Butterfly Report for 2018

Butterfly Conservation Dorset Branch Newsletter No 92 Dorset Butterfly Report for 2018 www.dorsetbutterflies.com Contents Introduction

Introduction ...... 3 utterfly Reports, even on a relatively small scale like Dorset’s, Weather ...... 4 are the result of a huge amount of work by many people. All Butterfly Data ...... 6 B First and foremost is the recording work done by hundreds of Butterfly Transect Data ...... 8 people in various ways. Our top website recorder sent in sightings Winning Species in 2018 ...... 13 of 7,045 butterflies last year, while our transect walks counted Losing Species in 2018 ...... 20 121,000. Without this huge volunteer effort we would not have the Chalkhill Blue...... 25 data which allows us to learn about what helps or hinders butterflies Rare Species in Dorset ...... 26 and which informs our attempts to help them. We hugely appreciate all your efforts. Unusual Visitors ...... 28 Butterfly Releases ...... 30 Once submitted, the reports have to be verified so, as far as possible, Who’s Who ...... 31 erroneous sightings are rejected: thanks to Nick Urch, Stephen Brown and Dom Greves for this, and to Martin Raper, who harvests the butterfly data from some national recording schemes such as Editor’s Notes iRecord and Living Records.

I apologise wholeheartedly for the lateness of this report: too much All the verified data is then amalgamated into one database by Robin to do and too little time (and energy!) George, who also enables it to be output in a mapped format, which Bill Shreeves and Robin George have done their usual wonderful job is invaluable. Thanks, Robin! in pulling together all the data and analysing it, and we hope you find this description of the 2018 butterfly year interesting. Bill Shreeves and Robin then work on analysing the data, which feeds We always need more help, in recording butterflies, conservation into the four area meetings and work and all the administrative tasks that make the Dorset Branch into this report. of Butterfly Conservation such a successful branch. If you feel you can offer us even a little time, please contact our Chair, Nigel Spring A lot of work, but hopefully it will aid our efforts both locally and nationally to help butterflies and Lyn Pullen moths, so thank you! Photo on front cover: Red Admirals by Lyn Pullen Photo on back cover: Wall by Andrew Reekie Green Hairstreak. Photo: Chris Becker 2 3 Contents Introduction

Temperature above/below 39-year average in degrees C Winter Weather from October 2017 to March 2018 Ÿ Warning! There was no maximum temperature recorded for 2 1.6 1.4 1.5 1.5 October/November. Average 5-year figures 2012 to 2016 were 1 0.7 substituted. 0.2 Ÿ 0.5 0 Rainfall was 158 mm above annual averages. This compares with 0 131 mm below average for 2017. -0.5 -0.2 Ÿ Recent evidence suggests that warmer than average winters are -1 -0.5 -0.9 not good for most species of butterflies so last winter may have -1.5 Winter Feb Mar Apr May Jun Jul Aug Sep helped. 2017/18 February Weather 2018 Rainfall above/below 39-year average Ÿ Both temperature and sunshine were well below average. This 200 contrasts with Feb 2017 where temperature was above average. 158 Ÿ 150 Rainfall was 74.1 mm above average: Feb 2017 was also above 100 74.1 77 average. Ÿ Not a butterfly friendly month, but the lower than average 50 22.8 temperatures may have been favourable. 0 -50 -35.5 -45 March Weather 2018 -100 -56.6 -84.6 Ÿ Sunshine well below average but mean temperature was average. -150 -114.40 Ÿ Rainfall 77mm above average. Winter Feb Mar Apr May Jun Jul Aug Sep 2017/18 Ÿ Probably not the sort of month which could have launched a good season for caterpillars out of hibernation. Average sunshine above/below 23-year average 2.5 Summer Weather: April to September 2018 1.9 Ÿ 2 1.5 1.6 1.5 Temperature above average from April to July. August at average. 1.5 1 Ÿ Sunshine above average from April to September. 1 0.4 Ÿ 0.5 Rainfall below average from May to September. 0 Ÿ Easily the best summer weather since 2013 and even then the -0.5 -0.3 -0.4 rainfall was above average. -1 Ÿ -1.5 As the summer moved on it is likely that caterpillar foodplants -2 -1.6 and butterfly nectar plants suffered from the lack of rain. Winter Feb Mar Apr May Jun Jul Aug Sep 2017/18 However, some species like Brown Argus, Wall and Speckled Wood seem to have had a partial third brood despite this. 4 5 Weather Weather

Sources of buerﬂy records 2018 showed a 7.7% increase Bars show 2018 and 2017 Figures on the chart are for 2018 2018 - 252,841butteries 150,000 130,567

