The latest update from Michael Walter:
Memories can be very short and extremely fickle. A bumper season for heath fritillary in June and a good number of red admirals in people’s gardens in August and September was enough to convince most observers that it had been a good butterfly year. Far from it: certainly, in Blean Woods, it was undoubtedly one of the worst ever, with a dearth of whites, few spring brimstones, only the occasional common blue, large skipper and small skipper, and no brown argus. Worst of all, the bread-and-butter species – ringlet, meadow brown and gatekeeper – which bulk up the numbers in July and August, were remarkably thin on the ground; there hasn’t been a worse year since 1982 for ringlet, 1988 for meadow brown and 2016 for gatekeeper. My vegetable-growing successes and failures this year can certainly be put down to the on-off summer, with raspberries benefitting enormously from the wet conditions in May and June, whereas sub-tropical sweet corn and courgettes struggled with the often sunless conditions: it seems likely that many butterflies and other insects also had difficulty coping with the unseasonal conditions.
A clouded yellow on 5th September was my first record in the wood of this European butterfly since 2013. This is an extremely erratic visitor to England, with just occasional years when there is a small invasion, and many intervening seasons when few or none are seen. Unable to tolerate our damp winters, its occurrence in England is entirely dependent on fresh immigrations. Influxes have tended to be at very roughly ten-year intervals, so I think we must be well overdue for another summer when we can thrill to the sight of good numbers of these deep yellow butterflies that make brimstones look rather anaemic! Seeing such exotic butterflies floating over favoured fields of clover certainly raises the spirits.
I have been monitoring the Blean Woods butterfly transect since 1982, and in the ensuing forty years there have been numerous highs and lows, but one of the few certainties is that I will always record speckled woods at the junction of sections 14 and 15 (the route is divided into 15 sections for the purposes of monitoring). Although a widespread butterfly in shady, woodland areas, the speckled wood is remarkably uncommon in Blean Woods, and yet, year after year, I always see a few at this sectional junction. This season was no exception, and on 5th September I saw no fewer than four at this point – a high count for the wood, and all the more remarkable after such an indifferent butterfly year. Males are very cantankerous, flying up in combative whirls to preserve their one sunny resting place from rivals. The caterpillars feed on a variety of grasses, so the speckled wood’s addiction to this tiny corner of the wood is presumably not related to the availability of suitable plants. Admittedly not one of our more colourful butterflies, it nevertheless has an interesting history. From being a widespread, if not common, butterfly in the first half of the 19th century, it all but disappeared from most of the country early in the 20th century, slowly recovering over the next hundred years to reoccupy most of its former range. Better able than any of our other butterflies to tolerate shady conditions, it may well have benefited from the decline in coppicing that began in the first half of the 20th century, and which led to many woods becoming much less sunny.
The local RSPB group is resuming its indoor meetings, which are now held in Blean village hall at 7.30pm on the second Friday of the month through to April. The October talk by Dan Tuson will be on “25 years of wildflower grassland creation in East Kent”. All are welcome to attend. Admission is £5 for non-members, but sign up on the evening and get in for just £4.
Clouded yellow (bottom) and small copper (top right)
Photo courtesy of Glynn Crocker
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