Barscube Butterflies

This is my local patch – Barscube Hill in Renfrewshire. It guards the south bank of the River Clyde just west of the Erskine Bridge and, although it's high ground doesn't even scrape 100m, it stands out as an obvious high ground feature for miles around. The hill is conveniently split into an east and west side, with obvious differences in habitat character.

On its higher, east flanks, the upland acid-grasslands are heavily grazed by sheep in summer and cattle in winter. On the exposed slopes, the only shrub cover are a few gnarled hawthorns and patches of gorse and broom which fill the stream gorges and hollows. A trig point is located at NS 38893 71525 and offers very grand 360 degree views for such a modest peak. The shot (above) is looking NE just an hour before dusk as the light plays on the Kilpatrick Hills. A glance west would take in the Clyde Estuary, while Ben Lomond and the Arrochar Alps is to your north and the Renfrewshire Heights spread away to the south. Well worth the effort to make the short climb.

The west side of the hill has a much more diverse habitat. It is not grazed by livestock and features moorland and upland heath, with blaeberry and a rich array of acid-loving grasses and flowering plants. Nothing botanically earth-shattering, mind, but a nice spread all the same. There's substantial Rowan on the lower slopes and in isolated patches on the moor itself, a couple of patches of conifers and a fantastic upland pond. It's a great place to explore and it has some decent wildlife.

Since it's rather a dismal day today, I'll brighten things up by looking this time at the butterflies of Barscube Hill.

The hill is notable for its healthy population of Small Pearl-bordered Fritillary, which appear in mid May. Most marshy ground at Barscube has a few, congregating on Marsh Thistle and Marsh Cinquefoil and basking in the rushes. My best day count was more than 100 individuals so my patch is quite important in a regional context for this UK BAP species. It's certainly one of my favourites.

Small Heath is the other UK BAP species, a grassland species that I find notoriously hard to snap! The last two summers have been pretty dismal for this little butterfly, with numbers down 50% and 60% respectively on numbers in 2011 and 2010.

Small Copper is another fairly abundant species, although its numbers really swing from year to year – 2012 was one of my worst on record during my butterfly transects here. This one's nectaring at Sneezewort, but they are commonly associated with Ragworts. I sometimes find the caeruleopunctata form, with blue spots on the hindwing – a very special species.

Green Hairstreak is a Renfrewhire BAP species and has a foothold among the Blaeberry and Gorse, its larval plants, at Barscube. It's hard to spot and never numerous – it's small colonies usually number just a handful on any visit – but it is always a delight to find. An early-flying species, you know when you see the green marvel, that spring is on it's way.

We didn't have Ringlets at Barscube Hill until five summers ago, when the first ones and twos appeared at several grassland sites. Numbers have grown quickly and it is now more common than Meadow Brown, which has always been here. Ringlets have done well despite the last two cold wet summers and it seems comfortable flying even in overcast, cooler conditions when most other butterflies have gone to roost. I've even seen these in flight if disturbed at night.

Meadow Browns don't seem to have been affected by the arrival of Ringlets, even though they occupy a similar grassland niche. It's not uncommon to see hundreds of these on a warm, still sunny July day. There are a number of other common species including Large White and Small White (usually on the lower-altitude slopes of Gleddoch); Peacock and Small Tortoiseshell are more common in late summer and autumn when they visit knapweeds and creeping thistles.

Painted Lady is an irruptive species and was last seen in numbers during the big migration year of 2010, when there were several score at Barscube Hill. This was part of a big invasion in to the UK from North Africa involving millions of individuals. Visible migration is normally a term associated with birds, but I remember sitting near the trig point in late May, counting these strong fliers as they beat their way along the high ground then disappeared north over the Clyde Estuary. Later, there were dozens refuelling at Ragworth, Knapweed and Devil's-bit Scabious in autumn. Typically, I've haven't recorded a single Painted Lady in Renfrewshire in either 2011 or 2012.

Finally, Green-veined White is the most abundant and widespread species on my local patch. I think these are great value butterflies, and the intricate patterning on their hind wings makes them a very nice macro subject. So roll on the spring – and those Green Hairstreaks taking flight again.