Scientists have published a study showing that targeted conservation efforts across 80 per cent of sites where the high brown fritillary butterfly still persists has led to an increase in numbers and the colonisation of new sites.
Like many threatened UK butterflies the high brown fritillary is a habitat specialist and requires very specific conditions to survive from egg to larvae to adult.
“Butterfly Conservation and partners have implemented conservation management to provide more suitable habitat in the four remaining landscapes where the butterfly still persists,” says Dr Sam Ellis of Butterfly Conservation.
“Monitoring has revealed the butterfly has responded positively in some landscapes, including colonising sites where it used to occur and sites where it had never before been present.”
High brown fritillary butterfly. © Iain Leach/Butterfly Conservation
High brown fritillaries lay their eggs on dead bracken leaves, and the larvae feed on violets. They also spend time basking in areas of low vegetation.
Changes to habitats across the UK have left few areas where the butterflies can get everything they need.
However, in some areas this management is not working and the authors of the research have stated that more needs to be done to find out what else may be necessary.
“Something strange is happening in the landscape around Morecambe Bay in North West England. At the same time as the butterfly responds to our management on some sites, overall high brown fritillary numbers continue to decline across the whole landscape,” says Ellis.
“Our research suggests some quite profound changes are occurring to the bracken habitats here,” he adds. “In just 12 years, violets had declined on average by 50 per cent and the habitats had less dead bracken litter but had become more grassy.”
The researchers indicate that the increase in grass cover is potentially due to climate change and could be a larger risk factor in the future.
With this in mind more research is needed to determine what is driving the changes to the high brown fritillary habitat, to see how the butterfly is responding to these changes and test new habitat management techniques.
Read the paper in the Journal of Insect Conservation.