Even as the public sightings of the butterflies rose to their highest since 2010, the number of red admirals in Britain soared over the summer despite the wet weather conditions causing problems for other butterflies, conservationists have said.
Results from the Big Butterfly Count show that sightings of red admirals have reached 73,000 over the three-week survey – a rise of 75 per cent compared to 2016.
This is the highest number since the citizen science count began in 2010. Also the number equals the total number of red admirals counted in the last three years put together.
The surge in numbers saw them come second in the rankings of most commonly seen butterflies in Britain, surpassing the ‘gatekeeper’, which also saw a rise of 24 per cent as compared to 2016.
Similarly, other commonly-seen butterflies also saw a rise in numbers, with the ‘comma’ seeing 90 per cent rise on last year’s count, and the small copper witnessing a surge of 62 per cent. Compared to last summer’s count, the number of common blues rose 109 per cent.
However, on the contrary, the UK’s common white butterflies all declined by more than a third on last year’s count, making it the worst year for the specie. Numbers of green-veined whites were at their lowest since the count began in 2010, with sightings of the other two species at their second-lowest.
On average, volunteers spotted only 11 butterflies each during the count, the worst figure recorded by the charity.
More than three-quarters of the UK’s butterflies have declined in the past 40 years, with some common species, such as the small tortoiseshell, experiencing a dramatic fall in numbers.
While red admirals are now a common sight in British gardens, the butterflies were strictly summer visitors a few decades ago. The butterflies arrived in the spring and summer from the warmer parts of Europe, and bred in the UK before returning south with their offspring for the winter. The butterflies still migrate, but many now overwinter in Britain, making red admirals the most commonly seen butterfly in the winter months.