David Lazarus

[David Lazarus]

Seconded. The distribution maps of this species, as well as many other common butterflies such as Orange Tips, show the location of observers and recorders, not of butterflies. If there were enough observers, I expect almost every tetrad in the county would eventually produce a Purple Hairstreak sighting. Even if every mature oak in Essex had just one adult living on it, the total population would be, and probably is, colossal.

Thanks Mark and Zayed, your comments are very welcome. The issues of under-recording and distribution maps, actually showing the location of where observers have recorded sightings rather than what we want which is to show the distribution of a butterfly species, is a running theme within my report The Butterflies of Essex. It is probably the same in every county throughout England. I have noticed though that Kent, Sussex, and Warwickshire, for instance, have managed to carry out a count in every tetrad to ascertain the distribution and abundance of particular species which I am recommending for Essex - in particular those that have gone under-recorded.

Obviously, I am not blaming anyone or any organisation. Sadly, I think it is a reflection of our UK population of 64 million plus - most do not care about the environment and/or the extinction crises we are experiencing at the moment let alone the conservation of butterflies.

According to available data, the population of Essex in 2025 is projected to be around 2.1 million people, with a continued growth trend from the current population of approximately 1.9 million. And we cannot get enough people to monitor the distribution and abundance of each of the 34 butterfly species in Essex.

As you can see, the situation is not going to get any better with the majority of the countryside in Essex used for agriculture and the need for housing development to house the projected increase of the population of 0.2 million extra people destroying more habitat and wiping out more colonies of butterflies in the process. Wow.

The problems of attempting to create a baseline for the abundance and distribution of every species found in Essex is once again highlighted next. Unfortunately, the White-letter Hairstreak is another species which is overlooked and under-recorded throughout Essex with the lack of available data shocking.

[David Lazarus]

The Butterflies of Essex
2024 Year in Review

White-letter Hairstreak Satyrium w-album

Summary
The White-letter Hairstreak is considered vulnerable to local extinction in the vice-counties of North and South Essex with the highest concern in the north-west, and is considered the highest priority when it comes to butterfly conservation. It has been described as widespread within the whole of Essex, although local and found in low density, colonies restricted to 10-25. Because of the imported Dutch Elm Disease, large numbers of all native species of Elm have been lost compounded by the destruction of miles of hedgerows within Essex. Since the 1960s, but especially during the 1980s and 90s, the White-letter Hairstreak has suffered serious decline here in Essex. National figures show both long-term and short-term trends of moderate decline in distribution and a significant decline in abundance rendering the White-letter Hairstreak categorised as Endangered in the UK. One of the problems we have here in Essex is the lack of knowledge caused by the limitations of data collection. The White-letter Hairstreak is an elusive butterfly that is rarely seen on a casual basis because of its arboreal habit. Pete notes that it is possible that the White-letter Hairstreak can go through the whole of its life-cycle in the tree tops and out of sight ***. Because it spends most of its time high up in the canopy of trees it is one of the most under-recorded of all butterflies. Rarely if ever, most butterfly enthusiasts can only see adults as a black triangular speck high up on a leaf as it does not bask with its wings open. Early in the morning and late afternoon aerial displays can be seen sometimes but you might have to wait ages and then it may not appear at all. Also, adult colonies, already small, are known to be under-estimated because most of the adults are not moving even if you know where to find them in the first place.

*** Eeles, P., 2019 Life Cycles of British & Irish Butterflies Pisces Publications

Because of the reason Mark essexbuzzard recognises in his post above, the distribution maps of the White-letter Hairstreak I have put together for you below are of limited use. I cannot form any accurate conclusions and I am afraid at best it is an informed guestimate without access to adequate or complete information. Sorry about that, but not defeated I will try the best I can.

The 2024 distribution of the White-letter Hairstreak, limited to recorded sightings on the iRecord website, provides us with some sort of clue where colonies exist but is lacking so much data that the map is of limited use and certainly does not show the actual "distribution" of the White-letter Hairstreak within Essex:

2024 Distribution of White-letter Hairstreak within Essex
Source: iRecord

And just like the Purple Hairstreak previously, the 2014-2024 records are not much better showing vast areas bereft of data, I would suggest, rather than showing an absence of White-letter Hairstreak.

2014-2024 Distribution of White-letter Hairstreak within Essex
Source: iRecord

The first recorded sighting on the iRecord website is in 2005, the first of 395 records for the vice-counties of North & South Essex. But this does not show the true monitoring of the White-letter Hairstreak. 200 of these records took place from 2010 to 2024 at one site, Benfleet Downs - and were mostly collected by one person. During the last 10 years there have been 321 records with 140 of them recorded at Benfleet Downs. In 2024 there were 56 records with a lower percentage of the total recorded sightings at Benfleet Downs - 16 records. It does not mean that Benfleet Downs is where there are most colonies of White-letter Hairstreak, but given the numbers compared to the rest of the county, it is probably the best place to go to see White-letter Hairstreak because of the GPs map references available.
What is more useful is that records seem to be more concentrated towards the south-east of Essex, and areas around Abberton Reservoir, Friday Wood & Cherry Tree Lane, and Middlewick Ranges. The Epping Forest area has less recorded sightings than I would expect. Mid-Essex has very few recorded sightings despite the amount of Wych Elm Ulmus glabra in the area, which is known to be more disease resistant than the other native elms. I also know of one colony at Maldon Wick and another at Hazeleigh Wood close by yet only 2 of us have recorded sightings there and both of those were in 2024. I think if I made a thorough search of the likely sites within Chelmsford and mid-Essex I would expect to find other colonies.