2017 - 234,802 butteries 100,000 44,189 50,000 22,195 20,637 12,005 9,510 e receive butterfly Records 7,512 6,226 records from www.gardenbutterflysurvey.org - Wmultiple sources. and ‘Wider Countryside’ The most scientifically reliable sightings. figures for increases and decreases in species numbers Add in a few other bits and 2018 2017 are our ‘transect’ walks, because pieces, and there are a huge number of records, all of which they are walked under set Meadow Brown in the ‘Counting Dorset’s Butterflies are verified as far as possible by conditions. To these are added countryside in July would be and Moths’ which has lots of a small team of dedicated the records reported via our nodded through, but a sighting of useful information, plus the rules people, to whom we give website and other sources, a Purple Emperor in Poole for the formal transect walks. grateful thanks. A sighting of a which cover the entire year would be looked into very Available free to those serious rather than the set 26 week thoroughly. about butterfly recording in period of transect walking. Dorset: contact Lyn Pullen (see The wide range of ways you can inside back cover) or there is a Two national online systems approach recording butterflies is link to an online version on the used for recording all sorts of detailed on our website. Recording page of the website. wildlife are iRecord and There is also a booklet: LivingRecord, and these (eventually) feed local records back to us. Although our name is “Butterfly Conservation” (for simplicity), we do work just as hard to help moths. If you record moths, Three schemes run nationally by there is a lot of helpful information on the website of our Butterfly Conservation HQ also sister organisation, the Dorset Moth Group: bring us records: the Big www.dorsetmothgroup.info. Butterfly Count, Garden A Purple Emperor insisting on being To report your moths, use www.livingrecord.net recorded! Photo: Mark Pike 6 7 All Butterfly Data for 2018 All Butterfly Data for 2018

Sources of buerﬂy records 2018 showed a 7.7% increase Bars show 2018 and 2017 Figures on the chart are for 2018 2018 - 252,841butteries 150,000 130,567

2017 - 234,802 butteries 100,000 44,189 50,000 22,195 20,637 12,005 9,510 e receive butterfly Records 7,512 6,226 records from www.gardenbutterflysurvey.org - Wmultiple sources. and ‘Wider Countryside’ The most scientifically reliable sightings. figures for increases and decreases in species numbers Add in a few other bits and 2018 2017 are our ‘transect’ walks, because pieces, and there are a huge number of records, all of which they are walked under set Meadow Brown in the ‘Counting Dorset’s Butterflies are verified as far as possible by conditions. To these are added countryside in July would be and Moths’ which has lots of a small team of dedicated the records reported via our nodded through, but a sighting of useful information, plus the rules people, to whom we give website and other sources, a Purple Emperor in Poole for the formal transect walks. grateful thanks. A sighting of a which cover the entire year would be looked into very Available free to those serious rather than the set 26 week thoroughly. about butterfly recording in period of transect walking. Dorset: contact Lyn Pullen (see The wide range of ways you can inside back cover) or there is a Two national online systems approach recording butterflies is link to an online version on the used for recording all sorts of detailed on our website. Recording page of the website. wildlife are iRecord and There is also a booklet: LivingRecord, and these (eventually) feed local records back to us. Although our name is “Butterfly Conservation” (for simplicity), we do work just as hard to help moths. If you record moths, Three schemes run nationally by there is a lot of helpful information on the website of our Butterfly Conservation HQ also sister organisation, the Dorset Moth Group: bring us records: the Big www.dorsetmothgroup.info. Butterfly Count, Garden A Purple Emperor insisting on being To report your moths, use www.livingrecord.net recorded! Photo: Mark Pike 6 7 Butterfly Transect Data 2018 Butterfly Transect Data 2018

Highest number of species seen: 34 at Fontmell Down 32 at Alners Gorse 32 at Bindon Hill 32 at Cerne Giant

ransect walks are always more help is always needed to our biggest contributor ensure all 26 weeks are walked. Tof records, and the most If you would like to become part scientifically useful, in that they of a transect walking team, have a set of rules regarding the please contact Bill Shreeves (see Compton Down. Photo: Bill Shreeves conditions in which to walk, inside back cover). There is a which makes the data more map showing the location of the Although all transect teams try paid at the national living wage accurately comparable over a walks on our website - go to to make sure all 26 weeks are of £8.21 per hour, that would long period of time. ‘Recording’, then ‘Become a walked, some inevitably are cost £18,900. Feel proud of Recorder’ and scroll down to missed, often due to the yourselves! Dorset runs a high number of ‘Butterfly transect and target weather not being sufficiently transect walks - 64 in 2018 - and species recording’. good. 64 walks, walked 26 times The number of walks missed gives a potential total of 1,664 gives us some sort of indication individual walks. 2017 was an of how good a butterfly year it Number of missed walks 2006-2018 excellent year, with only 124 was, so 2018 looks like it should 300 282 268 276 missed, and 2018 was not far be quite good. 261 255 236 240 behind with only 129 missed, or 250 225 212 7.5% of the total. Regarding the actual butterfly 195 200 174 records, the computer software Our very grateful thanks to all we use: ‘Transect Walker Online’ 150 129 124 the dedicated walkers who uses an averaging system to 100 turned out to do the counts. If create records for missed walks, the average walk takes 1.5 hours but generally missed walks still 50 (probably an underestimate), you count quite heavily against 0 spent (1535 walks x 1.5 hours) results. 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2,302 hours walking. If you were

