Wiltshire is a stronghold of one of our less well-known butterflies – the Duke of Burgundy. It used to be known as the Duke of Burgundy Fritillary because its pretty orange and deep brown chequered markings resembled those of our other Fritillary butterflies. However, as it is actually from a different family – the metalmarks – the name has now been shortened to avoid confusion.
In the past, the Duke was primarily found in woodlands, where it fed on Primroses growing in dappled sunlight of coppice woodland. However, changes in forest management caused most woodland colonies to die out. It is largely restricted to the chalk and limestone areas of southern England, with scrub, gullies, or slopes to provide shelter, although isolated colonies are also found in the southern Lake District and North York Moors. It flies from late April into June and hereabouts colonies can be found along the northern side of the Shaston Ridge, parallel with but to the south of the A30. Here it favours the base of the slopes where the soil is deeper and moister. This, and less exposure to the sun prevents the leaves of the cowslips, on which its caterpillars feed, from drying out too quickly. The damage the caterpillars do to the leaves as they feed is very distinctive and can provide evidence of breeding even if no adults are seen. The Duke is often overlooked as it is a tiny butterfly and can be confused with skippers or small day-flying moths that may be found in the same habitat at the same time of year. They are fast-flying and rarely visit flowers. What sets the Duke apart, is the habit of the very territorial males spending much of their time on prominent perches on the edge of bushes or atop grass tussocks. From there they keep a look out for passing females which are pursued ardently. The male will also sally out aggressively to inspect any approaching insect, and if it is another male, they often do battle, spiralling rapidly upwards in a dogfight. The victor returns to their perch. If you disturb one, the males will often return to the same perch or very nearby, so you just have to be patient and wait for it to come back. These locations, sometimes called leks, seem to be favoured every year by newly emerged butterflies which identify the same locations to defend against all-comers. The females are less conspicuous, flying low over the ground, looking for suitable plants on which to lay their eggs. These flights may take them away from where they emerged, helping to establish new colonies if the right habitat can be found. An unusual feature of the Duke is that it exhibits sexual dimorphism, in that the male and the female are distinctly different. As we know, most insects have six fully functioning legs, but the male Duke only has four. by Andrew Graham Hover over the photos for captions Eight hardy souls donned boots and waterproofs, braved the dodgy weather, and explored Ansty Down on Sunday 15th May. Hoping to see the many spring butterflies that usually frequent this location, on a generally overcast and occasionally rainy morning, we were pleased to see five species. Crucially, this included the tiny Duke of Burgundy, the key butterfly we were hoping to spot. This species is on Butterfly Conservation’s list of Threatened species, so we are fortunate to have it in the vicinity.
We were joined by Dr Susan Clarke, ecologist, and expert on these (and many other) butterflies. Sue explained in detail what is known about the insect’s life cycle, what habitat it favours, how ideal site management is so difficult to determine and achieve, and how it is now more frequently seen on damp chalk hillsides than in coppice woodlands as in the past. Sue showed us how the north face of the Shaston Ridge between Burcombe and Donhead St Andrew represents the most significant location for the Duke of Burgundy in the country. This long string of interconnected unimproved grasslands provides the right habitat for a chain of colonies which, currently at least, appear to be vigorous enough to ride out good and bad breeding years. We were very fortunate that the clouds cleared, and the sun came out briefly when we were in a patch of ideal habitat. Peter immediately spotted one and soon a few others were seen nearby. These were males, perching in prominent position to sun themselves and keep an eye out for females. They allowed us to approach and get good close views of the striking brown and orange chequered markings and even to see that the male only has four legs. As well as adult butterflies we also spotted numerous Twayblade Orchids, a large Drinker Moth caterpillar and a large number of Small Tortoiseshell caterpillars feasting on a bank of nettles. Despite disappointing weather, we enjoyed a very informative walk and came away appreciative of having such an important insect colony nearby. By Andrew Graham Photos: Julia Willcock On this walk led by Andrew Graham, along with other spring downland butterflies, we will be seeking out the Duke of Burgundy, an easily overlooked species for whom Wiltshire is a southern stronghold, living in small colonies on grassland or woodland clearings, laying its eggs in small batches underneath the leaves of Primroses and Cowslips.
