Excursion to Carman Muir, Renton, West Dunbartonshire

On Sunday 15th May a joint field trip between our branch of Butterfly Conservation and the Glasgow Natural History Society was lead by Keith Futter at Carman Muir to look for Green Hairstreak butterflies.

Although the sun came out the wind was chilly at times. The cooling effect of the wind was reduced in a sheltered stream gully which is where most of the Green Hairstreaks were found. Several males were seen defending territories along the gully and frequent spiral flights between combatant males occurred.

Neil Gregory had brought a butterfly net along which enabled us to catch a Green Hairstreak and look at it in very fine detail. Without harming the insect we were also able to see the dark brown inner wing surfaces, something which you do not see in the wild as the butterfly always rests with its wings shut. The butterfly was then released unharmed.

The habitat at Carman Muir is open heathland with occasional bog pools. The heathland is well grazed by sheep and fires on the moor are common. The resulting vegetation, including Blaeberry, the Green Hairstreak caterpillar food plant, is often stunted. Despite the Blaeberry being typically under 10cm tall it seems sufficient for the needs of the Green Hairstreak. In total we observed twenty or so Hairstreaks, many of which were in good condition without showing signs of wing damage due to ageing.

Other butterflies and moths seen during our walk included the Peacock, Orange Tip, Green-veined White, Common Heath Moth, Brown Silver Line, Emperor Moth and the caterpillars of the Drinker Moth and Garden Tiger.

Throughout the walk two Cuckoos were frequently seen and heard and a large Brown Hare was another welcome sight. Other interesting natural history observations included a Water Scorpion, Large Red Damselfly, Round-leaved Sundew, Common Butterwort and Marsh Lousewort.

Overall the trip was successful and the ten people that attended were rewarded with fine views of Green Hairstreaks at close range in their natural habitat.

Carman Muir view of habitat taken by Keith Futter

KF