Since 1975 no fewer than 46 species of butterfly have been recorded at Noar Hill. Although it is likely that no site of comparable size has surpassed this tally during that period, it must be emphasised that the figure in part reflects the butterfly richness of East Hampshire together with the intensity of butterfly recording. The maximum number of butterfly species that has been recorded on Noar Hill in a day is a staggering 30 – half the UK fauna!
All told, it is probable that 36 species of butterfly have bred on or adjacent to Noar Hill since 1975, though the tally was seldom in excess of 31 at any one time. The term ‘adjacent’ is important, as several common species breed only intermittently or in low numbers on the actual reserve, though they breed annually on the surrounding land. This category includes Peacock, Small Tortoiseshell, Large White, Small White, Green-veined White and Orange-tip, all of which are seen on the reserve annually, sometimes in numbers. Some species are intermittent residents on Noar Hill: as examples, Dark Green Fritillary and Brown Argus, which seem to colonise during good summer sequences, only to vanish during runs of poor summers.
The main finding of forty years of study is that Noar Hill's butterfly fauna has been in a state of flux throughout that whole period. There has been little constancy, despite and sometimes because of nature reserve management. Nearly all species have been subjected to significant population swings, and nearly all the true resident species have experienced population fluctuations of an order of magnitude or more. This may be the norm for butterfly faunas at site level, for status and distribution are dynamic.
Only Essex Skipper has become truly established since 1975, colonising spectacularly during the mid-1980s, though Purple Emperor may now be breeding regularly there at a low population level. The latter can be viewed as a negative indicator species for a chalk grassland site, being a scrubland species! Silver-washed Fritillary has also increased in frequency on the reserve, breeding in the adjoining hanger since major changes were inflicted by the great storms of 1987 and 1990.
These gains can be countered by some losses. Grizzled Skipper was resident up to 1976 but then died out, seemingly because of the adverse impact of the 1976 drought on its Wild Strawberry foodplant, which frazzled up and never recovered. The butterfly has scarcely been recorded since. In keeping with much of inland central southern England, the Wall Brown, which was moderately frequent on the reserve in most years until 1985, disappeared as a breeding species then and now occurs very rarely. In addition, Small Pearl-bordered Fritillary bred successfully in low numbers on Noar Hill between 1981 and 1983, when there was a large population in the nearby Oakhanger woods.
This last example reflects the butterfly wealth of the general area during the forty years, as do records of four Hampshire resident species which have only been recorded at Noar Hill as occasional strays (Silver-spotted Skipper, Pearl-bordered Fritillary, Marsh Fritillary and White-letter Hairstreak). In addition, I was accosted by a Large Tortoiseshell on the reserve in 1985, at a time when the butterfly had some form of status in the nearby hangers. Furthermore, several Silver-studded Blues were recorded in 1976, after major fires on the nearby heaths, and Grayling was recorded as singletons in 1976 and 2000. But Noar Hill's greatest moment occurred in 2013, when Tony James recorded a specimen of the continental subspecies of the Swallowtail whilst walking the weekly butterfly transect! The insect was almost certainly an immigrant, as several others were seen in the South-east during that memorable summer.
Some important butterfly foodplants are either absent from, or rare on, Noar Hill. Horseshoe Vetch and Devil's-bit Scabious, the main foodplants of three key butterfly species strongly associated with chalk grassland (Chalkhill Blue, Adonis Blue and Marsh Fritillary), are absent, and there is barely sufficient Common Rockrose and Honeysuckle for their associated butterflies (Brown Argus and White Admiral). Nonetheless, Chalkhill Blue does appear sporadically, mainly as solitary adventive males during hot summers. Also on the debit side, scarce migrant species are recorded only uncommonly at Noar Hill, doubtless due to its distance from the coast. Clouded Yellow does, though, appear intermittently and occasionally produces a weak summer brood.
The SSSI citation states that Noar Hill is of particular importance for populations of Duke of Burgundy, Brown Hairstreak and Small Blue. For such a small site, Noar Hill is unique in supporting populations of these three species. Noar Hill's butterfly species assemblage is, in effect, strikingly unusual for both species-presence and species-absence.
