Yesterday (26th June), while surveying a site on the Downs at Storrington, I was only mildly surprised by the relative abundance of spring skippers still flying, bearing in mind how late this season is still running. I even saw Green Hairstreaks, although they weren't very green. What did surprise me was this feisty old Duke who, despite visibly falling to pieces, was attacking every one of the freshly emerged Large Skippers that crossed his territory. This butterfly wins my 'Duke of Burgundy of the Year Award'.
What did surprise me, particularly so late in the day, was this geriatric male Duke, still taking on anything that crossed its airspace. The same individual was photographed a week ago, already looking bleached and well past its sell-by date. I'm pretty sure this is the same male I first saw eleven days prior to that, making it at least 2.5 weeks old. Good effort!
Although most Duke populations in Sussex peaked a week or more ago, the later sites on cool NW facing slopes are still producing freshly hatched females. Yesterday I counted 46 Dukes over three adjacent sites, including two mating pairs and a couple of females with only very minor wear & tear. Let's hope the egging continues for another week or more.
After a disappointing count (2) at a private site, I headed to Heyshott Escarpment, where once again I was alone with the Dukes. Although I managed a healthy count of 18, including the beautiful female pictured, the numbers are now dropping off. The Duke is no longer the most common species on the slopes, overhauled by both Dingy Skipper (37) and Small Heath (46). The latter seems set for a good season. Other species included Pearl-bordered Fritillary (1), Green Hairstreak (3) and Grizzled Skipper (3). If you haven't had your fill of Dukes yet, get out there this weekend.
The chances of natural recolonisation were deemed extremely slim, though there is a small colony, the last in the south Chilterns, along a railway line over 2km away. This is isolated from a developing matrix of chalk grassland habitat patches in the Bradenham valley by intensive agriculture. The butterfly has declined drastically in the Chilterns during the last 20 years.
In late May 2010 91 eggs were harvested from the Ivinghoe Hills (NT) further north in the Chilterns. These were bred through in captivity by Ched George of BC Upper Thames Branch. From these, 29 adults were released at Small Dean Bank and 25 at Park Wood in the spring of 2011.
Close monitoring, mainly by Ched, revealed a reasonable colony at Small Dean Bank in 2012. The peak count there was 14 (3 females, 11 males) but only a maximum of 2 was recorded at Park Wood.
On Mon May 27th this year, in windy weather which hinders this butterfly considerably, 3 males and 1 egg-laying female were counted at Small Dean and a max of 4 males and 1 female at Park Wood. We undoubtedly under-recorded due to the windy conditions, and would probably have seen twice as many had we visited in calm sunny weather. At least three of the adults seen were freshly emerged, and it is likely that a few more adults are due to emerge. Habitat conditions have improved further. Hopefully enough eggs will be laid during this poor spring to see the butterfly through into next year.
Gaining official approval necessitated 4500 words of reports and letters, plus some emails and phone calls. Both donor and receptor sites are SSSIs, so double approval had to be obtained from Natural England. Internally, all wildlife releases and extirpations have to be approved by the NT's Natural Environment Panel. This required me to write a 1500 word report and attend a Panel meeting. The Panel approved the release but expressed some concern as to the long term future of the butterfly in the Chilterns under a climate change scenario - the Chilterns may become too drought-prone for a butterfly whose larvae depend on Primula leaves that remain green well into the summer. The Panel was, though, impressed by the Trust's vision for recreating chalk grassland in the Bradenham Valley (where several areas are being restored to downland from agriculture or forestry). Hopefully the butterfly will 'take' properly at Small Dean and Park Wood, and then spread to other places within the Bradenham Valley. The butterfly needs some decent weather though, and cannot have laid many eggs yet this season....
I then visited an adjacent site I had been told about to check it for dukes. At first it did not seem very appealing with waste height nettles which caused some grief but I persevered and eventually found good numbers including a mating pair - this was a new site for me so very pleasing.
This site is 'open access land' and there seems to be some scrub clearance but little grazing. The Dukes were spread along several hundred meters of the lower part of the hill so potentially great site with some careful management but I dont know who is responsible fir managing it?
I then ventured to Beacon hill in th Meon Valley again to search for Dukes but with only one tentative siting it was a bit disappointing but again very good numbers of GH.
Then across the valley to Old Winchester Hill very few butterflies around but managed to locate the small colony of Dukes spotting five in total including two females.
There was just time to finish in my favourite spot in Rake Bottom where again saw a few Dukes settling in for the evening - fantastic day seeing Dukes at three different sites Mark
The last two days (25th & 26th May) have been pretty typical for me at this time of the year, involving a mad dash to try and survey all of the Sussex Duke of Burgundy sites as thoroughly as possible. Although numbers will take another season to recover, there does at least seem to be a viable population remaining in the areas I've visited so far; sometimes only just. That's quite a relief after last year's weather, but I do have doubts that the national tally will remain unaffected by the 2012 washout. I recorded 55 Dukes over 6 different sites and on some of these the butterfly is still emerging. Along the way I'm seeing reasonable numbers of Dingy Skipper and Green Hairstreak, although the Grizzled Skipper isn't faring quite so well. While searching an area of Rewell Wood today I saw 7 or 8 Drab Looper moths, so they seem to have weathered the storm quite well. These frail looking insects are a lot tougher than we give them credit for.
On the walk itself we saw 20 - 30 Duke of Burgundy without straying from the footpaths. I later returned to scour the site and counted 42, including 3 females. I estimate they are still a week to ten days from peak here.
