Durham argus butterfly project on the Durham Coast

A rare butterfly in a unique habitat

As its name suggests, the Durham argus butterfly is found only in County Durham, and it’s an even rarer subspecies of the scarce northern brown argus. In 2016, rangers on the Durham Coast made it their mission to help this little butterfly thrive.

Why the project was needed

Adult Durham argus butterflies feed primarily on wild thyme, while its larvae feed on common rock rose. Isolated patches of rock rose are found on south-facing grassy slopes along the Durham Coast. This yellow-flowered plant is vital to the butterfly’s survival and so this had been the focus of rangers’ efforts to boost the species’ chances of a successful future.

Unfortunately, in the spring of 2015 vandals set fire to large swathes of coastal grassland, damaging or destroying several rock rose sites. National Trust rangers kept a close eye on the recovery of the Durham argus and worked to restore damaged habitats after recording depleted numbers.

Making a plan of action

Ranger Wayne Appleton took the lead on the project which identified and mapped existing, historic and potential Durham argus sites. This provided a solid basis for a more intensive scheme of habitat improvement in the hope that the small core population could be nurtured and potentially grow.

Combining knowledge and experience

The lucky discovery of a report titled ‘Durham argus on the Durham Coast’ in an office bin in 2016 spurred Wayne on in his research. He unearthed further reports carried out by Dr Sam Ellis in 1997 and Dr Dave Wainwright in 2004.

Wayne combined the results of these reports with expert advice from the Butterfly Conservation Trust – as well as his own extensive experience from working on the coast – to create a 5-year plan to bring the Durham argus back from the brink of extinction. This included tasks such as planting more rock rose, wild thyme, red clover and bird's-foot trefoil.

‘I was inspired to do the project simply because of my love for the sites and how special they are. I also feel a massive responsibility to do the project, the sites have been neglected in the past and I now feel as though we have the chance to do something about it.’

– Wayne Appleton, Ranger, Durham Coast

The progress so far

Since the start of the project in 2016, adult butterfly numbers have increased from seven to 48 recorded on our coastal sites, from Blast Beach near Seaham in the north to Lime Kiln Gill at Horden in the south.

We've undertaken scrub clearance across 17 of the 32 current Durham argus habitat sites. So far, we've also planted around 2,500 wildflower plugs with a mix of red clover, wild thyme and rock rose to provide food for adult butterflies and cover for their eggs and caterpillars.

Plans for the project in 2022

In March 2022 rangers and volunteers started sowing, pricking out and potting 7,000 new plants in our own wildflower and tree nursery. We'll be planting these in spring 2023 to increase habitat for the Durham argus and expand wildflower meadows on the Durham Coast.

In autumn 2022 we'll start work on 15 future breeding sites with the help of the SeaScapes partnership.