Butterfly identification workshop - event report

19 August 2009, Portland, Dorset

Bob Ford, iSpot biodiversity mentor for southern England, reports on his butterfly identification workshop in a Dorset quarry.

Adonis Blue

Our first OPAL iSpot activity in southern England was held on a beautiful sunny August morning in the limestone quarries of Portland, Dorset.

Our main aim was to draw attention to the diversity of butterfly species found in these abandoned quarries, so we needed a hot, calm, sunny day - and that's exactly what we got!

We started from the Heights Hotel on the top of Portland, where we paused to look at the amazing display of Autumn Ladies'-tresses orchids on the hotel lawn. The first stretch across the high plateau at the northern end of the island produced little more than a few Common Blues and some very tatty Meadow Browns. But as soon as we dropped down into the shelter of the quarries more species began to appear.

Chalkhill Blue

Chalkhill Blues are at their most numerous at this time of year. Wherever their food plant, the Horseshoe Vetch, grew we’d find dozens of these shining blue butterflies. We saw more browns - Gatekeepers and Small Heaths - around the bramble bushes in the sheltered corners of the quarry.

We were pleased to discover the Small Heaths as they have not been common this year. Rounding the edge of a steep, grassy embankment we spied the first Adonis Blues. This species requires very warm habitats and is generally only seen on south-facing slopes in full sun. The middle of August brings the second brood of this gorgeously bright, iridescent blue butterfly.

A Hummingbird Hawk-Moth at the top of the slope reminded us that moths are just as interesting as butterflies - but it never gave us a close view, choosing to buzz around at high speed instead.

Common Blue

In the end we identified 14 species of butterfly in less than 4 hours, including Wall and Marbled White as well as the species already mentioned. We also found a good variety of reptiles - Adder, Common Lizard and Slow-worm - and scores of plant species. The weather was a little too perfect for birds but we did spot a very obliging Little Owl scowling at us from its home in a stack of quarried stone.

The next identification workshop is going to be on Sunday 20 September, looking at the life at low tide in Portland Harbour.

For details of this and other upcoming events see the South West activities page.


Photos © Kay Mantripp/Nature Portfolio