The bigger picture

The large blue butterfly has an amazing home at Daneway Banks with plenty of happy red ants (Myrmica Sabuleti) to adopt the predatory caterpillars and lots of wild thyme and marjoram for them to feed on and lay their eggs. However, even with the best habitat management practices in place there is still a limit to the number of large blues the nature reserve can support (1). If we want populations of large blues to keep growing we need to think on a bigger scale, making sure there are more areas of suitable habitat nearby for them to disperse to and be able to colonise (2). So how are we helping to do this?

The Golden Valley

Daneway Banks sits within the Golden Valley, one of the five beautiful valleys situated around Stroud. It is known for its unimproved limestone grasslands on steep south facing slopes that soak up the warm summer sun. As well as these grasslands, the Golden Valley also holds a range of different habitats from ancient woodlands to rivers and water meadows. Many of these are important sites for wildlife or, with the correct management in place, have to potential to be. For this reason, the Golden Valley is one of 10 Priority Landscape Areas that we have identified within the county and are focusing to help increase and connect suitable habitat for large blue butterflies and other wildlife (3).

This reconnection of suitable habitat on a landscape scale is particularly important for the large blue butterfly, as it is a habitat specialist and finds it harder to disperse to new areas in an increasingly fragmented environment (4). Only being found at a small number of sites in the UK they are also more susceptible to changes in climate, increasing the risk of local extinctions (2). The large blue mostly stays within a small area, but some have been known to disperse 2-3km (5). If you compare this to the monarch butterfly which can travel thousands of kilometers (6), it’s a miniscule distance. So, the more high-quality habitat available to the large blues within a couple of kilometers, the more likely they will be able to colonise new sites successfully and reduce the risk of local extinctions if their current homes become unsuitable (7).

Working outside our nature reserves

We’ve learnt that the large blues are a picky bunch and won’t settle for just any old grassland they come across. They need specific requirements to be met before they are happy with their new homes, not in the least the availability of their food plants and short grass in the spring to keep their red ant hosts happy (8).

This is where we come in. In the Golden Valley we are working with landowners to helping manage areas outside our nature reserves, to help the large blue butterfly and other species. This includes making sure the correct grazing regimes are in place, removing large areas of scrub, and creating softer borders between habitats so there is a smoother transition in which wildlife can move from one to another (9). Although some of this is geared towards helping the large blue disperse through the landscape, we are also targeting other species, and alter the management regimes in place depending on the species and their requirements (10). This includes the marsh fritillary, pearl bordered fritillary, the hazel dormouse and adder. As well as these few targeted species, the overall change in habitat management of these areas will benefit many species living within the Golden Valley (11).

Woodlands and wetlands

Our focus extends beyond the grasslands within the Golden Valley to the many other habitats that provide a wide range of homes for a variety of different species. In comparison to the green grassland of Daneway Banks, characterized by its yellow meadow ant mounds and sea of yellow and purple flowers, just next door are two of our other reserves, which hold a different appeal if no less magical. These are Siccaridge Wood, an ancient, coppiced woodland; and Sapperton Valley, a mixture of water meadows, woodland, and part of the derelict canal.

Siccaridge Wood boasts many interesting species of its own, and walking along the winding footpaths you will see and hear a variety of wildlife. With the large nests of wood ants dotted along the path that look like small mountains and seem to come alive with the constant movement of the ants. The hazel dormouse uses the hazel coppice and young beech trees to run around the woodland, moving between the interconnecting branches above your head (12). They collect the bright green leaves from nearby trees to make their cosy breeding nests and will snooze the day away safely tucked inside them. Butterflies move along the sunlit corridor from speckled woods and peacocks to silver-washed fritillaries and white-letter hairstreaks. A small population of pearl bordered fritillary’s can be found warming themselves in the woodland glades and laying their eggs on violet leaves (13).

On the other hand, Sapperton Valley provides a tranquil walk along a disused canal and water meadows, both of which are filled with colour and life at this time of year. The derelict canal is filled with aquatic vegetation from the marsh marigold and yellow iris to the large dock, and fool’s watercress, all providing shelter for the many aquatic invertebrates that hide among them. Where the canal and river run close together you may spot the bright blue and orange of a kingfisher resting on a branch. On the other side of the path, we have felled trees into the water meadows to reduce flooding further downstream and improve biodiversity within the reserve (14).

