Big Butterfly Count 2023: wet summer helped butterfly numbers boom - but experts still seeing 'worrying' trend

This year's wetter summer might have been no good for Brits who wanted to hit the beach, but it has paid dividends for the UK's garden butterflies.

The results of the Butterfly Conservation’s 2023 Big Butterfly Count have been released today (15 September), with almost 95,000 participants in the citizen science project seeing more butterflies this year than they have for the past four summers. However, Butterfly Conservation also warned new, 13-year figures have revealed a worrying trend.

In total, over 1.5 million butterflies and day-flying moths were recorded by volunteers who took part in the survey, between 14 July and 6 August. After an all-time low in 2022 of just nine individual butterflies on average spotted per count, this year saw that increase to 12 butterflies.

The most-seen species this year was the red admiral, with 248,077 recorded - a huge increase of 338% on last year. This is the first time the species has ever taken the top spot, with experts believing climate change and warmer temperatures are causing more of the species to skip their winter migrations.

The gatekeeper came in second, with 222,896 sightings. This represented a 12% increase on last year and was a small but welcome, boost for a species that has decreased by 28% since the count began.

The whites took the third and fourth spot, with 216,666 sightings of large whites and 190,506 of small whites, an 11% and 15% increase on 2022 respectively. Holly blue had another good summer, with numbers up 66% on 2022, in keeping with its longer-term Big Butterfly Count trend of a 41% increase.

However, it was not good news for all species. Ringlet, common blue and speckled wood, butterflies all dropped in numbers on last year - and newly released long-term trend data showed the species were all facing long-term declines too.

Since the Big Butterfly Count first started 13 years ago, many species have significantly decreased, the new data showed. Although its numbers hardly changed compared to summer 2022, the green-veined white had the most severe Big Butterfly Count trend in the longer term, a decrease of 61%.

Butterfly Conservation senior surveys officer Dr Zoe Randle told PA that thanks to the huge number of people who got involved, they now knew the effects of last year's drought "were not as bad for butterflies as we had feared".

“The mixed weather this year has helped as there has been an abundance of green food plants available for caterpillars and plenty of nectar-rich flowers for adult butterflies," she continued. "However, while the number of butterflies recorded this summer has been the highest since 2019, the longer-term trends show worrying declines for some of the UK’s most common butterfly species.”

Head of science Dr Richard Fox added that the long-term trends were a further warning sign that nature everywhere was in crisis. “One of the biggest threats butterflies in the UK face is habitat loss," he said.

"While the weather certainly has an impact on numbers from year to year, butterflies, moths and many other species can generally cope with variable weather. What they can’t cope with is habitat destruction.

“Butterflies need a place to live," Dr Fox continued. Butterfly Conservation is urging more Britons to create butterfly-friendly "wild spaces" in their outdoor areas - whether it's leaving a patch of long grass in your garden, to planting a few nectar-rich plants on your balcony - to help turn their fortunes around.

“Nearly 137,000 Big Butterfly Counts were recorded this summer and if every single person who helped with the Count creates a wild space, we can build a UK-wide network of spaces for butterflies to feed, breed and shelter," Dr Fox said.

"By creating a wild space everyone can make a difference and help butterflies and moths thrive.”