Perhaps the biggest surprise was the discovery that Pearl-bordered Fritillary has moved onto the site. I was gobsmacked to see a male during the walk, and even more surprised to later watch a female PBF make her first, unsteady flight. They used to occur along the Downs here in the C21st, so this might signal a welcome return. It's 11.5 Km to Rewell Wood, where the species thrives, so I suspect they've been hiding out in Charlton Forest, just over the ridge from Heyshott.
However the story was different at Rake Bottom where I came across at least sixteen individuals with at least a couple of females. This is much more like the numbers I would expect to see in early may - hopefully they have caught up.
There seems to be two colonies here the largest in pristine habitat and the other smaller one in an area heavily grazed by rabbits, having seen some of the areas available at Ramsdean it is a bit perplexing why they haven't been occupied yet.
I particularly want the piece to cover the love life of this little butterfly (he doesn't even ask her name, let alone speak to her father, propose on bended knee and get the banns read out in church. In fact, no one would want their daughter to associate with a bloke with the morals of a male Duke of Burgundy).
Unfortunately the jet stream has jumped south, ushering in foul and abusive weather. My guess is that about a quarter, or at most a third, of the 2013 adult emergence has come out so far, but the worry is that the remainder, the bulk, may not be able to hold back from emerging indefinitely: they will quickly perish if they fail to hold back and are forced emerge during a sunny hour in a wet week.
Very worrying, and not simply because I'm supposed to be helping BBC NHU to film His Grace as part of a Springwatch special on British butterflies & moths...
Yesterday (11th May) I met up with Charlie Elder, author of 'While Flocks Last' (2009), an account of his quest to see all of Britain's endangered (Red List) birds. Charlie had travelled up from Devon, specifically to see the Duke of Burgundy, despite a highly dodgy weather forecast. When I set off from Worthing it was still raining, but by the time I approached Heyshott Escarpment via the familiar country lanes, the sun had appeared and it seemed a little less windy than of late. We spend a very enjoyable few hours on the slopes chatting about butterflies, and specifically the problems facing the Duke. It will come as no surprise to learn that this species will make an appearance in Charlie's next book. It sounds like a very interesting project, but I shall say no more than that. His first effort got excellent reviews.
We had only seen an Orange Tip and Green-veined White on the way up to the reserve, but soon after 11.30 am the first Duke appeared. Closer examination showed this to be my first Duchess of the year, with a fat abdomen bulging with as-yet-unfertilised eggs. We soon started to find more, including a second female. One pair of males provided my first clash of the season, but they didn't ascend to any great height given the gusty conditions. It was over all too quickly as the clouds rolled in, but I think Charlie returned to Devon with a smile on his face.
I then headed off to Heyshott Escarpment where the emergence is well underway. The wind was now very strong and increasing, conditions which the Duke of Burgundy hates. Despite this I managed to locate 4 very fresh males, all showing that lovely blue lustre which typifies a newly minted Duke. These were the only butterflies brave enough to be out on the slopes. Sadly we are due for more of the same weather over the next few days, and that's likely to keep their heads down.
Masses of other butterfly activity though, but mainly restricted to this same small, sheltered, area in which the Duke colony is centred. As well as the usual common spring species I saw a Speckled Wood, about 8 or 9 Dingy Skippers and, if I said I had 40 sightings of Green Hairstreaks, I think that would be a gross UNDER-estimate!! Looks like they're going to have a great season!
I have an accurate set of records of His Grace's appearance at the main Rodborough site (Manor Spur) since 1993 (earliest and latest dates are in italics):
I have a much longer data set for the start of the flight season at Noar Hill, Selborne, running back to the long hot summer of 1976. That data really does show that the butterfly's season there is getting earlier and earlier. Of course, what I don't have is such good information on the last sightings of the year...
However it would seem that the earliest site in Hampshire is normally Noar Hill. So having seen a solitary Grizzled Skipper at Butser on Sunday and seeing the weather forecast for the first few days of the week were good I pencilled in a trip to Noar Hill on Wednesday.
As I travelled up theA3 the Hampshire Hangers looked like it was still winter with virtually no leaves on the beech trees whatsoever. However it was warm and sunny which was a bonus.
As I worked my way through the ancient pits at Noar Hill it was very warm in the sheltered micro climates of each bowl and reinforced why this is such a diverse site for flora and fauna. It always makes me smile when I visit Noar Hill to think that it is a man made site formed as a result of medieval chalk digging - imagine the furore such a proposal would cause now!
Butterflies were out and about in force and numbers of peacock, brimstone and orange tip were noted when I caught my first, if brief, sight of a Duke as it disappeared over the rim of one of the pits - result!
This focused my searching and shortly after I located another individual in an adjecent pit which appeared freshly emerged and still rather weak in flight. It gave a good photo opportunity but I then left it in peace to conserve its energy for the battles with other males which would inevitably lay ahead over the coming days.
I have earmarked a number of areas to explore over the weekend - some I know and some are new to me - one or two are just 'prospects' with no form known to me. With the weather looking good hopefully the outcome will be positive.
In line with most of our species, the Duke of Burgundy had a difficult time in 2012, courtesy of the Great British weather. In the last couple of issues it has been very satisfying to publish bar charts demonstrating year-on-year increases in the Sussex population of this nationally threatened species. We hope to do this again in the years ahead, but this season was all about damage limitation. Thankfully, all remaining ‘Duke’ sites in Sussex are under active management and in good condition, a situation which will soften the impact of the extremes in weather experienced this year. Despite the significant drop in the number of butterflies recorded on most sites, abundance figures remain higher than for many years prior to 2010 (total 2012 count = 360).
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The stunning Duke of Burgundy - courtesy of Iain H Leach.