8 9 Butterﬂy Transect Data 2018 Butterﬂy Transect Data 2018

Highest number of species seen: 34 at Fontmell Down 32 at Alners Gorse 32 at Bindon Hill 32 at Cerne Giant ransect walks are always more help is always needed to our biggest contributor ensure all 26 weeks are walked. Tof records, and the most If you would like to become part scientifically useful, in that they of a transect walking team, have a set of rules regarding the please contact Bill Shreeves (see Compton Down. Photo: Bill Shreeves conditions in which to walk, inside back cover). There is a which makes the data more map showing the location of the Although all transect teams try paid at the national living wage accurately comparable over a walks on our website - go to to make sure all 26 weeks are of £8.21 per hour, that would long period of time. ‘Recording’, then ‘Become a walked, some inevitably are cost £18,900. Feel proud of Recorder’ and scroll down to missed, often due to the yourselves! Dorset runs a high number of ‘Butterfly transect and target weather not being sufficiently transect walks - 64 in 2018 - and species recording’. good. 64 walks, walked 26 times The number of walks missed gives a potential total of 1,664 gives us some sort of indication individual walks. 2017 was an of how good a butterfly year it Number of missed walks 2006-2018 excellent year, with only 124 was, so 2018 looks like it should 300 282 268 276 missed, and 2018 was not far be quite good. 261 255 236 240 behind with only 129 missed, or 250 225 212 7.5% of the total. Regarding the actual butterfly 195 200 174 records, the computer software Our very grateful thanks to all we use: ‘Transect Walker Online’ 150 129 124 the dedicated walkers who uses an averaging system to 100 turned out to do the counts. If create records for missed walks, the average walk takes 1.5 hours but generally missed walks still 50 (probably an underestimate), you count quite heavily against 0 spent (1535 walks x 1.5 hours) results. 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2,302 hours walking. If you were

8 9 Butterﬂy Transect Data 2018 Butterﬂy Transect Data 2018

Number of species on all Dorset walks with Highest butterfly count on any over 50% changes above or below average 30 transect walk: 25 24 24 5850 at Durlston East 22 22 23 20 19 15 16 15 13 12 12 11 10 11 11 11 he question everybody questions about the abundance 10 8 8 asks is “Was it a good of each butterfly species, not 5 5 5 6 year for butterflies?”. The their range, so we will be using 5 4 3 T 2 1 answer has to start with “Define abundance to attempt an answer 0 what you mean by good”. The to the question. 2006 07 08 09 10 11 12 13 14 15 16 17 18 most butterflies? The most Over 50% up Over 50% Down species? The species which has The graph below gives us an increased most? The species overview of the butterflies which has spread most widely? counted on all transect walks as good as 2017, but a lot better 2006). Over the 13-year time since 2006, so you can see that than 2016. It has the fifth highest span, 2018 was the fifth highest Transect walk data answers 2018 was a reasonable year: not total over this period and its for ‘ups’ and third lowest for 121,431 compares to an average ‘downs’, so we again have a of 110,775. The number of walks suggestion that it was not a bad Total annual counts of buerflies on all Dorset we are able to cover varies a year. transect walks little from year to year, so when 160,000 133,918 we look at the total divided by Another possible measure is 140,000 130,021 128,115 127,827 the number of walks manned whether species have appeared 110,249 108,226 121,431 120,000 111,026 each year, 2018 become the sixth on a site or disappeared from it 88,698 100,719 93,683 98,372 100,000 87,795 highest. compared to the previous year. 80,000 As the graph overleaf shows, 60,000 The graph above starts us off by there were more species up 40,000 looking at the number of species from zero and fewer species 20,000 which significantly changed in down, so that gives us another 0 abundance (i.e. were 50% up or indication of a good year. 2006 07 08 09 10 11 12 13 14 15 16 17 18 down on their average since 10 11 Butterfly Transect Data 2018 Butterfly Transect Data 2018

Number of species up from or down to zero from the previous year 250 215 210 197 192 185 2018 The 200 137 153 125 151 136 144 131 144 150 124 131 134 Top Purple 114 110 102 106 109 100 91 87 86 Species Hairstreak 74 68 50

