Work is well underway to clear scrub and rough grass from internationally important chalk grassland habitats supported by the Isle of Wight National Landscape Partnership. The habitats are home to five Blue Butterflies: Small Blue, Chalk Hill Blue, Adonis Blue, Brown Argus and Common Blue. The clearance works on these south facing slopes along with the installation of improved grazing facilities (cattle corals, fencing, water supplies) will improve the short-grass habitats and foodplants needed for caterpillars to feed and increase nectar sources for the adults.
Over the winter months although there is not much sign of life on the chalk grassland as all the butterflies hibernate as caterpillars, with the exception of Chalkhill Blue, where the egg is left to overwinter. Hibernation takes place either on the foodplant or in the ground nearby. By the time spring arrives, caterpillars begin to appear and feed on their foodplants. The caterpillar or chrysalis, providing food in the form of sugary secretions, are taken underground by ants which protects them from predators. From May to July, adult butterflies begin to emerging, ‘on the wing’ flying in search of food and to mate until September, depending on the species.
Where are the chalk grasslands?
The chalk grasslands run along the central ridge of the island and southern downs around Ventnor. Isle of Wight National Landscape partners: Gift to Nature, Hampshire and Isle of Wight Wildlife Trust, The National Trust and The Garlic Farm have undertaken work on Brading, Knighton, Arreton and Mersley Down.
Brading Down
The Down is home to the special blue butterflies; Brown Argus and Common Blue. Gift to Nature cleared scrub at Brading Down, cutting back long, more vigorous grass on the south facing slope allows the reduction of shade and nectar producing food plants to grow. The cattle corral has also been repaired at Brading.
Knighton Down and Arreton Down
Hampshire and Isle of Wight Wildlife Trust cleared scrub on Knighton Down and upgraded the cattle corral at Arreton Down, bringing effective and traditional sheep grazing to the site. Clearing the south facing sloping site of scrub will allow sheep to keep the grass in good condition for the nectar loving insects. Adonis Blue and Common Blue can be found on Arreton Down.
Mersley Down
The Garlic Farm have been working on soil health improvement benefits for farmers and nature. The recently funded Farming in Protected Landscapes project on chalk downland Mersley Down allowed Highland Cattle and goats access to fresh grazing, contributing to the restoration of chalk grassland for the benefit of blue butterflies. A water system has also been installed and multi-paddock mobile fencing for mob-grazed livestock.
Bonchurch Down
The National Trust have been working to repair and update the goat fence that surrounds the down and keeps the feral goats feeding on the coarse grasses and scrub including the non-native Holm oak. Reducing the scrub, increases the sunlight on the downs, keeping the short south-facing grassland warm for the butterflies to feed and thrive
Connecting the Chalk Grassland
Isle of Wight National Landscape is part of Big Chalk, a national approach to chalk and limestone landscape restoration. The project includes 14 National Landscapes, South Downs National Park and nine National Trails – https://www.big-chalk.org/