High Brown Fritillary (Argynnis adippe)
Of sea nymphs and hidden valleys …
The Heddon Valley, located in the northwest corner of Exmoor, is a deep, lush wooded river valley running down to the cliffs and tides of the Bristol Channel. It boasts one of the best populations of A. adippe in the UK, which can be found flying from around mid June to mid-late July. June 2016 found me heading west once again and the comfort of the Hunters Inn, my base for three days.
A. adippe is a butterfly over which there is much concern due to its dramatic decline in the UK. Although there has been some recovery at sites which are specifically managed for this butterfly, the High Brown Fritillary is one of our most threatened species whose numbers have plummeted since the 1970s, being extinct over 94% of its former range. Factors causing this decline are said to include habitat loss and fragmentation, a reduction in woodland coppicing - a practice which opens up new areas of suitable habitat that the butterfly is able to colonise once existing sites have become overgrown, agricultural improvement and lack of grazing and traditional forms of bracken management. The woodlands of East and West Sussex used to boast the UK’s leading adippe colonies. Sadly, it has certainly been extinct in West Sussex since at least 1986 and in East Sussex since 1987. Once common and widespread in large woodlands in southern, central and north-west England and parts of Wales, adippe is now confined to a decreasing number of sites including in the Morecambe Bay area of north-west England, North and South Devon (including Dartmoor), Exmoor in South Somerset, and a few sites in Glamorganshire including the Alun Valley near Bridgend.
Easily mistaken for its close relative the Dark Green Fritillary Argynnis aglaja, the two species are most easily distinguished by their undersides, where A. adippe has a row of brown spots between the outer margin and the silver spangles, which are missing in A. aglaja. A less-reliable identification guide is that, as its name suggests, the High Brown Fritillary has a predominately brown hue to the underside, whereas the Dark Green Fritillary is predominately green. The two species often fly together making a positive identification almost impossible unless the butterfly is at rest.
Two images of males above with more to process when time allows ...
Pratt, C. R. (2011). A Complete History of the Butterflies and Moths of Sussex. Peacehaven, East Sussex: Colin R. Pratt, 2, pp. 267-272.