The State of the UK’s Butterflies 2015 report has found that 76% of the UK’s resident and regular migrant butterflies declined in abundance, occurrence or both over the last four decades.
The report, by Butterfly Conservation and the Centre for Ecology and Hydrology, found that once widespread species now rank amongst the most severely declining butterflies in the UK. The Wall, once a common farmland butterfly across southern Britain, has suffered a 25% drop in abundance since 2005, continuing a longer trend of decline. One of our most abundant species, the Gatekeeper, has experienced a 44% decline in abundance in the last decade and numbers of Small Skipper have been below average in every year of the 21stcentury. The report considers that climate change and pesticides may be playing a more harmful role in their declines than previously thought.
The report also finds that since the 1970s the three common migrant species - Clouded Yellow, Red Admiral and Painted Lady - have all increased dramatically in abundance and in the last few years rare migrants such the Scarce Tortoiseshelland Long-tailed Blue have arrived in unprecedented numbers.
The findings also reveal that intensive conservation efforts have started to turn around the fortunes of some of the UK’s butterflies including Duke of Burgundy and Dingy Skipper and even the UK’s most endangered butterfly, the High Brown Fritillary, has been relatively stable in the last decade.
But despite breakthroughs with some threatened butterflies the report revealed that other species continue to struggle. The long-term decline of the Wood White, White Admiral and Marsh Fritillary show few signs of stopping.
A new scientific study, just published, has found evidence that Neonicotinoid pesticides (Neonics) could be a threat to butterfly populations. Research funding is needed.
The study, by Stirling University in association with Butterfly Conservation and others, has found an extremely close link between increasing use of Neonics and declines in populations of butterflies that commonly breed on farmland. Neonics are a type of chemical which acts a nerve agent for insects. Introduced in the mid-1990s they and are now widely used on crops such as cereals, sugar beet and oil seed rape. They are also sold for use in gardens, so many gardeners may be unwittingly adding to the problem.
Neonics stay in the environment; they reach all parts of the treated crop plant including pollen and nectar, as well as spreading into soils. They get into water courses and adjacent habitats such as field margins and hedgerows where many insects breed. During the last few years evidence has shown that Neonics have been harming bee populations and killing other insects in habitats in and around affected farmland. Pollinating insects play a vital role in our ecosystem and without them our environment and agriculture will suffer.
The pesticides were banned by the EU for two years for use in flowering crops as a precaution while more evidence was gathered. However, they are still used widely in cereal crops. More research is needed to help BC gather the evidence we need to show whether Neonics are a serious threat to butterfly survival. BC has just launched a crowd-funding appeal. You can contribute at http://www.crowdfunder.co.uk/are-pesticides-killing-our-butterflies
The scientific paper is available to read and download at https://peerj.com/articles/1402/