0 here were 10 “winners” count, spending much of its time 2006 07 08 09 10 11 12 13 14 15 16 17 18 in 2018, but the Purple up in the top of oak trees, Up from 0 Down to 0 THairstreak is the only seeking honeydew secreted by butterfly to have increased aphids. It is probably that the The graph above is another way walks in year one, but only seven compared to both its annual very hot summer weather of making a judgement as to walks in year two, that would average figure and to its previous reduced the aphids and whether it was a good butterfly count as three walks going down year’s figure. therefore the honeydew, forcing year: how many species which to zero. Then if Purple the butterflies down to find were not recorded on a Hairstreaks were seen on 20 There were 101 reports of this alternative food at a level where particular transect last year walks in year one, but only on butterfly in 2018, which is the they could be more easily were seen this, or how many three walks in year two, that second-highest figure since 1999: counted. species seen the previous year would add another 17 walks only 2004 beats it, with 117. The on a particular transect were which are down to zero. So then number of walks where it was Ex-Dorset member Lawrie de not seen this year. the total would be 20, and so on. counted was not very high Whalley counted over 50 on a There are limitations to this however, only 8 compared to a visit to a wood in Surrey, so it is You can get the overall idea methodology, so it is only meant record 15 in 2005. See the not just a Dorset phenomenon. from looking at the figures. If as an indicator. previous page for related graphs. you want to understand how the Highest counts were 47 at figure is derived, you need to As the graph shows, more Even this record number is still a Lydlinch, 19 at Piddles Wood and grasp that it is a combination of figures were up from zero than low figure, but is unlikely to be a 10 at Alners Gorse. species and walks. So if down to zero, suggesting that it true reflection of its abundance, Brimstones were seen on 10 was not a bad year. as it is a very difficult butterfly to

12 13 Butterﬂy Transect Data 2018 Top species in 2018

12 13 Other Winning species in 2018 Other Winning species in 2018

he nine other winners in 2018, which achieved either 50% Brown Argus above their annual average or above the previous year, but 61% of sites gained over 50% compared to their annual Tnot both were: averages. This is the seventh time since 2000 the Brown Argus has been a winner, and the second highest count since 2000. Ÿ Ÿ Essex Skipper Large White 202 were counted at Ballard Down. Ÿ Brown Argus Ÿ Green-veined White Ÿ Ÿ Brown Argus on all Dorset Walks Silver-studded Blue Common Blue 1200 1008 1000 Ÿ Silver-washed Fritillary Ÿ Small Heath 854 861 800 682 676 628 615 Ÿ 567 579 Small White 600 535 457 441 445 409 400 321 338 261 172 Essex Skipper patchy black, the butterﬂy is not 200 141

It can be difﬁcult to tell an Essex an Essex. 0 Skipper apart from a Small The advice is that if in doubt you Skipper when doing a transect record it as a Small Skipper. Brown Argus. Photo: Brian Arnold. walk, given the rules say you Despite this, 67% of the walk sites should maintain a steady walking reported numbers more than To tell a Brown Argus apart from a Common Blue look at the pace, which does not give you 50% above their annual average. underside of the forewing - the former has no spot closer than time to stop and examine the halfway in to the body. antennae tips. If it is an Essex, it The highest count was 13 at must show clear cut-off of the Bindon Hill (Lulworth), with Common Blue 60% of sites gained over 50% on black tips to its antennae which Fontmell Down in North Dorset 2017, and it scored its third are visible from the underside being a close runner-up with 12. highest count since 2000. too; if they are greyish, brown or The total of 8,612 was beaten in

Essex Skippers on all Dorset Walks 2003 (9,124) and 2010 (10,636) 140 116 116 120 100 Common Blue on all Dorset walks 100 90 90 84 82 12,000 10,636 80 9,124 8,612 10,000 7,149 59 57 58 60 47 51 50 6,074 41 8,000 5974 5,799 4,863 40 29 5,264 4,454 5,463 23 24 6,000 4,799 4,193 16 4,535 4,232 20 6 3,586 4,000 0 2,128 2,104 2,174 2,000 Mating pair of Common Blues. 0 Essex Skipper. Photo: Mark Pike Photo: Shona Refoy 14 15 Other Winning species in 2018 Other Winning species in 2018 he nine other winners in 2018, which achieved either 50% Brown Argus above their annual average or above the previous year, but 61% of sites gained over 50% compared to their annual Tnot both were: averages. This is the seventh time since 2000 the Brown Argus has been a winner, and the second highest count since 2000. Ÿ Ÿ Essex Skipper Large White 202 were counted at Ballard Down. Ÿ Brown Argus Ÿ Green-veined White Ÿ Ÿ Brown Argus on all Dorset Walks Silver-studded Blue Common Blue 1200 1008 1000 Ÿ Silver-washed Fritillary Ÿ Small Heath 854 861 800 682 676 628 615 Ÿ 567 579 Small White 600 535 457 441 445 409 400 321 338 261 172 Essex Skipper patchy black, the butterﬂy is not 200 141

