A new study compiled by Butterfly Conservation and the Centre for Ecology and Hydrology (CEH) estimates that 72% of Britain’s butterfly species have declined, and that even common species numbers have fallen by 24%.
The reason? A loss of habitat is thought to be the main reason for this decline.
From BBC news:
The study looks at data over 10 years, based on two long-running surveys. It analyses how many butterflies of each species there are and also looks at how their ranges have changed.
Among those showing the biggest declines were the Pearl-bordered Fritillary, the Duke of Burgundy and the High Brown Fritillary which saw a 69% fall in its population.
Some of the rarest species are particularly vulnerable to habitat loss as they need very specific conditions to thrive.
But the study also found that even common butterflies, including the Small Skipper, Common Blue, and Small Tortoiseshell saw declines over the decade.
In terms of distribution the study reveals that while in the UK butterfly species have declined by about a quarter over the last ten years, numbers in Scotland have increased by 11 percent over the same period.
Richard Fox, survey manager for the charity, said a number of species were coming to Scotland, but the Comma was a leading example.
“The Borders are the first port of call for butterflies heading north. The Comma is big success story and a particularly striking example because it hadn’t been recorded in Scotland for about 150 years until a decade ago.
“The south of Scotland and the north of England have never had it so good for butterflies. As well as the Comma, the Speckled Wood, Orange-tip, Holly Blue and Small Skipper can now usually be seen in the back garden or while out walking the dog.”
That said, butterfly species that require very specific things from their habitats have also declined in Scotland.
This is especially worrying given Butterfly numbers are used as a general indicator for overall environmental trends and this fall in numbers, coupled with recent studies showing a drop in bird numbers, will likely flag up a wider-ranging biodiversity problem that needs immediate attention.
However, it’s not all bad news. The study did show that focused conservation efforts have helped certain species to recover.
From The Guardian:
The survey did show, however, dramatic recoveries in a few rare species, including the large blue – reintroduced in the 1980s after becoming extinct in this country – which is now expanding its population and range, and the heath fritillary, which has been brought back from the brink of extinction.
Other butterfly species that have seen their numbers rise include the marsh fritillary and the small blue.
Experts are calling for an increase in targeted conservation programs to fight further decline and, in time, reverse the loss of species numbers.