Big Butterfly Count: lowest average numbers in its history

Organised by Lulworth-based charity Butterfly Conservation, the annual count provides scientists a snapshot of how butterfly populations are coping – which can, in turn, highlight, issues with biodiversity.

Not only do this year's numbers represent the lowest average of butterflies logged, they also represent a reduction in the average number of butterflies logged per count of -34 per cent in comparison with 2019.

In total, more than 1.4 million butterflies were counted across the UK in the citizen science initiative, which took place from July 17 to August 9.

Dr Zoë Randle, senior surveys officer at Butterfly Conservation said: “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”.

But she added: "Coming so shortly after the recent World Wild Fund for Nature and United Nations 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”.

Dr Randle says 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," she said. "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."

This year also saw the highest number of butterfly sightings ever submitted by the general public with 111,628 participants submitting a record-breaking 145,249 counts this year, an increase of 25 per cent on 2019.

Butterflies and moths are incredibly valuable indicators of the health of our environment, says the Butterfly Conservation.

A charity spokesman said: "Their declines show not only the effects of human behaviour on the world around us but also the changing patterns of our weather. As well as being important and beautiful creatures in themselves, they play key roles in the ecosystems of birds, mammals, invertebrates and plants as food, population controllers and pollinators.

"Their conservation is vitally important."