Grayling Butterfly Conservation in the North Wirral Coastal Park

Grayling butterfly. Photo: Patrick Clement

During August, the North Wirral Coastal Park Rangers and Friends Group volunteers met up with Dave Costello, the Wirral Officer for Butterfly Conservation, to discuss habitat management for the Grayling butterfly in the Leasowe Gunsite dunes.

Dave informed us that until 2 years ago, Grayling were present on two sites in Wirral/Cheshire, namely the Gunsite dunes and Red Rocks in Hoylake. They have not been recorded at Red Rocks for 2 years and are therefore considered to be extinct at this site. This means that the Gunsite dunes is now the only site where this area's rarest breeding butterfly can be found.

Habitat management for other rare invertebrates in the Gunsite dunes such as the Spring mining bee (Colletes cunicularius) has been a key concern for Rangers and volunteers over many years with tasks such as invasive scrub control, mainly elm and poplar, and sand trapping to encourage dune formation being regular activities. One major problem within this dune system is that there is very little naturally wind blown sand from the beach available to replenish the dunes due to the presence of concrete sea defences. This has led to the formation of blow outs, over stabilisation of dunes by excessive vegetation growth and a significant reduction in bare open sandy areas.

New dune formed from imported sand

In the last few years the situation has much improved since the Rangers organised the regular import of many hundreds of tons of wind blown beach sand from further along the coast at Derby Pool where it needed to be cleared as it was blocking vehicle and pedestrian access. Since this activity, which is still ongoing, we now have significantly more open, mobile sandy areas which have formed across the frontal dune areas as the new sand gets blown inland by strong onshore winds with new small hummock dunes continually forming as some of the sand gets trapped by lyme and marram grasses.

Volunteers creating bare sand areas on over vegetated south facing dune

This dune management approach using imported sand has provided to be an essential habitat requirement for the Grayling butterfly, namely the provision of plenty of open bare sand for basking in the sun, together with more sheltered sunny spots with sparse vegetation such as species of fine grasses necessary as larval food plants.

Imported sand spreading into dunes

Dave advised that the adult Grayling's preferred nectar source is Sea Holly which has a fairly sparse distribution within the Gunsite dunes. We are currently in contact with Chester Zoo to see whether they can propagate plants for us from collected seed, to plant in the dunes. We worked with the nursery team at the Zoo several years ago on a similar type of project to extend the rare Isle of Man Cabbage distribution within the Gunsite dunes. The Zoo has already carried out a similar exercise growing Sea Holly at Red Rocks two years ago to replenish the plant's population in the dunes there.

Sea holly

The Rangers and Friends Group volunteers with input from Dave Costello and the local Butterfly Conservation team will continue to carry out a range of habitat management tasks that will hopefully  be of benefit for the survival of not only the Grayling butterfly but also other dune invertebrates. These will include invasive scrub control, creating more open sandy sites especially within warm south-facing dune areas which have become over vegetated, and removing dense areas of coarse grasses from around existing sea holly plants to encourage better wind blown seed dispersal across the dunes.

John McGaw
(Friends of North Wirral Coastal Park)