Northern Devon sand dune invertebrates

All click beetles have a notch on their spine that can snap together and propel the beetle into the air with a loud clicking sound.

Carder bumblebees have very long tongues so that they can feed from long tubular flowers.

The Sandbowl Snail is only known in the UK from Devon and Cumbria.

What we need to do and where

A sandbowl snail moves across a long thing leaf against a blurred background od dead vegetation lying on the floor. The snails dark brown- black head is visible poking outside of the shell with antennae raised. The conical shell appears three or four times the length of the head of the snail and gets darker brown-black towards the tip and is a light brown- amber towards the head of the snail. — Sandbowl snail, Nicola Bacciu

A very long-legged fly specimen is visible against a white background. It has a black face, red eyes, a black man body, and a narrow black rear with white markings. — Lispe consanguinea, Mike Ashworth

1. About

Sand dunes are found across Devon’s coastlines. Five of the largest systems include Dawlish Warren SSSISite of Special Scientific Interest, on the end of the Exe estuary on the south coast and Braunton Burrows SSSI, Northam Burrows SSSI, Croyde (in Saunton to Baggy Point SSSI) and Woolacombe dunes on the north coast.

The habitat mosaics found in the northern Devon sand dunes are especially important for invertebrates and support many threatened species. Braunton Burrows is particularly important (and has been very well surveyed). A few of the rare moths in this group are also found at Dawlish Warren and Thurlestone in south Devon.

See the Coastal wildbelt page for more information on the important dune habitats discussed below.

Key pressures and opportunities

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Scrub encroachment

Woody scrub is becoming more dominant on all sand dunes on Britain’s west coast for a number of reasons including increased stability of sand dunes allowing shrubs to grow, reduced grazing, increased atmospheric nitrogen deposition and possibly climate change. As scrub grows the species which need open habitats decline. This is a particular issue at Braunton and Woolacombe. 

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Grazing

A reduction in grazing by livestock and rabbits at Braunton Burrows and Woolacombe has had a negative impact on invertebrates (see above). Grazing at Northam Burrows seems to have benefitted the Sandbowl Snail but very high levels of sheep and pony grazing in some areas are thought to have had an adverse impact on other invertebrates such as rare flies.

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Water levels and supply

Many rare invertebrates, particularly flies and the Sandbowl Snail, depend on wet areas in the dune slacks. The water table of dune systems has often lowered due to drainage of adjacent land (including the historic drainage of Braunton Marshes) and changes to rainfall as a result of climate change.

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A reduction in changes to habitats (dynamism)

There has been a decrease in dynamic processes (shifting sands) across west coast dune systems. The reasons are unclear but may relate to dunes being stabilized by changes in plants due to increased atmospheric nitrogen deposition, climate change and changes in hydrology. Past efforts to stabilise sand movement, often prompted by high levels of recreational activity, have mostly proved harmful to wildlife. 

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Climate change

The increasing frequency and severity of storms can damage sand dunes but can also help in terms of increasing dynamism within the dunes and reducing scrub growth.

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Nitrogen deposition

Increased atmospheric deposition of nitrogen resulting from off-site human activities is leading to increased soil fertility and changes in plant communities. In turn, this impacts on specialist invertebrates (along with rare plants). 

2. What we need to do and where

Devon Special SpeciesDevon Species of Conservation Concern which have been 'shortlisted' as needing particular action or attention. / Groups

See Find out more below for links to more detailed information on this group including management advice and records.

A long black beetle sits on a stalk on a sandy beach. The beetles wingcases have vertical lines.

A click beetle

Dicronychus equisetioides

In the UK this beetle is confined to a series of dune systems along the south Wales coast, Braunton Burrows and Woolacombe Warren, meaning Devon holds the only known English population. Larvae feed on the roots of vegetation in sand dunes.

As with all click beetles, D. equisetioides have a notch on their spine that can snap together and propel the beetle into the air with a loud clicking sound. This can be used to right themselves if flipped over or to evade predators.

Bumblebee perched on dead flower stalks against a green background. The bee has a deep orangey-brown back against a pale yellow body with the other brown markings hidden from view. The legs, eyes and antennae are black.

Brown-banded Carder Bumblebee

Bombus (Thoracobombus) humilis

The Brown-banded Barder Bumblebee has undergone a serious national decline since the 1970s and the Devon population is nationally important. The species is not a sand dune specialist but there is a healthy population at Braunton Burrows and signs of population recovery on the surrounding coast. Carder bumblebees need a range of flowering plants, in particular those with long tubular flowers (the bees have long tongues) but also clovers, peas, mint, figwort and the daisy family. The species nests on or just below the ground among long grass or mossy vegetation. They have a clear preference for extensive, well-connected flowery habitats with rough grasslands.  

