Thursday 29 September 2016

Butterfly numbers plummet by 41pc after wet summer, count reveals

Linda Stewart

Published 12/10/2015 | 11:26

Painted Lady butterfly. Photo: Getty images
Painted Lady butterfly. Photo: Getty images
A Peacock butterfly. Photo: Butterfly Conservation/PA Wire

Butterfly numbers plummeted in Northern Ireland this summer due to unusually wet weather.

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This summer's Big Butterfly Count recorded an average of just eight butterflies per count, 41% down on last summer. Most species fell in numbers, and the biggest losers were the Peacock and the Green-Veined White.

However, numbers of the Ringlet Butterfly increased 113% compared to last year. It is one of the few UK butterfly species that thrives in damp weather.

Only the Ringlet, Meadow Brown and Common Blue, as well as migrants Painted Lady and Silver Y moth, experienced a rise in numbers.

Green-veined White numbers fell 79% compared with 2014 and the summer generation of the Peacock barely appeared at all, with numbers down 98%.

Bad weather didn't stop intrepid duo Cadogan Enright and his son Cad Óg from conquering the wild waters of Strangford Lough to seek out butterflies. They managed almost 60 counts by visiting around 60 islands by boat in just seven days.

The Independent councillor for Newry, Mourne and Down and his nine-year-old son braved squalls and blisters in their 40-mile canoe paddle across the lough. Alongside thousands of butterflies, the pair spotted Grey and Common Seals as well as hares and a huge variety of bird life.

Across the UK, the Holly Blue - a common garden butterfly in England and Wales, but a rarity in Northern Ireland, had its best count since 2010, 151% up on 2014.

The butterfly has a boom and bust life cycle due to its relationship with a parasitic wasp Listrodomus nycthemerus. The wasp inserts a single egg into the living Holly Blue caterpillar via its long syringe-like sting. The wasp larva develops in the caterpillar, killing it after it has changed into a chrysalis.

When numbers of both species are low the Holly Blue is able to build its population, but the wasp soon catches up to take advantage of the glut of Holly Blue caterpillars, causing the butterfly's population to crash.

The Holly Blue has been struggling in recent summers, with low numbers recorded, but this year the butterfly bounced back as it enjoyed a temporary advantage over the wasp.

A record 52,000 people took part in this year's count in the UK, spotting almost 600,000 butterflies during the three-week mid-summer recording period.

However, the huge number of counts did not translate into huge numbers of butterflies. On average, people saw 13.4 butterflies per count, compared with 14.7 in 2014.

Butterfly Conservation's Head of Recording, Richard Fox, said: "Undeterred by the lacklustre summer weather, record-breaking numbers of people took part this year.

"More than 50,000 members of the public from Dover to Derry enjoyed 15 minutes immersed in the wonderful world of butterflies, providing important data on how these beautiful insects are faring."

Factfile

Big Butterfly Count top 10 Northern Ireland species ranking

1. Ringlet

2. Meadow Brown

3. Small Tortoiseshell

4. Green-veined White

5. Small White

6. Six-spot Burnet

7. Speckled Wood

8. Common Blue

9. Large White

10. Painted Lady

Belfast Telegraph

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