Saving the Blues Project Report April 2025

Chalk grassland conservation for the benefit of the iconic five blue butterflies found on the Isle of Wight

Introduction

The Isle of Wight has a complex geology formed by multiple forces including faulting, folding, erosion and ground movement. As well as the fossiliferous strata famous for its dinosaurs, the Isle of Wight is famed for the chalk stacks known as the Needles, heralding the entrance to the unique landscape of the Solent.

Blue butterfly in the foreground feeding on plant food. Grassy field in the background.

These chalk stacks are the obvious stunning statement that chalk is a dominant part of the Isle of Wight’s geology with a chalk spine running west – east through the Island with another formation in the south-east.

Although much has been lost to increasingly intense agricultural practice over the past 6,000 years, a total of 640 ha of calcareous grassland remains with 98% of it in the Isle of Wight National Landscape.

Forming some of the highest points on the Isle of Wight these chalk landscapes have been the gathering places for early occupants of the island, worshipping and honouring their ancestors and more recently has inspired artists and writers showing the important cultural aspect of these landscapes.

The chalk on the Isle of Wight is also a stunning haven for iconic wildlife including 80% of the world population of the endemic early gentian (Gentianella anglica), the only British population of wood calamint (Clinopodium menthifolium) and the five blue butterflies that were the focus of this report.

Nature Recovery

The Isle of Wight is not immune to the biodiversity crisis afflicting the landscape in modern times. Reduction in the quality and quantity of unimproved calcareous grassland has caused reduction in the abundance and distribution of species either dependent or strongly associated with this habitat.

Vast overcast green landscape view, long and overgrown grass and brambles in the foreground, trees in the distance. Three sheep hidden in the grass.

However, a great quantity of the remaining habitat is in sympathetic hands, and it is these landowners, in partnership with Isle of Wight NL, that sought to highlight the challenges surrounding the habitat but also show there are solutions.

Hot on the heels of the adoption of the new Isle of Wight National Landscapes Management Plan and the emerging Local Nature Recovery Strategy, a number of chalk grassland site were targeted for positive management, together with a public engagement project on social media to explain the work, explore the biology of these fascinating and beautiful insects and encourage participation in future projects.

Saving the Blues – Overview

Following an award from DEFRA of a capital uplift in our core grant, IWNL immediately allocated these funds to a nature recovery project focussing on chalk grassland habitats. The project had three aims:

  • Raise awareness among the general public on the value of this habitat
  • Use the five ‘blue’ butterflies found on the grasslands as flagship species for the habitat as a whole
  • Provide funding for three partners to enhance chalk grassland in their ownership totalling 113 ha (18% of the IWNL resource)

A number of other projects with parallel aims were funded through Farming in Protected Landscapes and Access for All and all projects needed to be completed within the financial year (April 24 – March 25).

Newly installed cattle coral, wooden fencing and metal gates under an overcast sky.
Figure 1: Cattle ‘corral’ at Arreton Down – Hants and IW Wildlife Trust

Saving the Blues – Raising Awareness

Given the funding award was made in April the first task was to publicise the plight of blue butterflies on grassland habitats before their emergence from May onwards.

From 10th – 14th June a daily post on our Facebook account highlighted one of the five blue butterfly species: Small blue, Brown Argus, Adonis blue, Common blue and Chalkhill blue. The post explained the biology of the insect, its needs in relation to foodplant and its relationship with ants and the value of the diversity of plants providing nectar and shelter. With these explanations there was encouragement to go to a local chalk grassland site and see these butterflies as they emerge and fly.

In early December, as the projects were being completed, we provided updates with Facebook posts on each project between 30th November and 14th December

Saving the Blues – enhancing the habitat

Three partners sympathetic to the project were approached to see if they were able to take advantage of the funding available. These were National Trust, Hampshire and Isle of Wight Wildlife Trust and Gift to Nature. All were enthusiastic to undertake projects and all were located in the South-east area of the Island (see figure 2)

Ordnance Survey map showing the south-eastern corner of the Isle of Wight. Five blue areas highlighted showing the Saving the Blues project sites
Figure 2: Map of Saving the Blues Project sites on Isle of Wight

The sites were:

a. Bonchurch Down – National Trust
b. Rew Down and Brading Down – Gift to Nature
c. Arreton Down, Mersley Down and Knighton Down – Hampshire and IW WT

    Totalling 113 ha of chalk grassland habitat

    a. Bonchurch Down

      The main task here was to replace the fencing on the Down to facilitate grazing by feral goats which are an important tool in controlling the spread of holm oak (Quercus ilex) scrub on the down

      b. Rew Down and Brading Down

      The project here concentrated on scrub removal and cattle handling facilities which allows more grassland to be managed sustainably into the future as suitable butterfly habitat

      c. Arreton Down, Mersley Down and Knighton Down

      The project on these sites included scrub removal and cattle handling facilities to increase and enhance the areas of good habitat for the target butterfly species

      Cleared scrubland area on a southern facing hillside, green and brown colours. Extinguished bonfire area in the foreground, trees and shrubs in the background.
      Figure 3: Scrub removal on Knighton Down – Hants and IW Wildlife Trust

      Results

      The five summer posts on the ecology of the ‘Blues’ had a social media reach of 2655 with 217 engagements

      The winter posts on progress on the project work had a reach of 980 with 112 engagements.

      With posts from other partners the total project reach was 3635 and an engagement of 492 with 107 views on the website of the project page: Chalk grassland butterflies project – Isle of Wight National Landscape

      The works carried out over the winter of 2024 lead to the fencing of 113ha of chalk grassland habitat on the Isle of Wight. Within these sites two cattle handling facilities (corrals) were installed and over 2ha of scrub was removed.

      In the spring of 2025 surveys will be carried out to see if the work has had a demonstrable effect on the survival of the target species through butterfly transects and other monitoring.

      Acknowledgements

      Thanks must go to the partner organisations with particular thanks to Emma Hunt (HIWWT), Danny Horne (GtN) and David Mears (National Trust).

      Thanks also to Vicky Wilson (IWNL) for her work on publicising the butterflies in the spring and the work being carried out in the winter as well as liaising with landowners and communication teams.

      Green grass in the sun with machinery used for Scrub clearance.
      Figure 4: Scrub removal on Brading Down – Gift to Nature