A few weeks after Pearl-bordered Fritillary begin flying in woodland glades they are joined on the wing by their Small Pearl-bordered cousins. Over much of its range the latter is found on rough grassland and scrubby moorland areas, but in southern England isolated colonies occur in forest clearings. Here SPBF favours sites with a warm, damp, sheltered, grassy sward and an abundance of the food plant, Violets. The eastern clearing at Bentley Wood SSSI, Hants (SU264293) is managed to provide such habitat.
Today Ewan and I enjoyed the rare treat of driving south from Oxford under overcast skies to find sunny conditions prevailing at our destination. On walking into the eastern clearing we soon began to see Small Pearl-bordered Fritillary but these flighty little things were not inclined to settle for long. There were probably as many Pearl-bordered Fritillary still present but all had become faded, making the two species easy to tell apart. SPBF also has a lighter, more gliding flight. This mating pair (below) that I found provided the morning’s only photo opportunity. We alerted three other observers, who attracted more people as they arrived and so it went on.
Information boards here tell how cutting small areas each year stops the clearing from becoming overgrown and creates a diverse structure of short and tall vegetation. This provides the right habitat for the requirements of each Fritillary species: PBF favouring warm, bracken-rich areas, while SPBF prefer damper, grassier patches. The latter’s decline in central and eastern England through the latter half of the 20th century is attributed to that period’s great reduction in coppicing.
Following a midday sandwich break we walked around again. The mating pair had by now drawn a group of photographers and the habitat around them was suffering as a result. It was noticeable that the SPBF appeared to be less active in the warmer early afternoon. But on our going into another area of the site two of these attractive little butterflies obliged by perching open-winged close by (below) and that was mission accomplished.
We left site at just before 2pm and went home via Cotley Hill, Wilts so Ewan could see the Marsh Fritillaries there. Most of these were as faded as the Bentley Wood Pearl-bordered, but not all of them (below) and so we had totted up four different Fritillaries in a week.
A forecast weather front appeared to have stalled just to the west of here, and so we stayed in the sheltered area at the foot of the hill. Several Adonis Blue were active amongst plentiful Horseshoe Vetch, and as usual at this butterfly mecca there was a good variety of seasonal species: Dingy and Grizzled Skipper, Common and Small Blue, Brown Argus, Small White, Brimstone, Peacock and Red Admiral. Cotley Hill (ST917427) never disappoints.