During the 1980s and for much of the 1990s, Noar Hill supported the largest known colony of Duke of Burgundy in Britain. It still supports one of the strongest. Admittedly, management between 1981 and the early 1990s favoured this species, with a third or quarter of the grassland area being grazed during the autumn and winter period, on rotation. With hindsight, this regime may well have exacerbated the pace of scrub invasion, though that was tempered by clearance work, and the grazing regime probably also allowed the Rabbit population to increase during the mid-1980s, to the temporary discomfort of the Burgundy and several other butterflies. The Rabbit population was duly reduced. Transect and other data show that the Duke of Burgundy population peaked in 1990. After 1992 the butterfly went into steady decline, associated with a reduction in Cowslip abundance under different grazing regimes. But in 2011 the Burgundy resurged wondrously on Noar Hill, largely because of ideal flight-season weather.
The Brown Hairstreak persists in the district despite having been restricted to the immediate environs of Noar Hill and Selborne Common since the late 1970s. It remains to be seen for how long such a small area can sustain a population of a butterfly which normally occurs over large tracts of land, as it formerly did in East Hampshire. However, the Brown Hairstreak has the potential to expand strongly around Selborne, given positive changes in hedge management practice in the landscape, which are now starting to happen under Environmental Stewardship. On Noar Hill, this butterfly was for a long time greatly assisted by short-rotation coppicing of Blackthorn, but recently the reserve has become less suitable for it as a result of efforts to remove encroaching scrub from the chalk pits. There have been occasional years of relative abundance, notably 1977 and 1995, but the Brown Hairstreak is, in truth, highly vulnerable in the Noar Hill district. Its survival there is an example of a butterfly's sheer tenacity.
The third of Noar Hill's special butterflies, Small Blue, was always scarce and vulnerable, apart from during the late 1970s when its foodplant, Kidney Vetch, increased spectacularly following the great drought. The butterfly seemingly died out, and was not recorded during the years 2002–2004, before reappearing in 2005. This is curious, as the nearest known colonies are more than 15 kilometres distant and there is no other site within that radius where Kidney Vetch occurs. Small Blue seems to have died out and recolonised there before, for it was not recorded between 1968 and the second brood of 1976. Extinction can, of course, be very hard to prove.
Despite great and laudable conservation effort, the long-term future of Noar Hill's butterfly fauna is by no means secure. The site is probably too small to sustain permanent populations of most of its significant butterfly species and is inexorably moving towards woodland. Indeed, the sustainability of small, intimate mosaic habitats is highly questionable. The conflicts between the grassland and scrub interests are rampant here, and many of the features listed in the SSSI citation are associated with scrub, not grassland. The challenge of halting or reversing the pace of succession here may well be, with all due respect, beyond the capacity of today's conservationists. The real challenge is to enlarge the reserve significantly, most logically by returning much of the surrounding arable land to downland, and by seeking better ecological linkage with Selborne Common. The latter is being planned.
In terms of conservation lessons, the following are apparent from forty years’ experience of Noar Hill. First, the cutting of scrub during the winter only encourages it – scrub loves being cut; once a scrub patch is cut for the first time, it c
eases to be slow-moving and becomes fast-moving. Second, grazing only controls coarse grasses, which are actually highly susceptible to it (with the exception of the unpalatable False Brome); at Noar Hill, Red Fescue takes over instead – which supports fewer butterfly species. Third, grazing does not control scrub invasion, rather it encourages it by reducing the cover of competitive grasses that hinder scrub seedling establishment. Also, modern herbicides are surprisingly ineffective against some scrub species, especially regrowth. At present, like many nature conservation sites Noar Hill is trapped within an ever-increasing spiral of frenetic conservation management. It is as if nature conservation is trying to deny change; yet conservation, like life itself, is primarily about change, and especially about how we handle change. Everything changes, if it has not already changed.
But never mind any of that, for it is all of secondary importance. Understand the genius loci, the spirit of the place, and everything else follows. Above all, Noar Hill oozes an intense sense of its spirit of place, which absorbs and transforms the visitor. It is a place of pilgrimage, and a place where experience runs deeply. Yet it is being loved to bits, by visitors and conservationists alike, and is now looking badly worn out. The spirit of place is being compromised, eroded. Noar Hill is too small to maintain its wildlife interest, or sustain current visitor pressure. It needs to break out from its confines, and expand within the landscape. There are still unique aspects of the place: vistas out and views in, hidden worlds within worlds contained within each individual chalk pit, secret places where lovers can lie, banks where poets can dream, and perhaps Cowslip bells wherein freed spirits lie; it is an intensely poetic fragment within a landscape that is now well etched upon the national poetic map. Yet, strangely, Edward Thomas never wrote about it, though he wandered through it. Perhaps he died before he could eulogise it. He was saving it, perhaps. However, the opening lines of his poem ‘Home’ say it all:
Often I had gone this way before:
But now it seemed I never could be
And never had been anywhere else;
’Twas home; one nationality
We had, I and the birds that sang,
One memory.
