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Hot summer affects London butterfly sightings

By deliar
16th March 2023

Last year’s hot summer led to some of the lowest ever autumn butterfly sightings in north London and Hertfordshire, records show.

A bright spring in 2022 supported early species, stretching out their flight cycles, and leading to a split picture across the year. However, the summer’s heat and low rainfall dried out food plants, cutting off nectar supplies. This damaged prospects for later species.

Numbers fell for many butterflies, including the white hair streak, though researchers welcomed sightings in green spaces in London such as Alexandra Park, Enfield Lock, and Tottenham Marsh.

One bright spot was an increase in numbers of both the holly blue, and common blue, after a drop in 2021. Other butterflies such as the speckled wood remained stable, although the weather had a distorting effect on flight patterns.

Protecting habitat

Alice Roberts of CPRE London commented: ‘We enjoy seeing butterflies in our urban parks and gardens, so this decline in sightings is concerning. We know that 80% of butterfly species in the UK have reduced since the 1970s, reflecting the UK’s decline in biodiversity.

‘The fact that species have declined less fast in urban areas reinforces the huge value of London’s parks and gardens in maintaining populations. By safeguarding London’s green spaces we can help support biodiversity and play our part in attempting to reverse this worrying decline.’

The annual survey is carried out by the Hertfordshire and Middlesex branch of Butterfly Conservation. The branch website welcomes submissions.

For more on saving London’s green spaces see Green space for all – CPRE London

To support work to help create a greener London go to CPRE London fundraising & online donations | KindLink

Silver washed fritillary
Fritillary butterflies have been spotted in north London