gained more than 50% on annual Silver-studded Blue Silver-washed Fritillary Best counts were mainly from east and south Dorset. 60% of sites This eye-catching woodland average. The best site was gained over 50% on annual averages and 2018 saw a record total butterﬂy had its ﬁfth highest Stubhampton Bottom with 287. count of 1,640; next best was 2013 with 1,167. count since 1999. 52% of sites This species seems to be doing Silver-washed Frillary total 3500 on all Dorset walks well in Dorset based on its 905 were counted at Sopley 2880 3000 distribution, which was found in Common. 2500 1611 1651 2000 1454 241 kilometre squares in the 1645 1354 1526 1183 1500 1314 775 1182 1008 1049 1995-99 recording cycle, but 449 Silver-studded Blue on all Dorset 1000 779 588 846 733 540 607 488 2000 Walks 500 in the 2010-14 time span: an 1,640 0 1500 increase of 86%. 1,167

1000 882 894 883872 760 682 684 674 749 584 593 610 435452 484 500 252283

Silver-studded Blue. Photo: John Woodruﬀ Silver-studded Blue on birds-foot trefoil food plant on Portland the island suffered badly in the Considering how well the Silver- dry weather. Studded Blue did elsewhere, the results on Portland were It has been clear for some time disappointing. There were none that Portland does not move in at Perryﬁelds, and numbers were harmony with the heathland well down at both Broadcroft sites. Heath sites in the east all and Tout. It could be that the did well, though in the south Studland and Hethfelton (near Total Portland count of Wareham) did not share in the 1400 Silver-studded Blues 1,167 1200 bonanza, but at least remained 1000 894 800 relatively stable. There was some 600 484 consolation for Portland in that 400 291244 200 94 98 109 128 109 their sites’ combined count was 45 33 57 28 24 41 55 34 0 lower in 2015 and 2009. Silver-washed Fritillary sharing a buddleia ower with a Red Admiral. Photo: Harold Gillen

16 17 Other Winning species in 2018 Other Winning species in 2018

1000 882 894 883872 760 682 684 674 749 584 593 610 435452 484 500 252283

16 17 Other Winning species in 2018 Other Winning species in 2018

Three of the Whites did well in The three species are shown on Small Heath Small Heath on all Dorset walks 9000 8252 2018. a combined graph to save space, 8000 7070 6504 7140 5005 5914 7000 5988 5969 but the comparison between 52% of sites gained by more 6000 5000 3655 3683 3825 Small White. them is quite interesting. than 50% on 2017. 4000 2344 3640 3000 1979 2732 2033 2618 Third highest count since 2000. 2000 1495 1403 1000 78% of sites over 50% up on It was only the seventh highest 0 2017. count since 2000, but it made a big recovery from a low of 3640 The Small Heath never has its Large White in 2017, which was itself a good wings open when it lands, which Third highest count since 2000. recovery on the year before, helps with its identification, but 56% of sites gained by more than when we only counted 2,618. It makes finding a photo of the 50% on 2017. can be seen from the graph that uppersides next to impossible: if it does have high fluctuations Green-veined White you have one, please send it in from year to year. Fourth highest count since 2000. to us; pinned specimens not 56% of sites up more than 50% allowed! on 2017. Green-veined White. Photo: Mel Bray.

Large, Small and Green-veined White on all Dorset walks 12,000 Green-veined White Large White 10,000 Small White

8,000

6,000

4,000

2,000

0 2000 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 2018 Small Heaths. Photo: Shona Refoy 18 19 Other Winning species in 2018 Other Winning species in 2018

Large, Small and Green-veined White on all Dorset walks 12,000 Green-veined White Large White 10,000 Small White

8,000

6,000

4,000

2,000

0 2000 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 2018 Small Heaths. Photo: Shona Refoy 18 19 Losing species in 2018 Losing species in 2018

he following species are losers because numbers recorded are both less than 50% of the 2017 ﬁgure and less than 50% Tof their average on more than half of the walks on which they are recorded. Six species came up as losers in 2018:

Ÿ Small Tortoiseshell Ÿ Marsh Fritillary Ÿ Wall Ÿ Red Admiral (regular migrant) Ÿ Painted Lady (variable migrant) Ÿ Clouded Yellow (variable migrant)