They welcomed me. I had come back ...
(Steep, Hampshire, April 1915)
12 The return of the wanderer
The first Hawthorn leaves were spotted on an early-leafing bush at the Chawton roundabout on the A31, in East Hampshire, on February 3rd 1983, indicating how ridiculously mild the winter had been. Providence, of course, resents being tempted, and a bitter February ensued. Heavy snow fell on the 10th and 11th, and sat there, in stolid occupation of the land, only thawing late in the month. March was kinder, even producing a minor influx of that incessant wanderer from sunnier climes, the Painted Lady, along with a scatter of immigrant Red Admirals. That month belonged to the Small Tortoiseshell, logically so as this butterfly had been numerous throughout the summer and autumn of 1982. April wobbled, badly, being the wettest on record, though it gave a scatter of good days. Once again, the first Orange-tips emerged in Hampshire on April 16th, the day the first Cuckoos arrived. Then, there was even a heavy thunderstorm at the end of the month, a precursor of things to come.
May was so wet that Common Toads bred in the tractor ruts on Noar Hill, for the first and only time. The Duke of Burgundy flight season commenced late there, on May 11th, ushered in by a windswept individual which was rapidly blown away. Over in Alice Holt Forest, by mid-May White Admiral larvae had scarcely grown following their long hibernation, and Ash trees were starkly bare. Things were so late that the Pearl-bordered Fritillary was not out in the Chiddingfold woods on the 22nd, when the first Wood Whites were emerging. Frustrated away from conducting an experimental mark-and-recapture exercise on Duke of Burgundies on Noar Hill, I was forced first to study Wall Brown larvae again, as a consolidation exercise, and then to move on to White-letter Hairstreak larvae on the undersides of Wych Elm leaves.
Spring failed, but only for summer to burst through spectacularly and produce three hot dry months, before being blasted away by gales in early September. June commenced with a bang, literally, for a series of heavy thunderstorms crossed the Channel in its earliest hours, as if to obliterate a dismal spring and usher in a most hegemonic summer. Sunday June 5th started bright, though with a sultry and distinctly ominous breeze from the south-east. I had cycled the 8 kilometres to Noar Hill, into a stiff headwind, to count Duke of Burgundies in the chalk pits, knowing that the butterfly had emerged in goodly numbers there and would that day be at peak season. I counted 229 of them in two hours before all butterflies stopped flying. From noon, individual Dukes were seen flying into the tops of low trees, which they do just before the advent of seriously wet weather. I never finished my count. Nonetheless, 229 was the highest tally I ever managed on Noar Hill. Perhaps I would have totalled around 260 had the weather not deteriorated. Had I conducted a mental risk assessment I would have abandoned the count before noon, but I didn't; instead, I carried on in the greater interests of science and passion. Thunderstorms enliven me, electrifying the mind, and I relish them. I arrived home in the midst of a cataclysmic storm that lasted until mid-evening.
On the following day, which was cloudless, several immigrant Clouded Yellows were reported from the Isle of Wight and the South Downs. Seemingly, the butterflies had flown in on the back of the storms. These reports were difficult to comprehend, for I was part of a generation of naturalists who believed that Clouded Yellow invasions were a thing of the past. The butterfly had scarcely graced our shores during the 1960s and 70s. The thinking was that agricultural intensification in central and northern France deterred them from invading the Realm of Albion. There was some justification for this view, as between 1950 and 1983 the butterfly had only shown up in anything approaching reasonable numbers in 1955 and 1969. Even the great summer of 1976 produced only a handful. But 1983 changed all that: at least 15,000 individuals were recorded that year, by perhaps a quarter of the number of butterfly recorders active today.
