The 2020 Big Butterfly Count dropped to a worrying new low despite a record number of observations by the public.
The summer nature study revealed the lowest average number of butterflies per count since the event began eleven years ago. Yet the number of counts submitted leapt by a quarter to 145,249.
Dr Zoë Randle, senior surveys officer at Butterfly Conservation said: “Coming so shortly after the recent WWF and UN reports on the global biodiversity crisis these 2020 results illustrate the perilous state of wildlife in the UK.
"However, the fact that so many people take part in this exciting citizen science initiative is encouraging and makes a huge difference to our understanding of how the natural world is responding to the crisis it is in. Now we need to see initiatives both here and across the world to put nature on a path to recovery.”
The 15-minute nature study asked people to record 19 target species over three weeks in July and August. More than 111,000 people submitted sightings but the average number of butterflies logged per count this summer was down -34 per cent on last year.
Just 10.6 individuals of the target species were seen per count in 2020 compared with 16.2 in 2019.
But last year’s figures were boosted by an invasion of painted lady butterflies, which was not repeated in 2020.
Dr Randle added: “Unfortunately, this summer has not seen an abundance of butterflies, across the UK. We do see peaks and troughs of butterfly numbers each year. Last year, for example, we saw a huge influx of migrant painted lady butterflies, so the data from the Big Butterfly Count is an important snapshot which, along with our other monitoring schemes, helps our understanding of the rates of decline of butterflies and moths.”
The big winners of 2020 were the large and small white, which were ranked one and two on the UK -wide chart. They both showed increases on last year’s poll, as did the common and holly blues and the small copper. But the other 14 species all saw declines.
Common Blue by Ian Kirk.
The conservation official added: “The fall in butterfly numbers this summer may be due to a number of factors. An unusually warm spring led many species to emerge earlier than usual. So we may have only caught the tail-end of the flight period for many species during this year’s Big Butterfly Count.
"It’s important to look at butterfly trends over longer periods, so our scientists will be using these results alongside our other datasets to get a clearer understanding of what is happening.”
While England largely mirrored the UK trends with a poor year for brown butterflies, there were variations in the other home nations’ results. In Scotland the small tortoiseshell was the most widely counted butterfly. Participants there saw three times as many per count than English observers.
Scotland also saw yearly increases in its brown butterflies, like the meadow brown (100 per cent), ringlet (94 per cent) and speckled wood (31 per cent).
A family take part in the Big Butterfly Count while out in their garden. Picture: Butterfly Conservation.
The small tortoiseshell also topped the chart in Northern Ireland. Like the Scots, they were more likely to see them than the English. Recent studies have shown a substantial majority are in hibernation in South East England when the count takes place, and this may be a result of climate change.
The large and small whites prospered in Wales too along with the holly blue, which leapt up by 80 per cent. But the average number of individual butterflies counted in Wales was down by -51 per cent compared with the previous summer.
However, Butterfly Conservation is buoyed by the number of people who took part in the UK-wide survey. They had a record-breaking count of more than 145,000 and 111,628 people took part.
The charity feels that in a very dark and challenging year, the opportunity for getting out into nature and helping as citizen scientists was very welcome to people who had been in lockdown.
While Butterfly Conservation believes the decline of ecosystems across the world is a cause for great concern, it feels it’s also possible to see the power of joint positive action in this year’s Big Butterfly Count.
The surge in the number of counts can help the charity to focus its work to protect butterflies, moths and the environment. They can do this through a closer understanding of the issues insects face and find solutions to help.
To some people, butterflies and moths may seem insignificant but they are key indicators of the health of our environment.
They play a vital role as a food source, as pollinators and population controllers. Declines can not only signal the impact of human behaviour but it can also reveal changing weather patterns.
Speckled Wood by Bob Eade.
Julie Williams, chief executive officer of Butterfly Conservation said: “A huge thank you to everyone who took part in the Big Butterfly Count this year.
"This important data is so valuable to our ongoing and vital research helping us to understand what is happening to our butterflies and moths so we can take focused action to protect these fantastic insects and conserve them for future generations.”
MAIN IMAGE: A large white butterfly flying over a meadow. Picture: Jack Mortimer.