden favourite the Small Tortoiseshell suffered further declines with less than half the number counted than in 2011. The once-widespread species was present in less than half of the squares sampled.

The Common Blue also struggled and was found in 50% fewer squares than in 2011. The Wall butterfly also suffered following a series of declines and was found in just 4% of squares compared to 9% in 2009.

Dr Randle said: “Last year was fantastic for the Meadow Brown. “However, the over-all picture is that butterfly populations are suffering in the wider countryside and this needs to be addressed urgently.”

Kate Risely, who co-ordinates the BTO butterfly surveyors, said: "Record-breaking rainfall during the summer months affected birds and butterflies alike, and many species suffered a disastrous season. “Credit is due to all the volunteer recorders who braved the weather and collected this valuable data on butterfly populations."

The WCBS is funded by a multi-agency consortium including Defra, the Joint Nature Conservation Committee, Forestry Commission and Natural England.

Dr Randle said: “We are keen for more people to get involved in the WCBS in the South-east. “For information on how to take part, people can contact me, or visit our website - www.ukbms.org/wcbs.aspx - for more information.” Butterfly Conservation is the largest charity of its type in the world, working for the conservation of butterflies, moths and their habitats. It runs conservation programmes for more than 100 threatened species and manages more than 30 nature reserves. Website: www.butterfly-conservation.org