We will be joined by Dr Sue Clarke, an ecologist who has been advising landowners for a number or years on how to help Duke of Burgundy (on the left below) and the also rare Marsh Fritillary butterflies (on the right) to flourish. We will rendezvous at the Old Shaftesbury Drove, a Byway open to traffic, where it crosses the Ansty to Alvediston road at Grid Reference ST 965250; WhatThreeWords: ulterior.enormous.drilled. There is room for cars to park along the track on both sides of the road. For anyone wanting a lift, or to share cars, meet at the Nadder Centre car park to set out at 10:30 and rendezvous at the start point to set out at 11:00. [Please note these times are later than published in our programme, to give the best chance of sighting butterflies.] The walk will be taken at a gentle pace, but will involve some steep slopes and roughly grazed ground so supportive footwear is advised, as perhaps is a walking pole. The route planned will take 2 to 3 hours, with the aim of returning home for a late lunch. You may want to bring some refreshment, though, especially if the weather is warm. No need to book. by Dick Budden Dr. Peter Inness from the Meteorology Department of Reading University opened this fascinating talk, the last in our 2021/22 series of indoor meetings, with two images of the same patch of woodland near his Oxfordshire home taken two years apart to the day. In the first, the forest floor was carpeted with bluebells; in the second merely a green carpet with a few unopened bluebell buds visible. This was one of several illustrations he used to show how short term changes in weather can impact the natural world, as he sought to distinguish this variability from longer term trends.
In her recent PhD thesis a student at Reading had used data collected by volunteers across the British Isles (recorded on the Natures Calendar website managed by the Woodland Trust) to show that across the UK the mean first flower date for bluebells was 1st of May in 2013, but 8th April in 2017, fully three weeks earlier. Dr Inness was able to explain this difference reflected short term climate impacts, rather than long term trends. Data for bluebell first-flowering dates and temperature records for January to April in successive years show that bluebell flowering dates respond to the weather and temperature conditions during March, February and January, as the plant stems emerge and the flower buds form, rather than during the flowering period itself. And, though invertebrates react rather more rapidly than plants, similar analyses for the first appearance of orange tip butterflies and for blue tits nesting reached similar conclusions. In 2021, by contrast, hawthorn blossom appeared a whole month later than normal, reflecting an abnormally frosty April. Looking at longer term trends and the impact of climate change, however, Dr Inness referred to the paper published recently by the Royal Society. This used records on 406 plant species, some dating from as far back as the 18th century, to show a marked shift that took place in the 1980s. Plants are now emerging on average a whole month earlier each year than seventy years ago. He showed projections prepared by the Meteorological office to indicate that by 2050, in every other year we will experience summer temperatures similar to those we experienced in the very hot year of 2018. And, unless significant reductions in greenhouse gas emissions are achieved globally, these temperatures will be the annual norm by the end of the century. And he also showed projected rainfall maps clearly showing that our winters will be wetter and summers dryer, and warned that individual rainfall events will be 29% stronger. A new UK record for of 316mm rain in a 24 hour period, set as recently as 2009, was surpassed again only six years later in 2015 with a new record of 341mm. All of which suggests that nationally there are considerable tasks and costs ahead to prepare reservoirs and infrastructure to be able to cope. From a wildlife perspective these climate trends are complex and deeply concerning. Dr Inness gave as examples the likely impact on the relatively shallow root systems of beech trees, less well adapted to cope with summer drought conditions than deeper rooted oaks. And the impact on populations of birds such as swallows whose northerly migrations are triggered by seasonal changes in daylight hours. They may arrive at European destinations too late to feed their young on invertebrates maturing earlier as a result of warmer Spring conditions. Troubling as these issues are, the talk was hugely valuable and timely, providing us all with deeper insight into the impact weather and climate have on the natural world around us. by Richard Budden The following request has been submitted by Jessica Perry of the RSPB Volunteer Monitoring Farm Wildlife project.
