Big Butterfly Count 2021 results – crisis time

21st October 2021

The lowest ever number of butterflies and day-flying moths was recorded

A wildlife charity has warned that the UK’s butterflies are in crisis after the lowest ever numbers were recorded in the Big Butterfly Count 2021.

Butterfly Conservation runs the annual Big Butterfly Count, which ran from July 16 – August 8. The overall number recorded per count is at its lowest level since the count began 12 years ago. Both butterflies and moths are important indicators of environmental health, and a decline is a serious cause for concern.

Despite the low butterfly numbers and relatively poor weather, more butterfly counts were submitted than ever before. More than 150,000 counts were logged – more than 38,000 hours of butterfly watching. Compare these with 2016’s results.

Big Butterfly Count 2021 – more counting, fewer individuals

Dr Zoë Randle, Butterfly Conservation’s senior surveys officer, said: “On average, people counted nine butterflies or moths per count. This is down from 11 in 2020, and down again from 16 in 2019. More counts are undertaken and submitted year on year, but it seems that there are fewer butterflies and moths around to be counted.”

Some of the UK’s most-loved species recorded falls in numbers. The Small Tortoiseshell had its third-worst summer in the count’s history and shows a significant long-term decline. Peacock butterflies suffered their lowest numbers since 2012.

It wasn’t bad news for all species, with the Marbled White and Ringlet bouncing back from 2020’s low numbers. Butterfly Conservation scientists warned that last year’s sunny spring allowed them to emerge earlier and 2021’s results are more typical.

‘Worst year since start of the count’

Dr Randle added: “Some of the UK’s butterflies have more than one generation per year, meaning we would see adult butterflies in spring and summer. The majority of these double-brooded species experienced their worst year since the start of the count in 2010.

“Weather changes are likely to be the cause of this. March 2021 was warmer than average, which would have stimulated activity. However, May was very wet which will have hampered feeding and breeding. These combined weather effects are likely to have reduced the spring generation. This has knock-on effects for the second generation in the summer.”

Julie Williams, CEO of Butterfly Conservation, said: “Since 1976, 76 per cent of butterflies have declined in abundance or distribution. The downward trend continues. We have come to accept that encounters with butterflies, moths and other wildlife are unusual, delightful but infrequent.

Big Butterfly Count 2021 – plan for change

“It doesn’t have to be this way. We are pledging to halve the number of threatened butterfly and moth species in the UK, double our impact on landscape restoration, and galvanise people to create new wild spaces for nature. Join us to create a world where butterflies and moths thrive and can be enjoyed by everyone, everywhere.”

To find out more, visit www.butterfly-conservation.org.