Sandbowl Snail

Quickella arenaria

In Britain this wetland snail is only known from Devon and Cumbria. In Devon it’s found at Braunton Burrows and Northam Burrows where it lives on sparsely vegetated sand in dune slacks that are at least seasonally flooded (with freshwater).

The Devon population has declined by 44% in the past two decades. At Braunton Burrows, some of the slacks formerly used have become overgrown by grassland, dense stands of creeping willow and scrub. A 2022 survey located populations of the snail in just two slacks. Some open areas are maintained by creating scrapes.

Another population of Sandbowl Snails has recently been found on Northam Burrows. The active mixed grazing there is maintaining short swards and this, with the creation of new scrapes for Water Germander (see the Sand dunes tile on the Coastal Wildbelt page), has increased the extent of habitat suitable for the snail.

Northern Devon sand dune flies

The north Devon sand dune systems, most notably Braunton Burrows, are of outstanding importance for true flies and support numerous nationally rare and nationally scarce species, including at least five that are threatened, or near threatenedA species likely to qualify for threatened category in the future, perhaps very quickly., with extinction in the UK. These five species are not known from anywhere else in Devon and are listed below (for more details on status see the Devon Species of Conservation Concern spreadsheet).

This group of flies is strongly associated with early successional habitats: shifting sand, open slacks (damp hollows), ponds and short, flower-rich grassland. It includes:

The Spurge Bug Parasite Fly (Dionaea aurifrons), which is only known in the UK from Braunton Burrows and Woolacombe.

Lispe consanguinea was re-found in 2023 where a small stream enters Croyde dunes. It hasn’t been recorded from other UK sites since 1960.

Helina parcepilosa was last recorded in Braunton Burrows in 2019. It’s confined to a few dune systems in south-west England and south Wales, but with few records since 1960.

Coenosia vibrissata was recorded in Braunton Burrows in 2016 and is known from a few locations in southern England on coastal dunes and damp patches in inland heaths.

Thrypticus lichanus is found at Braunton Burrows and is associated with shallow ponds with rushes (Eleocharis and Schoenoplectus). Elsewhere its known from single sites in Norfolk, Cambridgeshire, Dorset and Cornwall.

This group also includes a few species that are, for flies, large and spectacular, such as the Dune Villa Bee-fly (Villa modesta) and the Dune Robberfly (Philonicus albiceps). These species can be used to help engage the public and increase awareness.

The Pied-winged Robberfly (Pamponerus germanicus) was last seen on Braunton Burrows in 2000.

A full review of flies at these dune systems and others (Braunton Burrows is by far the best recorded site as surveys of other sites are rare) is likely to uncover more threatened or near threatened species. There are also many species occurring on the sites that have yet to have their national status assessed, even provisionally.  

Little is known about changes to the distribution and population of flies in this group due to lack of records over time.  However, they’re likely to have declined due to scrub encroachment, lowering of the water table, changes in grazing and reduced dynamism within the dune systems. See Key pressures and opportunities above. Restoration of dynamic processes, whether by mechanical intervention or increased grazing, is a priority. 

See the LNRS profile for sand dune flies in Find out more below for more information.

Orange and sandy striped/patterned moth with a beige-brown head, standing on a leaf

Sand dune moths and butterflies

A number of rare moths are found in sand dunes and primarily recorded in Devon at Braunton Burrows, Northam Burrows and Dawlish Warren. The habitats used by these moths are often very specific and may often not be recognised as being of wildlife value. This group also includes the Small Blue butterfly recorded at Braunton Burrows.

Scarce Violet Beauty (Pancalia schwarzella): In Devon this moth is only known to occur at Braunton Burrows in damp areas not on sand dunes. Caterpillars have been found feeding on the leaves of Heath Dog Violet, Hairy Violet and Wild Pansy growing close to moss. The caterpillar inhabits tubes in the sand.

Silverweed Borer (Monochroa elongella): Caterpillars feed on the roots of Silverweed, causing the plant to wilt. They have only been recorded in Devon at Braunton Burrows.

Coast Straw (Gynnidomorpha permixtana): Caterpillars have been found feeding on the seeds of Red Bartsia. The coast straw is known from scattered locations around the British coast and has been recorded at Braunton Burrows.

