Restoration Of A Small Blue Metapopulation In Warwickshire

Small Blue

The Small Blue underwent an 87% decline in the West Midlands region, becoming extinct in Shropshire, Herefordshire, Staffordshire and Worcestershire. By 2009, only three colonies remained, all on the Southam Lias Grasslands of Warwickshire.

The Small Blue breeds only on flowering Kidney Vetch Antyhyllis vulneraria in a range of dry, sheltered grassland habitats. The most suitable habitat is typically a mosaic of short and tall vegetation with patches of scrub. Abandoned grassland eventually becomes unsuitable because Kidney Vetch is a short-lived perennial and requires some bare ground for regular recruitment of seedlings to maintain its populations. In the Southam Lias Grasslands, the butterfly occurred on limestone grassland, disused quarries, road embankments and disused railways, but many had become unsuitable due to scrub invasion and reversion to woodland.

Project Aim

Between 2009 and 2012 a programme of limestone grassland restoration and habitat creation was implemented on occupied, former and potential sites to reverse the decline of the Small Blue in Warwickshire.

Methods 

  • On limestone grassland sites, scrub management by contractors and volunteers, treating cut stumps with herbicide to prevent regrowth.
  • On sites with good access bulldozers were used to remove very dense scrub, providing bare ground to stimulate germination of Kidney Vetch.
  • Seeding and plug planting of Kidney Vetch on sites with low larval foodplant populations.
  • Creation of butterfly banks on unvegetated sites to provide topographical diversity and different aspects, most of which were seeded or plug planted.
  • Creation of scrapes on rankly vegetated sites left to colonise naturally.
  • Recruiting volunteers to help with practical management and monitoring; establishing volunteer community groups at some sites. 

Read The Full Report

For more detailed information about this project and others across the UK please read the full report: Landscape-scale Conservation For Butterflies And Moths: Lessons From The UK.

Results

  • 35 ha of scrub was removed from 22 sites; butterfly banks and scrapes were created across 16 sites.
  • 25 sites were seeded with Kidney Vetch and over 13,000 plug plants were planted on 14 sites, creating over 30 ha of potential habitat.
  • During the project he number of sites with some suitable Small Blue habitat nearly tripled and the number of flowering Kidney Vetch plants (on which the butterfly lays its eggs) increased by around 75%.
  • The Small Blue responded quickly to habitat improvements, colonising restored habitat on occupied sites, and colonising five unoccupied sites, a 167% increase in the number of populations.
  • Two colonisations occurred in the same year as management was undertaken and two occurred where the nearest occupied site was a 2-3 km distance.

Success!

In this project, the Small Blue has been a ‘flagship’ or ‘umbrella’ species because other butterflies, moths and invertebrates have also benefited from the habitat improvements. The Grizzled Skipper colonised a new site and the Dingy Skipper seven new sites, a 90% increase in the landscape. The Chalk Carpet moth colonised two new sites increasing the number of colonies in the West Midlands region from two to four. Three of Warwickshire’s rarest bumblebees were observed foraging on patches of Kidney Vetch created through the project.

Funders

SITA Trust, CEMEX, Stratford District Council, Network Rail, The Tree Council and Butterfly Conservation Members and Donors.

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