Small Tortoiseshell was also its fifth consecutive Small Tortoiseshell. Photo: Dave Law A butterfly which is causing us year as a losing species. some concern. As the graph One theory for the decline is warming; it also attacks the 19 casual sightings in September shows, 2018 had the lowest ever that the parasitic fly Sturmia Peacock and Red Admiral but and October. Only three were count on transect walks. This bella is prospering due to global studies suggest that the Small seen on transect walks in Tortoiseshell’s life-cycle is more September. They may have closely synchronised with that of hibernated early, but you would Small Tortoiseshell on all the fly, so it may be more prone expect to see them nectaring at 7,000 6,229 Dorset walks to parasitism. There is an some point before winter, and 6,000 excellent clip on You Tube Malcolm Hull, who monitors 3,864 showing how Sturmia bella them in his garden shed, did not 5,000 2,486 operates by detecting the see them leave at any point. 4,000 caterpillars and laying its eggs 1,540 3,000 2,408 2,459 1,750 1072 near them, so that they then If you have a suitable outhouse, 2,000 555 998 1,006 ingest the eggs which hatch please consider starting a winter 1,169 711 655 304 1,000 404 486 640 inside them transect in it, where you look for 386 hibernating butterflies, and don’t 0 Sightings of Small Tortoiseshells forget to send in any sightings. just fell away after August: only 20 21 Losing species in 2018 Losing species in 2018 he following species are losers because numbers recorded are both less than 50% of the 2017 figure and less than 50% Tof their average on more than half of the walks on which they are recorded. Six species came up as losers in 2018:

Ÿ Small Tortoiseshell Ÿ Marsh Fritillary Ÿ Wall Ÿ Red Admiral (regular migrant) Ÿ Painted Lady (variable migrant) Ÿ Clouded Yellow (variable migrant)

Marsh Fritillary Red Admiral Red Admirals on all Dorset Walks It was this butterﬂy’s ﬁfth year as a This was the worst performing 8,000 7,000 6,691 loser and the graph clearly shows species with 84% of its 64 sites 6,000 5,000 more than 50% down on 2017 4,062 it has not performed well since 4,000 1,835 3,465 1,545 1,685 3,000 1,562 2,490 and 63% of its sites over 50% 1,381 1,747 906 2011. 69% of its 18 sites were over 1,562 1,817 2,000 1,086 1,105 1,319 986 976 884 853 50% down on their annual average. down on annual averages. This 1,000 453 610 745 Lydlinch Common was the highest represented a 75% drop in 0 count in Dorset at 132. This is numbers from the previous year particularly pleasing as it has been Marsh Fritillary underside. Photo: Caroline and was the fourth lowest count the subject of careful management Stringer since 1996. Top count came from in recent years. Cerne with 280.

We do not know the reason for Marsh Frillary on all Dorset Walks this. The resident population is 2500 2,236 thought to be only a small 2,050 fraction of the number we see 1,719 2000 1,593 each year, which is increased by migrants arriving in May and June 1,535 949 Red Admiral. Photo: Shona Refoy 1500 from central Europe. Even if the 614 initial migration was poor, you The Red Admiral was reported in 462 708 1000 681 403 453 might expect them to have done every month of 2018 on the 512 358 301 421 436 417 better later, as the weather website. 500 277 appeared favourable. 0

The Dorset Branch of Butterfly Conservation is one of 32 branches of the national society, which is based near Unusual sightings of the Marsh Fritillary included one seen on 22 Lulworth. Members of Butterfly Conservation are May on the downs above Ulwell (Swanage) by Andy Martin, which is automatically members of their local branch, but can join only the fourth record in Purbeck since 1970. This is thought likely other branches as well for a small fee. to be a release. One was also seen at Bagwell Farm Touring Park Chickerell (Weymouth) in June by Karen Kennedy; there are no www.butterfly-conservation.org.uk known colonies nearby.

22 23 Losing species in 2018 Losing species in 2018

22 23 Losing species in 2018 Chalkhill Blue

Wall Walls on all Dorset walks 600 534 495 A tale of two halves. Overall, 424 532 500 52% of its 23 sites were more 316 354 400 305 251 than 50% below their annual 246 263 300 150 226 240 234 196 averages, but these poor results 200 127 166 113 83 were due to the performance of 100 the west and north regions. In 0 south Dorset it was the top butterﬂy species and the total been some encouraging signs that it is still on the chalk of Blue markers show where count on all Dorset walks was Chalkhill Blues were the third highest since 2000. north Dorset. A second brood individual was seen at Cashmoor recorded in 2018 (none are hidden by this box). This species is now almost on 5 August and there were late non-transect sightings on both Black markers show visits in exclusively found in the south of 2018 where none were seen the county. There have, however, Hod and Hambledon Hills. Painted Lady Only small numbers of this he Chalkhill Blue is a species which continues to worry us, migrant were reported in 2018: having virtually disappeared in the west of the county. a total of 141 on the transect TTheories to explain this include chemicals excreted from walks. cows, a rise in temperature, or a speciﬁc pathogen.

