The reserve of Strawberry Banks is one I have wanted to experience for some years now, so doing so today gave me an evolved way of recording Marsh Fritillary for the 2020 season. An “unimproved” limestone grassland in the Cotswold AONB, it is privately owned and managed in a traditional way, until recently by the Gloucestershire Wildlife Trust. The most well-known butterfly here each year was my quest for this visit. Famously in May 2011 there was an explosion of 15,000 at the site, though in most years numbers are far more modest.
Marsh Fritillary
The reserve (see here) is accessed from a minor road between Oakridge Lynch and Chalford in the highly picturesque Frome Valley to the east of Stroud, Glos. From there (SO 91164 02938) rights of way lead uphill through the ancient Cotswold Beech woodlands of Three Groves Wood on the right and Oldhills Wood on the left. The SSSI itself comprises two steep and wildflower rich pastures on the eastern side of the minor valley of a Frome tributary that flows between those two woodlands.
Once I arrived on site at around 10am it wasn’t long before a first Marsh Fritillary crossed my path, before doing what this species invariably does by posing nicely on a raised stem. All the butterflies I observed today were along the lowest edges of both meadows, and often displayed a preference for nectaring on Buttercups. But the main food plant is Devil’s-bit Scabious. Over the years I have noted some size variation between different populations observed in Great Britain and continental Europe, and today was struck by the relative smallness of this particular cluster.
Though once widespread in the British Isles the Marsh Fritillary declined severely through the 20th century. Having acquired threatened status the species has been the subject of much conservation effort over the past two decades and more recently has enjoyed something of a revival. This Gloucestershire breeding colony is a long established one but populations in general are highly volatile and long term survival will depend upon the maintenance of suitable low-intensity grazed habitats.
There are three main habitat types: damp grasslands dominated by tussock forming grasses, ancient calcareous grasslands usually on west or south-facing slopes in England, and shorter coastal grasslands in other parts of the British Isles. Temporary colonies can also occur either in larger woodland clearings or other grasslands. Smaller isolated clusters are easily impacted by sudden changes to habitat.
Having become extinct here in Oxfordshire during the 1990s, small numbers of MF have in the last two years been recorded on the South Oxon Downs and at Cholsey Marsh in the Thames Valley, though whether this is due to releases remains unclear. The species has also returned to its last known BC UTB location of Seven Barrows on the Berkshire Downs in the current flight season. And a project is now underway to restore Marsh Fritillary to the damp grassland fields of RSPB Otmoor just to the north-east of Oxford (see here).
I feel pleased to have got around to visiting one of the most constant MF populations in southern England in this scenic and uplifting location of Stroud’s “Golden Valley” (see here). Recording scarcer butterflies in new locations is always satisfying as the ongoing pattern of this most unusual of years continues to confirm.
For new visitors to this blog who might have been directed via a specific species search, the different posts presented herein on British Butterflies are regularly referred to. The most consulted items to date are:
Glanville Fritillary @ Hutchinson’s Bank, Surrey – 1066 views
Marsh Fritillary et al @ Cotley Hill, Wilts – 621 views
Large Heath @ Whixall Moss, Shropshire – 408 views
Wood White @ Bucknell Wood, Northants – 254 views
Marsh Fritillary et al @ Battlesbury Hill, Wilts – 228 views
Duke of Burgundy @ Noar Hill, Hants – 225 views
Large Blue @ Daneway Banks, Glos – 222 views
Black Hairstreak @ Whitecross Green Wood, Oxon – 214 views
Heath Fritillary @ East Blean Wood, Kent – 193 views
Pearl-bordered Fritillary @ Bentley Wood, Hants – 186 views
Pearl-bordered Fritillary @ Rewell Wood, Sussex – 178 views
Purple Emperor et al @ Bernwood Forest, Bucks – 168 views
Duke of Burgundy at Noar and Butser Hills – 132 views
Adonis Blue @ Aston Rowant NNR, Oxon – 127 views
Ramblings and Scribblings 