In Hampshire, Clouded Yellows arrived in pulses during early June. Evidence suggests that they used the major river valleys, spreading onto the adjoining downland slopes. Having dedicated that period to studying the Duke of Burgundy and overseeing the reintroduction of the Marsh Fritillary to Conford Bog, near Bordon, at the request of the National Trust, I could only receive others’ records, and wait in hope. The wait ended with a scheduled trip to the Isle of Wight on June 15th. Magic was evidently in the air, for the ferry trip over to the island was sublime, with the whaleback downs shimmering alluringly in an azure haze. There is only one way for the naturalist to cross over to the Isle of Wight – on the Lymington-to-Yarmouth ferry.
At Compton Chine we found the Glanville Fritillary numerous, seeing in the region of a couple of hundred of these hyperactive orange butterflies, skimming swiftly over the crumbling sandy cliff face and feeding greedily on the flowers of Bird's-foot Trefoil and Thrift. One particularly splendid individual fed for a while on a purple Southern Marsh-orchid spike, a memorable sight for those entranced by beauty. When a dark cloud came over they hid in grass tussocks. By Compton's Glanville Fritillary standards this was a good show, but this butterfly was comprehensively outgunned by another, for that afternoon I more than doubled my life tally of Clouded Yellows, which were arriving low over the sea in ones and twos. By the happiest of chances my dear friend Ken Willmott had also been lured over to the island: ‘It's laying eggs!’ he shrieked in delight, as a female flew in off the sea and halfway up the cliffs before commencing the all-important task of egg laying. Indeed, the females were depositing two eggs a minute on the leaves of tiny plants of Bird's-foot Trefoil and Hop Trefoil situated in pockets of bare sand, in the hottest spots. Two females were of the pale helice form, a rare colour form that occurs only in the female of the species, in which the gold is replaced by pale white. The Clouded Yellows were not alone, for a few Painted Ladies also arrived from distant shores.
A
nother batch of heavy thunderstorms hit central southern England on Midsummer eve, but these may have knocked out more Clouded Yellows than they brought in. But the influx had laid a mighty number of eggs, and had spread right the way up the country – and the weather was set fair, suggesting that there could be a sizeable emergence of home-grown Clouded Yellows later in the summer.
July dawned hot and fair, and then intensified in heat, exceeding 30 degrees Celsius for the first time since July 1976. The White-letter Hairstreak, which had had the worst of possible times following the demise of most of its elm trees during the mid-1970s, staged a most welcome comeback, having miraculously colonised the beginnings of a new generation of elms. White Admirals emerged in stunning numbers in Alice Holt Forest and elsewhere, including a couple of ‘Black Admirals’ – the rare ab. nigrina variety – followed by a mighty emergence of Silver-washed Fritillary and then Purple Emperor. The latter began to emerge in Alice Holt on the 11th, and went on to have one of its most monumental seasons. At Bookham Common in Surrey, Ken Willmott saw a string of eleven in the favoured male territory there, including a dark male of the lugenda or iole variety. This is the highest number of Purple Emperors seen in a single vista that I know of – ever. I have never exceeded seven myself, though I have managed that tally on several occasions. Ken became known as The Blessed Willmott after this veritable blessing, though no one has had the effrontery to tell him, for he is a man of impressive modesty.
I missed much of the 1983 Purple Emperor season, for NCC contracted me (ably supported by Mrs O) to survey the Carboniferous Limestone hills of the Morecambe Bay area for butterflies. Rather incredibly, they had little information on the butterfly wealth of these hills, as there were no active butterfly recorders in the region and those who travelled up from the south visited only a few well-known localities, notably Arnside Knott. I had visited the region before, having stayed with a cousin of Mother's in Grange-over-Sands in August 1967, and having visited Arnside Knott and Witherslack in 1976 and 1981, but this expedition felt like a pilgrimage into a new world, a promised land. Our journey up north took two days, in an old but intrepid Morris Minor (registration NCG 67F, Oxford blue) as we were delayed by punctures at Warwick and Preston. But the weather held, fantastically, which is what matters. For ten days we arduously searched the grey limestone hills on both sides of the Kent estuary, under sunny skies and in temperatures in the mid-twenties. Each place we visited revealed its own intense magic in its own particular way. At each, I left part of my soul behind, for such is the nature of our love for special places. Even the walled limestone massif of Whitbarrow revealed its secrets – it is a haughty place at the best of times, belonging more in the foothills of the Pyrenees than northern England, and it wishes to be treated with respect. We decided to storm it, like Joshua Son of Nun when he took the Promised Land.
In Pursuit of Butterflies Page 14