Butterfly numbers drop a mystery, say experts

10 October 2016
 

A huge drop in the number of butterflies in the UK is causing confusion among wildlife experts.

The Big Butterfly Count - an annual survey by thousands of volunteers - recorded an average 12.2 per count, compared with a 2013 high of 23.

Numbers were even lower than a previous slump in the wet summer of 2012, despite far warmer weather.

Butterfly Conservation, which organised the count, said the cause was still a mystery.

Image copyright Butterfly Conservation Image caption Red admirals bucked the trend and showed a huge jump in recorded numbers 

The count involved more than 36,000 people who recorded more than 390,000 butterflies.

The survey has been running since 2010 but the group uses nationwide figures which go back to the 1970s.

Butterfly Conservation's head of recording Richard Fox said: "The overall trend has been a decline but we expect annual variations based on the weather.

"But the fall this year has been shocking and disappointing as the summer weather has been good, and we don't know why. 

"The most extreme thing was the exceptionally mild winter but it is debated if that is a good or bad thing for butterflies."

Read further 

Holly blue butterfly makes a welcome UK comeback after years of scarcity

Azure butterfly bounces back from cyclical decline caused by parasitic wasps with numbers increasing by 151% on last years’ annual Big Butterfly count

Patrick Barkham

Monday 12 October 2015 06.01 BSTLast modified on Monday 12 October 201506.03 BST

A butterfly locked in a cyclical struggle with a parasitic wasp has bounced back this summer after years of scarcity, according to the world’s largest annual insect count.

The holly blue, the only blue butterfly regularly seen flying in gardens and city centres, increased by 151% on 2014 in Butterfly Conservation’s Big Butterfly Count.

It was a welcome return for the azure insect, whose populations boom every six years or so due to its relationship with a parasitic wasp, Listrodomus nycthemerus. The wasp injects a single egg into the living Holly Blue caterpillar via a syringe-like sting. The wasp larva develops within the caterpillar, eventually killing it after it has changed into a chrysalis.

The parasite is completely dependant on the holly blue and can be almost too successful – killing all 100 caterpillars monitored in some scientific studies. Once holly blue numbers have been drastically reduced, the wasp’s population crashes as well.

This allows the butterfly to recover again – holly blues previously boomed in 1976, 1984, 1990, 1996 and more recently in 2010.

This year, the butterflies were seen in St James’ Park and Battersea Park in central London and as far north as Edinburgh.

Despite an often miserable July and August, a record 52,204 people took part in the count this year, spotting almost 600,000 butterflies.

Continued ...

Hot summer helps boost butterflies

UK butterfly numbers have benefitted from the long spells of warm weather this summer, according to a nationwide survey.

The annual Big Butterfly Count attracted a record 46,000 participants who spotted a total of 830,000 insects.

The small white was at the top of the list of sightings, followed by the large white and the peacock.

Conservationists described the results as a relief following the washout summer of 2012.

The survey, organised by charity Butterfly Conservation, invited the public to count how many of 21 common species they can see in a 15 minute period and ran from 20 July to 11 August.

The sustained warm weather over the summer provided "perfect" conditions for a boom in butterflies and day-flying moths according to experts.

"Put simply, butterflies are cold-blooded creatures that rely on the warmth of the sun in order to be active," said Butterfly Conservation's survey manager Richard Fox.

"The hot summer this year meant that some butterfly species, which were in their early life cycle stages when the heatwave began were able to capitalise on it giving rise to high numbers of adults during the count in late July and early August."

Continued

Will UK butterflies recover from 2012 washout? You can help find out.

Can our butterflies bounce back?

July 2013. Sir David Attenborough has warned that UK butterfly numbers are at a historic low and is urging the public to take part in the world's largest butterfly count to assess if species are recovering after their worst year on record.

Butterfly emergence delayed by 3 weeks

This spring, the coldest for 50 years, saw butterfly emergence delayed by around three weeks. The cold start followed washout 2012 - the worst year on record for UK butterflies with the majority of species suffering declines. These difficult conditions, coupled with long-term declines in abundance and population, leave UK butterflies at a historically low ebb with many species struggling in our gardens and the wider countryside.

Help the count

The warm start to July has given many species a much needed boost and Butterfly Conservation is calling for nature lovers everywhere to take part in the Big Butterfly Count to help assess if UK butterflies can recover this summer.

Sir David, President of Butterfly Conservation explained: "The washout weather of 2012 proved a disaster for our butterflies; these conditions, coupled with long-term declines, means there are probably fewer butterflies in the UK than at any point during my lifetime.

Continued

UK butterflies suffering from wet weather - Attenborough asks "How much?"

Butterfly warning as deluge takes toll

July 2012. Butterfly Conservation President Sir David Attenborough has warned that butterflies could suffer serious population crashes this year following record-breaking wet weather.

Sir David is urging the UK public to take part in the world's biggest butterfly survey - The Big Butterfly Count - to see how species have fared following several exceptionally damp months.

April, the wettest for a century, was followed by the dampest June on record which saw flooding across parts of the UK, and the start of July is, if anything, looking even worse. It is feared butterflies may have suffered poor breeding seasons as a result, which could lead to population crashes later this year or next spring.

2007 wet summer caused butterfly numbers to plummet
Conservationists are drawing parallels with the wet summer of 2007 which resulted in widespread flooding across parts of the UK and saw butterfly numbers plummet. Prolonged cold, wet weather delays emergence periods, reduces butterflies' life span and hampers mating and egg laying leading to fewer offspring.

Big Butterfly Count
The results of this year's Big Butterfly Count will help assess the impact of the wet weather on our butterflies.

Read on:  http://www.wildlifeextra.com/go/news/butterfly-2012-weather.html#cr

Cold summer blamed for low Big Butterfly Count numbers

The coldest summer for 18 years has been blamed by conservationists for an 11% fall in butterflies seen during this year's Big Butterfly Count.

More than 34,000 people took part in the survey and recorded 322,000 butterflies and day-flying months.

The gatekeeper butterfly was seen the most, while numbers of common blue were down by 61% on last year's figures.

Butterfly Conservation said eastern Scotland was among the areas worst hit by cold and wet weather.

The charity had expected a bumper count after a warm and dry spring.

But temperatures dropped and there were prolonged spells of rain.

According to the Met Office, 2011 had coolest June across the UK since 2001, the coolest July since 2000 and the coolest August since 1993.

It said the season was the coolest since summer 1993 with only about 10 days when the temperature exceeded 25C widely.

Butterfly Conservation said insects' activity was impaired by low temperatures and heavy rain.

Moths and butterflies are unable to fly, feed, find mates or lay eggs during bad weather.

Richard Fox, Butterfly Conservation surveys manager said: "The fantastic response of the UK public to Big Butterfly Count 2011 has given us a detailed snapshot of how butterflies fared this summer. Twice as many counts were carried out this year as in 2010.

"Unfortunately, the results show that it was a poor summer for butterflies with many species showing declines compared to last year.

"The dismal summer weather, the coldest for 18 years, is undoubtedly to blame, although many butterflies have suffered long-term declines as a result of destruction of their habitats by human activities."

He added: "In bad summers, butterflies need all the help they can get from people to maintain their breeding areas."

The gatekeeper was the most commonly seen species this year, up three places from 2010, but numbers of butterfly were also down by 12%.

The survey also suggested that numbers of small tortoiseshell stabilised during 2011 after a severe decline.

Three times as many small tortoiseshells were recorded per count in Scotland than in England.

Red admirals enjoyed a "fantastic" summer with numbers up by 98%, Butterfly Conservation said.

http://www.bbc.co.uk/news/uk-scotland-14932544