"The RSPB Volunteer Monitoring Farm Wildlife (VMFW) project aims to provide a match up service for volunteer surveyors and farmers. The project objectives are to provide a wildlife surveying service to farms, offer opportunities for people to get out into nature and use the collected data to create useful outputs that will help farmers to adapt to nature friendly farming practices. This is currently a pilot project so many aspects are in development. The taxa surveys taking place in Wiltshire this year are pollinators, butterflies, and bumblebees. We hope to take up more taxa in future years, such as birds and plants. The surveying methods are all citizen science based, so are easy to learn and conduct, but with practice can become a valuable skill. We try to match volunteer surveyors to farms within a reasonable travelling distance. We may be able to reimburse some travel expenses. Once a match is agreed we send the surveyor the contact details to get in touch with the farmer. First there is a 'Meet & Greet' session where you agree with the farmer where and what to survey and do a risk assessment. Then surveys are conducted throughout the spring and summer. Results are submitted online by the surveyor. At the end of the year, we will turn those results into useful outputs for the farmers. It is completely up to you, which taxa to survey, although sometimes a farm might express an interest in a specific type. You can do more than one taxa if you wish and you can do more than one farm if you wish. We cannot always guarantee that a farm is nearby, however we do occasionally run training sessions and encourage our volunteers without farms to practice their skills at their local green space. The surveys differ a little in how often they are done, bumblebees can be monthly or 3 surveys throughout the surveying season (now until Oct), pollinators are monthly (now until Sept) and butterflies are fortnightly (now until Sept). Bumblebee transects are 1-2km. For butterflies you select up to 5 areas to survey and pace evenly through that area for 15 minutes recording species. For pollinator surveys the surveyor observes an area of target flowers e.g. clover, for 10 minutes, recording the pollinating insects that visit the flowers. We currently have several farms in south Wiltshire who need volunteer surveyors. There are two farms in the Tisbury area, one in the Semley area and one east of Gillingham. If anyone is interested in being involved in the project or to help us cover these farms please contact me at farmsurveys.wilts@rspb.org.uk" Mid-March into early April is the time of a “blackthorn winter”: a cold spell when the blackthorn is in bloom. This is perhaps because the combination of different strains of the species and the varied micro-climates of their growing locations mean that you can find blackthorn in flower somewhere for more than a month, during which it is likely that there will be at least one cold spell. Or perhaps it is that blackthorn scrub, with its clouds of flowers at their peak, look like the bushes have been covered with snow.
The small white flowers bloom on short stalks from buds along the spines and do so before the leaves appear. En masse, the bloom provides a welcome early source of nectar for insects. These pollinate the flowers, which then develop the distinctive blue-black sloes. The tree grows naturally in scrub, copses, and woodland, and is commonly used to form a cattle-proof hedge. It favours sunny positions, and when left uncut can develop into considerable thickets, such as those in the Oddbrook valley. Mature trees can grow to a height of around 6–7m and live for up to 100 years. The deep brown bark is smooth, and twigs form distinctive, straight, side shoots which develop into thorns. Its trunk and stems form a dense wood which is good for burning and straight stems have been used for walking sticks, including the Irish shillelagh. The foliage provides food for the caterpillars of several moths. The dense thickets provide sheltered nesting sites for birds, which then feast on these caterpillars, and later on the sloes. The scarce brown hairstreak butterfly lays its eggs on blackthorn. This is the largest and brightest of the hairstreak butterflies, the female looking a gorgeous golden colour in flight. However, in common with other hairstreaks, it is quite a small butterfly and notoriously easy to overlook. They spend most of their adult lives perched in the tops of trees, out of sight, lapping honeydew from the leaves. If you are lucky, you might see a female when she descends to lay eggs, nearly always on blackthorn twigs in hedges or bits of sheltered scrub. Our knowledge of the local distribution of this butterfly is improving all the time, due to the efforts of a small number of lepidopterists who tirelessly search suitable