At Leighton Moss we are always thinking about the bigger picture and how we can make our habitats bigger, better and more connected for nature. Here, volunteer Caroline Clay tells us about the important work that we carry out up on Warton Crag and how we are helping to give butterflies a home...
When you think of Leighton Moss, you will no doubt think of reedbed, bitterns, bearded tits and otters. However, for the last 29 years the RSPB have also managed an area of nearby Warton Crag, a 163m high limestone hill, for a wide variety of important and endangered species. Not only do these include important bird and plant species, such as the endemic Lancaster whitebeam tree, but a long list of butterfly and moth species too.
Over the years, 31 butterfly species have been recorded on Warton Crag, with 25 species noted on RSPB transects in 2016. Perhaps my personal favourite is the insensitively named dingy skipper, which may initially be mistaken for a moth in appearance. This small, beautifully brown-grey mottled butterfly can very easily be overlooked as it basks on bare ground or flits speedily past you.
Dingy skippers by Caroline Clay.
In keeping with the downward national trend, the Crag’s populations of nationally scarce and endangered fritillaries are a major cause for concern. Warton Crag is home to four fritillary species, with the high brown fritillary and pearl-bordered fritillary being of most concern. These species are typically found in bracken habitats, where the caterpillars feed on violets growing amongst the decaying bracken litter.
Pearl-bordered fritillary by Caroline Clay.
When the RSPB purchased their section of the Crag, initial management saw fritillary numbers significantly increase. For example, high brown fritillary numbers rocketed from 59 in 1988 to 451 in 1997, a 764% increase in 9 years. However, despite ongoing habitat management, fritillary numbers have continued to fall. Compared to their highest levels in 1993, there has been a 99.5% reduction in pearl-bordered fritillaries to 2016. More alarmingly, only a single high brown fritillary was recorded on the RSPB part of Warton Crag by staff and volunteers in 2016.
Clearly, the time for action to save these fritillaries is now.
The high brown fritillaries need our help by David Mower.
This winter has seen a lot of exciting and vital work into the decline of these precious butterflies. Old maps have been dusted down and transferred to our modern digital mapping systems, allowing us to compare the amounts of each habitat over the years. Three dissertations done in 2016 by Lancaster University students have brought us right up to date with the specific requirements of the pearl-bordered fritillary. Cutting edge LiDAR (Light Detection And Ranging) surveying was undertaken last summer, using a flying laser light source to allow us to produce a current habitat map more precise then we could ever achieve on foot. The LiDAR habitat map is allowing us to identify physical barriers to butterfly movement between key areas of breeding habitat across the Crag.
Two key priorities for butterfly conservation on the Crag have emerged from our research and discussions:
Over the coming weeks our wardens will be spending a lot of time focussing on these two key priorities. They will also be doing the routine management that is done every winter, such as coppicing of hawthorn and gorse. We will show you in more detail what work we have been doing and the reasons why we are doing it in future blogs.
The Saturday work party by Nick Godden.
Another important part of the Save the Fritillaries project this winter has been the start of a new Saturday work party group. So far, our work has focussed on improving breeding habitat connection and removal of scrub where it has crept onto the limestone grassland and pavement. If you think you might be able to give one Saturday a month to Save the Fritillaries, please visit our website.