We have not see a major In 2018, in the west of the county, the species was only recorded on migration since 2009, when the the three Portland transects, and was yet again missing from the four transects recorded 5035, and transect walks where it used to be recorded. Numbers were up the massive invasion of 1999, from 253 in 2017 to 400. It was recorded on seven walks in other when 18,311 were counted is a parts of Dorset. very distant memory. Painted Lady. Photo: Mel Bray We have lists of sites where Chalkhill Blues were recorded in the past, and are always looking for recorders to go out and look for Clouded Yellow them again. We are keeping a database of all the results, including the It was not a good year for this migrant either: only 113 counted on visits where none were found. If you would like to get involved, walks. The last major migration was 2006, when we counted 802. please contact Bill Shreeves or Robin George (see inside back cover for contact information). 24 25 Losing species in 2018 Chalkhill Blue

Purple Emperor White-letter Hairstreak A few more sightings of this This species suffered when Dutch Elm disease reduced the numbers species are coming in than we of this tree in the UK significantly. Its numbers in Dorset are low, but used to receive: we had 19 it is also probably under-recorded, as it is not easy to spot, spending sighting from the east of the most of its time up in the tops of trees. county this year. One sighting in Alderholt and one in the same A smattering of records came into Verwood garden as in 2017 gives Purple Emperor in Garston Wood in 2018. the website, as can be seen on the us some hope that there is a Photo: Dave Law map, and we also had reports of breeding colony somewhere in one in a garden in Buckhorn concentrated effort, we did not this area, while Dave Law sent us Weston (near Gillingham) and on find any at Deadmoor Common a photo of a Purple Emperor egg the Duncliffe transect walk, both (near Sturminster Newton) laid in Garston Wood and of which are new areas for it in where there was an uncon- congratulated the RSPB for Dorset. It is doing well at our firmed report of one the providing good conditions for Alners Gorse Reserve. previous year. this species. However, despite a Wood White Another species only just remaining in Dorset. It can now only be found to the west of Lyme Regis on the undercliffs that straddle the Devon border and on The Spittles, just east of Lyme Regis. We ask that if you go looking for it, please take great care, as these areas are not always very accessible or stable. Small Pearl-bordered Fritillary This still just hangs on in Dorset, on Godlingston Heath in Purbeck. The National Trust are working to manage the area to encourage this butterfly, so we hope it will survive. This is a small and vulnerable colony, so it is preferable that you refrain from visiting as any disturbance might have a Small Pearl-bordered Fritillary. detrimental effect. Photo: Brian Arnold White-letter Hairstreak. Photo: David Parish 26 27 Rare species in Dorset Rare species in Dorset

Large Tortoiseshell Queen of Spain Fritillary One sighting, on the coast near Three were reported in 2018, all Burton Bradstock on 26 July. This in the south of the county. One is a European species, and very was north of Knitson, in Purbeck, rare migrant to the UK, mostly (20 April); one at the Warmwell seen along the south coast. It can Gravel Pits (26 April) and the be recognised by the large silver other was at Bottom Combe spangles on the underside of the hindwings, which show clearly in Quarries on Portland (1 July). Queen of Spain Fritillary 2018. Tony’s photo. Photo: Tony Hayne There are occasional sightings along the south coat from West Large Tortoiseshell at Warmwell Gravel Pits Monarch Sussex to South Devon, Two were recorded in 2018: one in 2018. Photo: Bob Ford suggesting that the spring at West Moors and one at the sightings are migrants. Portland Bird Observatory.

The Large Tortoiseshell is, as its The most likely source of these is name suggests, larger than the that they have been released, Small Tortoiseshell: 75mm as possibly by the butterﬂy being opposed to 56mm wingspan. used as live confetti at weddings: a practice we do not condone. It is duller in colour than the Monarch. Taken at the Portland Bird Small Tortoiseshell and lacks the Observatory in 2018. Photo: Roger Hewitt white spots near the tip of the Small Tortoiseshell. Photo: Brian Arnold forewings. The underwings are a lot darker. Could you leave us something in your will? Although the vast majority of the work undertaken by the branch Considered common in Victorian times, it has not been resident in is volunteer-led, there are always things which have to be paid for, the UK since the 1950s, but it remains fairly common in Europe. and we want to ensure have sufﬁcient income to continue our Sightings are probably migrants from the continent or releases, and direct conservation work at the very least. the majority are along the south coast, though there are some in the If you could leave us something in your will, it would be of south-east and a few scattered records elsewhere. immense value to us; if you want the money to come to Dorset Branch you need to specify this.