Shore Knot-horn (Gymnancyla canella): Caterpillars feed on Prickly Saltwort. They initially feed internally in the stems or shoots and then feed from within a silken web attached to the plant, containing trapped grains of sand. In Devon this species has only been found at Dawlish Warren.
Sandhill Knot-horn (Anerastia lotella): Only found in sand dunes. Caterpillars feed on sandhill grasses, such as Marram, where they construct a silken gallery around the stem bases and roots. They fly in July. Recorded in northern Devon dunes, Dawlish Warren and Thurlestone in south Devon.
Saltern Grass-moth (Pediasia aridella): Caterpillars feed on Common Salt-marsh grass in a silken gallery among the stem bases. The moth has been recorded in Braunton Burrows and Northam Burrows.
Rolled Grass-moth (Pediasia contaminella): Caterpillars feed on a range of grasses but largely Sheep’s Fescue. In Devon, only found on the south coast, especially around the Exe Estuary and Dawlish Warren as well as the East Devon Pebblebed Heaths.
White Colon (Sideridis turbida): Caterpillars feed on herbaceous plants in coastal areas and now largely confined to Dawlish Warren and north Devon sand dunes.
Shore Wainscot (Mythimna litoralis): Like Sandhill Knot-horn, this species feeds on Marram grass and is found in the same locations.
Sand Dart (Agrotis ripae): Caterpillars feed on herbaceous plants, especially Prickly Saltwort and Sea Rocket. Found mainly at Dawlish Warren and dunes in northern Devon.
Small Blue (Cupido minimus): Caterpillars feed on Kidney Vetch. Very locally situated in Devon, main sites are East Devon coast, Torbay coast and Braunton Burrows. East Devon sites tend to be managed naturally by occasional cliff fall or erosion creating the breeding conditions they need.

Actions

Manage dune systems to maintain a mosaic of habitats for rare invertebrates

Manage dunes and surrounding habitats to maintain a mosaic of connected habitats that includes all stages of succession including foredunes, more established areas with Marram Grass, dunes with lichens, dune heaths and wet dune slacks with seasonally changing water levels.
Create early successional habitats such as mobile sand, pools and wet areas in the dune slacks. This can be done in a number of ways including sensitive grazing regimes, pool and scrape creation, rotational cutting of scrub and using groynes to trap sand and create new dunes.
Maintain flower-rich areas to provide pollen, nectar and caterpillar food plants and lightly graze where possible.
Protect areas of importance for key species from recreational disturbance and nutrient enrichment from dog fouling.
Control invasive species.
Translocation of Sandbowl Snails to suitable scrapes should be considered as it’s unlikely they will otherwise be able to colonise newly created pools and scrapes.

Monitoring and awareness:

At Northam Burrows assess the impact of current grazing levels on invertebrates.
At Croyde, survey to map and determine the current extent of habitat for Lispe consanguinea and develop an action plan.
Increase the recording effort for flies at sites other than Braunton Burrows.
Carry out a full review of the dune invertebrates to identify species and groups of particular interest.
Increase awareness of the value of the dune systems for invertebrates and their diverse specialist habitat needs.

Other relevant actions

Other Devon Special Species found in Devon’s sand dunes include sand dune plants, Braunton Burrows lichens, sand dune bryophytes (Rabbit Moss, Large Hookmoss Petalwort). Follow the links below to the relevant species and habitat pages.

Where to focus action

High Opportunity Areas:

Braunton Burrows, Northam Burrows, Croyde and Woolacombe dunes in the Cornwall to Morte Point Coastal Wildbelt.
Dawlish Warren dunes in the Sidmouth to Torbay Coastal Wildbelt.
Thurlestone dunes in the Bolt Tail to Plymouth Coastal Wildbelt.

See Mapping. Use the Search function to find specific sites mentioned and also see the Coastal sand dunes (existing) layer.

3. Inspiration

Case studies

Dynamic Dunescapes 

The Dynamic Dunescapes project, led by Plantlife and National Trust, working closely with Christie Estates and the Ministry of Defence, was a major project restoring open sand and slacks at both Braunton Burrows and Woolacombe, through mechanical intervention, restoration of cattle grazing and removal of non-native species.  

Vast sand dunes with marram grass at Braunton Burrows with a view out to the sea and beach

Where to visit

Always follow the Countryside Code and keep to footpaths and sites that are managed for public access.

Braunton Burrows

Within the North Devon National Landscape, Braunton Burrows is a large and complex dune system found between Saunton Sands beach and farmland. The whole area is protected as a UNESCO Designated Biosphere Reserve due to the rarity of the plant and invertebrates found here.

Find out more by watching the following video: Braunton Burrows: Sands of Time.

Dawlish Warren

Dawlish Warren, along the south coast, consists of multiple different coastal habitats. This diversity supports a wealth of species and makes the site internationally important for wildlife. It’s an integral feature of the Exe estuary’s Special Protection Area (SPA) and Ramsar site designation.