January 2024: Preparations underway for enhanced butterfly habitats at RSPB Winterbourne Downs

The team working on the Chalk Species Revival project in the Wansdyke area updated us last month on progress so it’s now time to hear what’s been happening with the RSPB team at Winterbourne Downs. It’s not a competition…honest!  

Three people on chalk grassland
Tony Juniper, Chair of Natural England (left) at the RSPB reserve at Winterbourne Downs with Patrick Cashman (right)

Patrick Cashman, Site Manager for Chalk Country Reserves at the RSPB, has been overseeing a set of capital works (physical stuff happening on the ground) at the RSPB’s Winterbourne Downs reserve as part of our Chalk Species Revival project.

Here, Patrick updates us on preparations needed to enhance 29 hectares of chalk grassland habitat for the Marsh Fritillary butterfly. 

There is a huge white earthwork that many say looks like a large chalk sculpture that sits in the RSPB’s Winterbourne Downs nature reserve. So big, it needed planning permission. 

Image shows a brown patterned butterfly sitting on green grass
Marsh Fritillary butterfly at RSPB Winterbourne Down ©RSPB/Patrick Cashman

In effect, this is the centrepiece of the work that we’ve been carrying out at the reserve over the last 10 years. S-shaped, south facing butterfly banks, of which there are now several on the reserve, are playing a crucial role in our ambitions to restore habitats and conditions for the butterflies that rely on chalk grassland wildflower species.  

Butterflies thrive in these open, sunny areas which provide a mix of bare ground and varied plant and herb species. We have seen a real increase in butterfly numbers since we’ve recreated these habitats and funding from Natural England’s Species Recovery Programme is enabling us to fulfil further ambitions.  

Marsh Fritillary butterfly 

I’m organising the works taking place here with the local RSPB team as part of the Chalk Species Revival project. Our work on site will support and increase the resilience of populations of Marsh Fritillary butterflies by putting in place the right conditions for their favourite food. Scabious species, which look a lot nicer than they sound, have purple headed ‘puff ball’ type flowers which bob in the breeze and are found in chalk grassland areas.  

Replacing the water pipeline at RSPB Winterbourne Downs ©RSPB/Patrick Cashman

What’s been happening? 

We’ve chosen a 29-hectare field site. It’s next to the Porton Down Site of Special Scientific Interest, which hosts the local Marsh Fritillary population and once our works are complete, will help the population to move and colonise across a larger area.  

The works will mean more water is available across the fields for livestock, making it possible for us to graze with sheep and cattle. ’Conservation grazing’ as it’s known, enables the right kind of vegetation structure to form which is suitable for scabious species. A defunct 230m stretch of fencing has also been replaced to ensure the cattle can’t escape.  

A 200 square metre chalk scrape has also been created (above) – a bit smaller than a tennis court – that now cleared, will be planted with devil’s-bit scabious, the food plant of the Marsh Fritillary caterpillar.  

Scrapes are created by removing the top level of soil and are simple way of providing bare ground habitat which can encourage a greater diversity of foodplants for butterflies and moths by removing nutrient heavy soils.   

Chalk scrape for butterflies at RSPB Winterbourne Downs ©RSPB/Patrick Cashman

We know that scrapes are effective as we have used this method on other areas at Winterbourne Downs which have helped support Adonis Blue, Chalkhill Blue, Brown Argus and Small Blue butterflies.  

We can’t do this work on our own, so we’re putting together volunteer work parties to help us with the wildflower plug planting: Kidney Vetch for the Small Blue; Horseshoe Vetch for the Chalkhill and Adonis Blues; Common Rockrose for the Brown Argus; and Devil’s-bit Scabious for the Marsh Fritillary.  

Brown butterfly with a white border on its wings resting on a green leaf
Brown Argus butterfly, male ©National Trust Images/Matthew Oates

We have a lot of work to get through over the coming months but we’re looking forward to reporting back on progress, and of course our successes, over the year. 

How can you help? 

 If you’d like to take part, we are looking for new volunteers to join our wildflower planting work parties this Autumn at RSPB Winterbourne Downs. Please contact nicola.quinn@rspb.org.uk