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No. 38 NEWSLETTER Winter 1997

WEST MIDLANDS BRANCH, BUTTERFLY CONSERVATION

 

The Millennium Atlas Project
 

Richard Southwell’s ‘targeting’ strategy to recruit Millennium surveyors surprisingly paid off when he rang me in March. I am averse to being targeted and resistant to volunteering my time for butterfly work. I do have a weakness though in regard to this project and Richard found it. He told me what tetrads he would like covered. This had me immediately mind-eyeing the land, thinking known and unknown habitat, inescapably already in search mode. What clinched it was that the squares bordered a journey I made twice a week.

The countryside between Droitwich and Feckenham is not Alpine meadows, nor even my beloved Dorset or Wiltshire Downs but it too holds out the promise of unexpected discovery. There is also a proprietorial attraction in stocktaking one’s local patch. In fact, as I began to walk my newly acquired lands I became covetous of the adjoining property and on learning that the former recorder was no longer operating, appropriated another clutch of tetrads.

During my first survey year I have enjoyed the freedom of roaming my territory rather than feeling compelled to dutifully complete the list of common species for every tetrad. Although as an economic measure I have adopted the obvious strategy of visiting the most productive habitat in each square several times through the season, I have also made a point of trying unlikely possibilities. Discovering footpaths, bridleways and even a couple of lanes I did not know existed was the pleasant outcome of pursuing the fantasy of overlooked remnants of better-than-average habitat.

Now that I had some quasi-official pretext, a local, private wood that I’d had half an eye on became a feasible target. I made enquiries, contacted the owner and obtained permission to visit the wood. I was initially attracted because the wood had character. It is the remnant of old estate woodland on a hillside. Of the few mature trees remaining, some huge shattered cedars catch the eye. From the butterfly point of view, the promise lies in the extensive open areas with reasonably diverse ground flora and profusely regenerating understory. It was a delight and a privilege to explore in detail a new place and in particular to discover its butterfly ‘spots’. My early season visit was as much about assessing foodplants and nectar potential as appreciating species already on the wing. Later in the year my jottings for July 5th are reminiscent of the innocent enthusiasms of my childhood:

‘Treasures:- woodland border with soaring ashes - 6 treecreeper, great spotted woodpecker, hosts of tits
kestrels’ nest atop the largest cedar, young birds circling, large dense clump of centaury - love that pink!
A comma wood, zipping about and returning to favoured perches along the overgrown rides
ever the hunter, notice sprigs of wych elm in promising location, tarry, sun coming and going, until my instinct is rewarded - little brown butterfly lifts off from the highest leaf & joined by another in a soaring , whirring dance
return later in the afternoon, one of the White Letter Hairstreaks has dropped down to nectar on creeping thistle . . .’

Having an eye for butterfly spots has paid dividends. On three occasions, with Purple Hairstreak, White Admiral and Common Blue, I have had the uncanny experience of seeing the butterfly at the very moment I thought it would be there, as if my wish had been granted. However, three quite unexpected encounters with Brown Argus firmly proved that my eco-psychic powers are not unlimited. On one occasion I was opportunistically scanning a couple of acres of coarse grassland for common species in a hitherto unrecorded square, when I was amazed to see a chasing pair of newly emerged second brood Brown Argus. On the face of it the habitat was unsuitable and owing to recent developments was now entirely isolated.
Discussion on the ‘spread’ of Brown Argus and its apparent increasing range of food plants will surely gain from the Millennium Survey data. At the other end of the spectrum, I was disappointed but not surprised to find only one colony of Small Heath in my twenty-one tetrads. In August 1989 it was prevalent enough in the area to find its way into my garden. The decline of the Wall is well known but my observations during the summer set me thinking about a possible vulnerability in the Speckled Wood, particularly in respect of its liking for overgrown hedgerow habitats in the more southerly counties.. I was surprised not to find the butterfly in a number of what seemed to be ideal woodland settings, that is, the kind of sites where I have found the species in the past, and where it did occur, observation over time indicated little movement beyond fixed small territories. More numerous field observations from the Survey may well serve to link questions of sedentariness /colonising capacity with climactic and other variables involved in the ebb and flow of its national distribution this century (see Maitland Emmet and Heath, 1989, for further details).

As a boy I knew all about the sedentariness of the Marbled White - it only occurred in one small spot on our local patch. It was over twenty years, in the drought summer of 1976, before a major migration from this colony took place. By contrast, in recent years, I have watched the steady spread of Marbled White in the Droitwich area since my sighting of a single butterfly at the end of June in 1989. This summer I was delighted to find another flourishing colony a couple of miles to the south-west and began to speculate about stepping stones from more highly populated areas. Curiously, this site also produced Gatekeepers one week in advance of everywhere else I visited.
One of the major benefits of this kind of survey, it seems to me, is that the single observer can begin to notice patterns and trends by virtue of seeing the same species in many different locations in fairly quick succession. So, for example, this summer for the first time I became aware of the slightly different habitat preferences of Ringlet and Meadow Brown. In one instance there was a sharp contrast. In several cleared woods that I visited, with sunny glades tending to be dominated by soft grass, I found only Ringlets, even though the Meadow Brown’s preferred foodplants were close at hand. If the Meadow Brown has a better year in 1998, it will be interesting to see whether this exclusivity persists. If I saw one Small Tortoiseshell in April and May settling on the warm compacted mud at field entrances, I saw fifty. We tend to think of woodland glades but on the Survey I’ve discovered meadow glades where the coarser grasses gently give way to the delicate fine grasses and with them a greater diversity of nectar plants. A sure sign that you’ve found a meadow glade is that there are nymphalids in residence. Of course, this feature epitomises something of the best that can be expected from the range of grassland between ‘improved’ pasture on the one hand and the few gems of traditional flower meadow on the other, which characterise my survey area. As agricultural Britain goes, I’ve not done badly but even here, paradoxically, I have occasionally noticed a feeling of relief when approaching villages or areas of recreational activity, where the ‘clean acres’ give way to more intricate, jumbled minihabitats that seem to hold the promise of something unexpected. And this for me is what the Millennium Survey has been about.

Peter Darch