A NATURE reserve in Scotland has reported record numbers of one of the UK’s rarest moth species.
The dark bordered beauty, a rare moth, can only be found in a few places in Scotland – and Inch Marshes Nature Reserve in the Highlands recorded a record number for 2024.
The species, with its yellowish and brown wings, is an endangered species due to the loss of native woodland, increased pressure from grazers, and a lack of diversity in forests.
Inch Marshes nature reserve reported its best year ever for dark bordered beauty moths, more than double the number of moths caught compared to any previous monitoring season.
RSPB Scotland has been working to create more favourable habitats for the species.
A nature enthusiast, Mick A’Court took a sabbatical from his role as an assistant warden on an RSPB reserve in England to travel to Scotland to monitor the dark bordered beauty moth population numbers.
He used a monitoring system that traps moths every night at 18 different feeding locations.
“Each location is trapped at least twice in the four-week period between mid-July to mid-August, which is the moth’s main flight period," he said.
The moth will be trapped and counted at dawn, at 4am, and then released.
“All moths in and around the trap are identified, counted and recorded before being released in suitable nearby vegetation where they can rest out of sight during the day,” said A’Court.
A’Court trapped a total of 12,058 moths of 212 species over the four-week monitoring period.
While sightings of dark bordered beauty moths started off slow they soon ramped up to never-before-seen quantities.
“The first few trapping sessions produced counts of either zero or very few Dark Bordered Beauty moths,” said A’Court.
“On the night of August 5 it had rained at first and then the temperature dropped from 13°C to 8°C, so I wasn’t expecting to find much in the traps."
A’Court found 33 males and one female in a single trap, while in 2023 only 13 were caught.
The dark bordered beauty can often be found in aspen woodland in Scotland, which has declined as a result of deforestation and overgrazing in Scotland.
Aspen trees rarely flower or produce seeds in Scotland, so they spread mainly through shoots from their roots.
These shoots are the main food source for dark bordered beauty moth caterpillars at Insh Marshes.
“Although Scottish woodland cover has gradually increased in recent decades, aspen cover has remained low with just small, disparate populations,” said Julie Ellis, RSPB Scotland Insh Marshes Warden.
She explained that the reserve made sure to have aspen to spread into by suckering.
“We have removed birch saplings in some areas where they might outcompete aspen suckers by shading them out and have even cut aspen suckers to the height apparently used by caterpillars,” Ellis said.
“Ideally, in future, the aspen woodland boundary can ebb and flow naturally so that less intensive habitat management is required.”
The programme provides eggs, larvae and adult moths for introduction into a small number of suitable sites in an attempt to start new populations in other areas of Scotland.
The work is carried out by the Dark Bordered Beauty Steering Group, which is comprised of representatives from Balmoral Estate Ranger Service, Butterfly Conservation, Cairngorms National Park, NatureScot, Rare Invertebrates in the Cairngorms, RSPB Scotland, RZSS, and the support of dedicated butterfly conservation volunteers.
