Great Breach and Copley Woods: Conservation Efforts for Rare Butterflies
Located near Compton Dundon, Great Breach and Copley Woods serves as a vital sanctuary for local biodiversity. Owned and managed by the Somerset Wildlife Trust, this area is recognized as a Nature Conservation Review Woodland Site. Due to its significant invertebrate population, it has been officially designated as a biological Site of Special Scientific Interest (SSSI), a status reserved for areas of high conservation value.
[ไม่มีภาพประกอบ]
Key Facts
- Management: Owned and managed by the Somerset Wildlife Trust.
- Status: Biological Site of Special Scientific Interest (SSSI).
- Funding: National Lottery grant awarded in April 2017 to Butterfly Conservation.
- Target Species: Brown hairstreak (Thecla betulae) and Large blue (Phengaris arion) butterflies.
- Habitat Focus: Blackthorn hedges and limestone grasslands.
The Brown Hairstreak Recovery Project
The brown hairstreak (Thecla betulae) is a butterfly closely tied to woodland edges, scrub, and hedges rich in blackthorn (Prunus spinosa). Historically, the annual cutting of hedges via flailing has contributed to the decline of this species.
To reverse this trend, conservationists shifted hedgerow management from annual cutting to traditional laying—a method of weaving live branches to create a denser, healthier hedge. This change has increased the availability of young-growth blackthorn, which is essential for egg-laying females. The success of this approach is evident in the data: egg counts increased at six sites, remained stable over three winters at those same locations, increased at three other sites, and saw the species return to two additional sites.
Identifying the Brown Hairstreak
One of the most effective ways to monitor this species is during the winter, when white eggs are visible on the black twigs of the blackthorn plant.
The Complex Life Cycle of the Large Blue
The large blue butterfly (Phengaris arion) requires a highly specific and complex environment to survive. Its life cycle involves a fascinating relationship with both plants and insects.
Initially, the larvae feed on thyme (Thymus vulgaris) and marjoram (Origanum majorana). However, the larvae later employ a survival strategy where they trick red ants (Myrmica sabuleti) into believing the larva is an escaped ant grub. After overwintering inside the ants' nest, the larva feeds on actual ant grubs before pupating in early June.
Habitat Restoration and Expansion
To support the large blue, 8 hectares of limestone grassland were restored through scrub cutting by volunteers and contractors across thirteen locations. To further boost food sources, Bridgwater College and Groves Nursery grew 2,500 thyme plug plants for five of the sites, while marjoram seeds were sown in cleared areas. These efforts yielded positive results: by 2019, the large blue was found at ten sites, an increase of four since 2017.
| Species | Primary Habitat | Key Intervention | Result |
|---|---|---|---|
| Brown Hairstreak | Blackthorn Hedges | Traditional hedge laying | Stable or increased egg counts across multiple sites |
| Large Blue | Limestone Grassland | Scrub cutting & planting thyme/marjoram | Presence increased to 10 sites by 2019 |
Frequently Asked Questions
Why is Great Breach and Copley Woods an SSSI?
It is designated as a biological Site of Special Scientific Interest because of its important invertebrate population.
How does traditional hedge laying help the brown hairstreak?
Traditional laying increases the amount of young-growth blackthorn, providing more suitable locations for female butterflies to lay their eggs compared to annual flailing.
What is unique about the large blue butterfly's life cycle?
The large blue larva feeds on thyme and marjoram before mimicking an ant grub to enter the nest of Myrmica sabuleti red ants, where it overwinters and feeds on ant grubs.
Who provided the plants for the large blue habitat restoration?
Bridgwater College and Groves Nursery grew 2,500 plug plants of thyme to increase available foodplants on five of the conservation sites.