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The Islay Natural History Trust has just released its report on Islay’s roadside verge project a collaboration with the Islay Development’s Pollinator Initiative.
It has been a two-year study funded by The Botanist Foundation (Bruichladdich Distillery) and supported by the European Social fund and Scottish Government.
Just under 100km of verges throughout the Rhinns of Islay were surveyed during the summers of 2017 and 2018 recording flowering plants and associated pollinators (butterflies, bumblebees, honey and solitary bees, flies and other flower visiting insects).
Every 200m section of verge had a separated survey count with a quadrat recording flower species and the numbers of flowers available for insects and counting the number of insects visiting flowers in each section.
The project employed one full-time botanist for four months and supported two part-time roles through the summers with assistance from four volunteers. Identification of bumblebees was a real learning bonus for enhancing expertise on the island for a tricky set of species.
The wealth of the biodiversity of flowering plants was analysed according to location and associated habitat and management. All routes were surveyed twice across the season resulting in 877 quadrats forming 9,307 species records for the biological records database over 86 1km OS map grid squares.
A total of 167 flowering species were identified, the most diverse sections went through natural habitats, but where verges were left to develop regularly over time, these provided more flowers.
Grazing and early mowing frequently resulted in lower flowering abundance, though grazed swards actually provided some of the most diverse species compositions. These sections, however, did not enable plants to reach or fulfil their flowering potential.
Pollinator recording resulted in records for 1,498 sections where routes were walked three to four times over the season. A total of 1,673 butterflies were counted and 4,147 bumblebees. The green-veined white butterfly was the most numerous, being seen consistently throughout the season and the common carder bee was the most numerous bee species, closely followed by garden bumblebee and white-tailed bumblebee.
Flies not necessarily considered as prominent pollinators were recorded in flowers through 93 per cent of the survey sections. We had records for six solitary bee species and good populations of the rarer moss carder bee and heath bumblebee.
Argyll and Bute Council are supportive of the work we have undertaken and are agreeable to changing their management and cutting practices for Islay’s verges.
There are a few sections which had a profusion of orchids in the middle of the season, particularly Portnahaven and Port Wymess villages and these will be encouraged to be left uncut until the flowers have finished.
We would value the help of anyone interested in helping with this project, collecting seed and helping to redistribute it to other verge areas. We hope that as the years progress the verges will be thick with flowers and visited by many a bumblebee and butterfly.
The full report can be seen on the Islay Natural History Trust website (www.islaynaturalhistory.org) and Islay Development Initiative web pages (www.islaydevelopment.com).