Connecting fragmented habitats

Woodlands and wetlands like Siccaridge Wood and Sapperton Valley are managed differently to grasslands like Daneway Banks and can provide a dazzling number of different habitats for wildlife. By opening up footpaths and glades in the woodland to let more light in and creating a mixed age range of hazel coppice, we can create different types of habitats that will be colonised by different species, depending on their tolerance for shade and sunlight (15). This increases the sunlit corridors for butterflies to move through and adders to bask in (10). As well as the open woodland paths of Siccaridge Wood, the disused Severn and Thames Canal and River Frome running through Sapperton Valley can also provide ideal corridors for wildlife such as large blues to move through. Providing more habitat specific species like them an easier way to disperse through the landscape, connecting fragmented habitats together.

It’s important that we manage a wide range of habitats within the Golden Valley to help species such as the large blue butterfly disperse and establish new homes which meet their needs, increasing their resistance to climate change. Our nature reserves only make up a very small amount of land in the Golden Valley and by looking outside them, working with other landowners and partners, we can increase the impact we make, connecting the landscape across Gloucestershire to help large blues and other wildlife thrive!

⁽¹⁾ We co-own Daneway Banks with the Royal Entomological Society.

References

1. Young, C.C. (1998). Defining the Range: The Development of Carrying Capacity in Management Practice. Journal of the History of Biology, 31(1), p61-83.
2. Saura, S. et al., (2013). Stepping stones are crucial for species' long-distance dispersal and range expansion through habitat networks. Journal of Applied Ecology. Vol 51(1), p171-182
3. Gloucestershire Wildlife Trust. Estate Review 2020. Downloaded from: https://www.gloucestershirewildlifetrust.co.uk/estate-review-2020 [Accessed on 14/06/21]
4. Ewers, R.M. & Didham, R.K. (2007). Confounding factors in the detection of species responses to habitat fragmentation. Biological Reviews. Vol 81(1), p117-142
5. Warren, M. & Wigglesworth, T. Butterfly Conservation Large Blue Maculinea Arion Factsheet. Downloaded from: https://butterfly-conservation.org/sites/default/files/large_blue-psf.pdf [Accessed on 14/06/21]
6. Croteau, E. K. (2010). Causes and Consequences of Dispersal in Plants and Animals. Nature Education Knowledge, Vol 3(10), p12
7. Thomas, J.A. et al., (2011). Evidence based conservation of butterflies. Journal of Insect Conservation. Vol 15(1-2), p241-258
8. Thomas J.A. (1995) The ecology and conservation of Maculinea arion and other European species of large blue butterfly. In: Pullin A.S. (eds) Ecology and Conservation of Butterflies. Springer, Dordrecht.
9. Ӧckinger, E. et al., (2012). The landscape matrix modifies the effect of habitat fragmentation in grassland butterflies. Landscape Ecology. Vol 27, p121-131
10. Bubová, T. et al., (2015). Land mangement impacts on European butterflies of conservation concern; a review. Journal of Insect Conservation. Vol 19, p805-821
11. Randle, Z. (2009). Maculinea arion as an indicator of rare niches in semi-natural acid grasslands in South West England and the role of Myrmica species of ant. University of Southampton, School of Biological Sciences, PHD Thesis, pp181
12. Bright, P.W. & Morris, P.A. (1991). Ranging and nest behaviour of the dormouse, Muscardinus avellanarius, in diverse low-growing woodland. Journal of Zoology. Vol 224(2), p177-190
13. Tomlinson, D. et al., (2020). ‘Pearl-bordered Fritillary’. In Britain’s Butterflies, Princeton: Princeton University Press, p112
14. Thomas, H. & Nisbet, T. (2012). Modelling the hydraulic impact of reintroducing large woody debris into watercourses. Journal of Flood Risk Management. Vol 5, p164-174
15. Buckley, P. (2020). Coppice restoration and conservation: a European perspective. Journal of Forest Research. Vol 25(3), p125-133