locations for these tiny eggs. Correctly identified, these are a reliable indicator of presence, although not necessarily breeding success, but gets around the difficulties of spotting an adult on the wing. The population appears to be spreading westwards from the area north-east of Salisbury. As eggs have been found in the vicinity of Grovely Wood, who knows, they may be present hereabouts without being recorded. Eyes peeled this August/September. by Andrew Graham Organiser: Richard Budden We couldn’t have asked for a more perfect day to visit Brownsea Island. A brilliant blue sky and calm sea set the scene for our crossing from Poole Harbour and we were met by staff from the National Trust and Dorset Wildlife Trust on the quay. After splitting into two groups – one led by Nicki Tutton, Dorset Wildlife Trust’s Wild Brownsea Project Officer and our group led by Anthony, a volunteer– we were given a tour of the northern part of the island. It took some persuasion to pull us away from the drama of nine peachicks which were responding to the throaty call of their mother. We had half of the brood on our side of the wall in the quay gardens and one by one the remaining peachicks would suddenly appear on the top of the wall and plummet down. Exotic in their own right, with a tufty brown head plume and fluffy cream and brown body feathers, they were enchanting. Although many of the volunteer projects had been delayed over the pandemic, the new oak boardwalk was now finished across a marshland patch where dense vegetation gave cover for water voles. Red squirrels were frequently seen, seemingly not too disturbed by visitors walking along nearby paths. We visited two bird hides which looked out onto the lagoon and were delighted to witness a flock of about 20 spoonbills feeding in the shallows, with avocets, black-tailed godwits and dunlin nearby. The island has a varied landscape and there’s much to explore. Meandering paths take you up small, wooded hills to pop out at stunning viewpoints over Poole Harbour to the north and the neighbouring coastlines of Arne and the Studland and Godlingston Heath National Nature Reserve to the south. Near an old redwood we saw a pale tussock moth caterpillar perilously navigating the path, identified by Nicki who said it was close to pupation. In another hide overlooking a large lake on the southern side we found a striking bug sunning itself on the window frame which we found out later was actually a Western conifer seed bug, Leptoglossus occidentalis, an American native that’s spread its reach along the south coast of Britain since 2008 and feeds on pines. It likes to come inside houses to keep warm during the winter, so watch out for these invaders later on! Organiser: Peter Shallcross Re-scheduled from 2020 When we regretfully had to cancel this visit last year, Martin Green told Peter Shallcross:- “We have just had an unprecedented number of raptors on the farm & adjacent this weekend. My neighbours cut an adjacent field for silage last week and since it has been a focal point for feeding - a few hundred corvids at least 7 red kites & 10 buzzards and a marsh harrier - not bad! My friend James Phillips visited and recorded these species around the pond and woodland planting: The highlights were Emperor dragonfly, Azure and Large Red damselfly, Small blue, Common blue, Green hairstreak, Large skipper butterflies, Burnet companion moth plus singing Lesser Whitethroat in the woodland scrub and a pair of Corn bunting and a pair of Yellowhammer on territory around the pond. Other highlights on neighbouring fields were grey partridge on territory calling, 3 pairs of Yellowhammer, a flock of 16 Corn bunting plus 4 pairs on territory, 1 pair of Linnets, 6 singing Skylark and 2 Brown hair with at least 3-4 Red kite over the nearby woodlands towards Wimborne St Giles.” So maybe it was much like that again this year. Susie Blundell sent this wonderfully atmospheric photo, adding, 'We had a lovely field trip hosted by Martin Green. I took this picture by Martin’s latest pond which he is hoping will be an attraction for Turtle Doves. Lots of wild flowers, a glorious sunset, a museum visit and a starry night - it was perfect.' Martin is a great wildlife enthusiast and he’s also a keen archaeologist, with a great deal to share. The landscape here is rich in prehistoric features – the Dorset cursus (a huge linear earthwork that runs for 10 km/6¼ miles and dates from roughly 4,000 years ago) crosses the farm. A cross-section has been excavated so you can see just what it used to look like. There’s a long barrow and several round barrows visible on the slopes, while the Roman road known as the Ackling Dyke also passes through it on its way from Badbury Rings to Old Sarum. Again, where it crosses the road nearby a cross-section has been exposed showing