28 29 Unusual visitors Unusual visitors

28 29 Butterfly Releases Dorset Branch Who’s Who Chair & Reserves Manager Committee Member e have mentioned them go, which usually leads to Nigel Spring* Stephen Brown* butterfly ‘releases’ a them dying out within a short Sherborne. Dorchester Wcouple of times in time. The very successful 07981 776767 [email protected] this report, so what do we introduction of Large Blues in [email protected] mean? the West Country was due to Committee Member some very rigorous science by Secretary, Garden Records & Wider John East* Countryside Survey Sturminster Newton A butterfly release is when a Dr Jeremy Thomas and his team, Adrian Neil* 01258 472193 number of butterflies is let go in combined with a lot of work to Preston, Weymouth [email protected] an area where they would not prepare the habitat and to 01305 832937 Meetings usually be found. There are two manage it afterwards, which adrian.neil@madasafish.com main reasons for this. involved many people and Arthur Bryant needed a lot of money. Treasurer Shaftesbury. 01747 228252 Georgie Laing* One is the use of butterflies as Conservation Weymouth. 01305 766712 Richard Belding, Dorchester live confetti at weddings (or The practice also makes it [email protected] sometimes funerals). difficult for us to tell if unusual 01305 264868 Unfortunately, the species used butterflies turning up are Membership & Branch Liaison [email protected] Robin George* are often not native, so they are genuine or if they are Sales Stall Gillingham. 01747 824215 not going to able to breed and introductions which will appear Colin Burningham 01935 873219 [email protected] will just die out. in our figures this year but 07849 921594 probably be gone by next year. Records [email protected] Bill Shreeves* The other releases are those While we all want to see more * denotes Committee Member made by individual people butterflies around, and to get Shaftesbury. 01747 852587 thinking that they will be able to back species which are extinct in [email protected] introduce a species where it a certain area, random releases Website & Social Media Butterfly Conservation. Company limited by either has not existed before, or are not the best way forward. Lyn Pullen* guarantee, registered in England re-introduce it where it has died Winfrith Newburgh. 01305 853946 (2206468). Registered Office: Manor Yard, out. See Butterfly Conservation’s dorsetbutterfl[email protected] East Lulworth, Wareham, Dorset BH20 5QP. website for the full policy on Newsletter Charity registered in England and Wales While the motives behind this introductions: Jane Smith* (1254937) and in Scotland (SCO 39268) thinking are usually pure, there https://butterfly- Sherborne. 01935 814029 needs to be a lot more done conservation.org/our- [email protected] All material in this magazine copyright than just obtaining some work/policies-and-statements Butterfly Conservation Dorset Branch.The Committee Member opinions expressed in this newsletter are chrysalises, breeding them Richard Norman* not necessarily those of the society or the through to adults and letting Sturminster Newton. 01258 472887 Branch. [email protected] 30 Butterfly Releases Dorset Branch Who’s Who Chair & Reserves Manager Committee Member e have mentioned them go, which usually leads to Nigel Spring* Stephen Brown* butterfly ‘releases’ a them dying out within a short Sherborne. Dorchester Wcouple of times in time. The very successful 07981 776767 [email protected] this report, so what do we introduction of Large Blues in [email protected] mean? the West Country was due to Committee Member some very rigorous science by Secretary, Garden Records & Wider John East* Countryside Survey Sturminster Newton A butterfly release is when a Dr Jeremy Thomas and his team, Adrian Neil* 01258 472193 number of butterflies is let go in combined with a lot of work to Preston, Weymouth [email protected] an area where they would not prepare the habitat and to 01305 832937 Meetings usually be found. There are two manage it afterwards, which adrian.neil@madasafish.com main reasons for this. involved many people and Arthur Bryant needed a lot of money. Treasurer Shaftesbury. 01747 228252 Georgie Laing* One is the use of butterflies as Conservation Weymouth. 01305 766712 Richard Belding, Dorchester live confetti at weddings (or The practice also makes it [email protected] sometimes funerals). difficult for us to tell if unusual 01305 264868 Unfortunately, the species used butterflies turning up are Membership & Branch Liaison [email protected] Robin George* are often not native, so they are genuine or if they are Sales Stall Gillingham. 01747 824215 not going to able to breed and introductions which will appear Colin Burningham 01935 873219 [email protected] will just die out. in our figures this year but 07849 921594 probably be gone by next year. Records [email protected] Bill Shreeves* The other releases are those While we all want to see more * denotes Committee Member made by individual people butterflies around, and to get Shaftesbury. 01747 852587 thinking that they will be able to back species which are extinct in [email protected] introduce a species where it a certain area, random releases Website & Social Media Butterfly Conservation. Company limited by either has not existed before, or are not the best way forward. Lyn Pullen* guarantee, registered in England re-introduce it where it has died Winfrith Newburgh. 01305 853946 (2206468). Registered Office: Manor Yard, out. See Butterfly Conservation’s dorsetbutterfl[email protected] East Lulworth, Wareham, Dorset BH20 5QP. website for the full policy on Newsletter Charity registered in England and Wales While the motives behind this introductions: Jane Smith* (1254937) and in Scotland (SCO 39268) thinking are usually pure, there https://butterfly- Sherborne. 01935 814029 needs to be a lot more done conservation.org/our- [email protected] All material in this magazine copyright than just obtaining some work/policies-and-statements Butterfly Conservation Dorset Branch.The Committee Member opinions expressed in this newsletter are chrysalises, breeding them Richard Norman* not necessarily those of the society or the through to adults and letting Sturminster Newton. 01258 472887 Branch. [email protected] 30