Blue Butterflies Brighton

Habitat management at Crowhurst Corner, Brighton

Client: Brighton & Hove City Council; Linkwood Property & Selits

Objective: Habitat creation & management

Formerly an industrial estate that was demolished in the 1980s, Crowhurst Corner belongs to Brighton and Hove City Council (B&HCC) and is now a biodiverse corner of Sussex, offering superb habitat for a range of invertebrate species.

It lies on the northern edge of Brighton’s urban fringe and includes part of a Local Wildlife Site – Hollingbury Industrial Estate Site of Nature Conservation Importance (SNCI).

The Ecology Consultancy has worked on the site for over ten years, conducting surveys, species mitigation, habitat creation and continued practical conservation tasks. The site has seen phased development for business-use by developers Linkwood Property and Selits. To safeguard the wildlife interest of the site and to compensate for the small loss of the SNCI, the Council required extensive habitat creation and the implementation of a long-term management plan, as part of a Section 106 agreement.

Habitat creation included hand-seeding an area of calcareous grassland on specially landscaped terraces that were formed from excavated chalk, mimicking the South Downs in miniature. The bespoke chalk grassland seed-mix was of UK provenance and included a higher proportion of horseshoe-vetch and kidney-vetch to encourage blue butterflies, including one of the flagship species of the South Downs, the Adonis Blue butterfly. This local and national Biodiversity Action Plan (BAP) species was recorded on the site in 2000.

A wild flower rich meadow has resulted, containing a wide range of native species alongside more colourful plants that indicate the site’s brownfield history. There are flowering plants such as dame’s violet, sulphur cinquefoil, goldenrod, opium poppy and tansy. In 2011 (three years after sowing) our ecologists, assisted by Dan Danahar (Brighton and Hove Biodiversity and Conservation Officer, Butterfly Conservation, Sussex Branch), had recorded one of the largest populations of small blues in the county: an estimated 1000 individuals were found in an area of under a hectare. This was thought to be the second of their double brood.

Habitat creation and management at Crowhurst is testament to the fact that if suitable habitat is available and local populations of species such as small blue are present in the locality, they are able to take advantage and increase substantially in number. In 2010 approximately 100 individuals were recorded – a tenfold increase in population has therefore occurred over the last two seasons.

Rough grass banks have been managed for the benefit of small mammals and invertebrates, and have been made use of by small blue males who perch in groups on shrubs or tall grasses in sheltered spots, flying out to intercept females. When mated, the females lay their eggs among flowers of kidney vetch, overwintering as a caterpillar. Both sexes roost in long grass, low scrub and taller herbs, which are also used for shelter in bad weather.

Rabbits help keep the sward short and sheep grazing by B&HCC helps seed germination by disturbing the chalk. An open, grazed sward, with viable seed-banks, can help guarantee the success of important food plants such as kidney vetch and will benefit our smallest butterfly the small blue. We hope that through further management the Adonis Blue will return to this site.

 

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