its construction. On top of that, excavations have found shafts that were filled-in as far back as 10,000 years ago, and the remains of ditches and enclosures dating from 4,500 to 2,800 years ago. This was the ideal opportunity to hear all about the excavations and discoveries and to visit Martin and Karen’s private museum. Organiser: Andrew Graham Hambledon Hill is the spectacular 192 metre (630 feet) high Site of Special Scientific Interest (SSSI) owned and managed by the National Trust, southwest of Iwerne Minster. The chalk grassland here is really good for wildflowers and insects, especially butterflies. The view from the summit provides a real sense of this site’s prehistoric strategic importance and why it’s considered one of the finest Iron Age hillforts in Dorset. For more on Hambledon Hill itself, go to the National Trust's pages. This is Andrew's report on the day: Twelve members spent a pleasant few hours scaling the heights of Hambledon Hill's iron age earthworks to look for butterflies and enjoy the flora. We saw a total of 17 butterfly species. A small, sheltered quarry on the side of the hill held plenty of butterflies which, because it was not very warm, were not flying much but basking on flowerheads so making them relatively easy to look at and photograph. Several Chalkhill Blues were a highlight as this species is, unfortunately, becoming less common and isn't seen in the Tisbury area. A welcome surprise sighting was a Clouded Yellow, a migrant species one or two of which are seen on Hambledon each year, but it is a matter of luck whether you bump into them. We were however disappointed not to see the Adonis Blue, but the second brood of this species doesn't seem to have emerged yet. We also enjoyed looking at the very diverse chalkland flora. In places on the steep west-facing slopes, the herbs are so prolific that hardly any grass could be seen. The Carline Thistle, with its bronzy yellow blooms which look like dried flowers, was a particular hit. The full list of flora is here, with thanks to Debbie Carter and Jill Preston. We gradually climbed the slopes of the hill, entered the fort through the banks and ditches of the entrance at the south-western end, then climbed to the neolithic long barrow on the summit. From here we could see across Wiltshire, Dorset and Somerset, and could pick out various landmarks, towns and villages. The descent back to the base of the hill was perhaps the toughest part of the walk, the steep path being particularly challenging. Mercifully, although the breeze on the top was stiff, it stayed dry and the temperature made for a very pleasant walk.
Organiser: Peter Shallcross The RSPB’s 33-hectare reserve sits in the middle of Cranbourne Chase just north of Sixpenny Handley via Ebbesbourne Wake. This ancient wood (along with coppiced hazel and maple, there are areas of oak, scrub and mixed plantation, with glades, rides and deadwood) has been managed for centuries, creating a special place for some magnificent wildlife, including blackcap and marsh tit, colourful wildflowers and small mammals like dormice. Openings in the trees create pockets of sunlight to attract butterflies, including the silver-washed fritillary (see below) and white admiral (not seen). The first excitement was butterfly orchids - a taller woodland plant (above) compared with the lesser butterfly version which is found on more open ground. There were also many common spotted orchids. Lots of different grasses, reeds etc. One of our guests proffered this helpful way of telling the difference: Sedges have edges Rushes are round Grasses are hollow Right down to the ground. So 'now you know', as she said! The blackberries were really only just coming into flowers, but once fully out (and with the impending heatwave) this will become an emporium for butterfly spotters. Something of a surprise were several different kinds of fungi: identification welcome! This being ancient woodland might explain the profusion even at this time of year. Butterflies were disappointingly in rather short supply although one silver washed fritillary (the silver wash is on the underside of the wings) was snapped Abby Eaton and others we saw were newly emerged and pristine. There were some fascinating moths, including a longhorn with, indeed, unbelievably long antennae, a surprising deposit of buff tip moth eggs and caterpillars, a large skipper butterfly all of half an inch long and a spotless ringlet (the males sometimes don't have spots). The visit ended with a peaceful picnic lunch on logs helpfully positioned in the shade, probably by RSPB volunteers. |
Photo: Avocets (Izzy Fry)
The headers display photos taken by our members. Do get in touch via the Contact Form if you'd like to submit a photo for selection.
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