Once again, I thought I would put together a map showing the distribution map published in Corke, D., & Goodey, B., 1997 The Butterflies of Essex Lopinga Books as an overlay of the 2014-2024 map:

1990-1997 Distribution of White-Letter Hairstreak
Orange - 1990-1997 recorded sightings
Blue 2014-2024 recorded sightings

With the addition of those areas that were known to Corke & Goodey, the distribution of White-letter Hairstreak becomes a little clearer reaffirming what can be ascertained from the recorded sightings from iRecord. I still think this only gives an indication of where records have been collected by recorders visiting certain places. It does not mean that White-letter Hairstreak colonies cannot be found in hedgerows and south-facing woodland edge habitats containing elms in the rest of the county, including the previously highlighted area from central-west to the north-west of Essex where there is a lack of recorded sightings of all 34 species found in Essex.

My own records are not useful mainly because for the most part I was not looking for White-letter Hairstreak although I was looking at habitats containing elms to analyse their health - on which I was fortunate enough to find a few White-letter Hairstreak colonies and also some locations where I would expect them to be. I will target them a little more during 2025 but given the explanation above I do not expect to see many more.

2024 site locations where White-letter Hairstreak was recorded

The abundance during 2024 at these site locations are as follows:

2024 White-letter Hairstreak abundance by location

Not much can be concluded from only 16 individual butterfly sightings but at least I know where I can find them even without visiting Benfleet Downs & Belton Hills Nature Reserve adjacent to the Leigh-on-Sea railway station car park where butterfly enthusiasts tend to visit to see White-letter Hairstreak in Essex.

The 2024 abundance by date of the site visit was as follows:

2024 White-letter Hairstreak abundance by date

As you can see, most of my sightings occurred during late June with the highest number mid-July. And not surprisingly, they reflect the abundance by location because I only visited the exact location of the colony once - so we cannot draw any conclusions. Probably the most valuable conclusions for a site in Essex can be drawn from the 200 recorded sightings at Benfleet Downs over the past 14 years. Unfortunately, at the moment I do not have access to download all records from the iRecord website so I cannot analyse abundance data unless I add up the total sightings from each individual record which is not cost-effective.

South Essex

The following locations are where sightings of White-letter Hairstreak were recorded by me during 2024 within South Essex:

2024 White-Letter Hairstreak recorded sightings
South Essex site locations

Essex Wildlife Trust Maldon Wick Nature Reserve

EWT Maldon Wick Nature Reserve

The White-letter Hairstreak colony is in the 3 Wych Elms Ulmus glabra on the west side of the railway embankment, south of the bridge with forb-rich grassland slopes. Easy to find, they were remarkably active during the morning of my visit but did not nectar on the Creeping Thistle Cirsium arvense on the nearby banks unfortunately. The trees are only 6 metres high at most so even when settled good views can be had with binoculars.

EWT Maldon Wick Nature Reserve - White-letter Hairstreak were seen on a single visit on the 23rd of June. Total: 3

One Tree Hill - Northlands Wood

One Tree Hill - Northlands Wood

There is probably more than one colony of White-letter Hairstreak along the lane running along the southern edge of Northlands Wood which has a hedgerow with a high percentage of elm facing south-east and the woodland edge itself has numerous elm trees in various stages of damage due to Dutch Elm Disease. I was fortunate to observe a female ovipositing low down between 1 to 3 metres high on both sides of the lane. There was an overhanging bough where I first spotted her and went back later in the season to have a further look - it had obviously been cut off

I have created a map showing the south-west area of the Langdon Hills Country Park as context to my sighting. I am confident there are numerous colonies in this area and probably north within Willow Park but the area lacks recorded sightings.

Northlands Wood - White-letter Hairstreak was seen on a single visit on the 25th of June. Total: 1

White-letter Hairstreak ovipositing
Northlands Wood 25/06/2024

I have included the locations of both of the sites that I would recommend to observe White-letter Hairstreak especially at 8.30 to 10 in the morning and between 4.30 and 6 in the early evening. Benfleet Downs as the site with the most recorded sightings, and Belton Hills Nature Reserve at Leigh-on-Sea is the site that is well known to butterfly enthusiasts.

North Essex

The following locations are where sightings of White-letter Hairstreak were recorded by me during 2024 within North Essex:

2024 White-letter Hairstreak recorded sightings
North Essex site locations

Friday Wood & Cherry Tree Lane

Friday Wood & Cherry Tree Lane

The mosaic of habitats in the Friday Wood area is definitely the place where I would expect to see a good number of White-letter Hairstreak in the hedgerows and scrub running along both sides of the lanes including Cherry Tree Lane and Bell Lane. Also, Middlewick Ranges to the east and Abberton Reservoir to the south are within walking distance. Obviously it will take patience and several visits during their flight period, particularly during the last week of June to the middle of July.

Friday Wood - White-letter Hairstreak were seen on a single occasion on the 11th of July. Total: 8

Essex Wildlife Trust Great Holland Pits Nature Reserve

EWT Great Holland Pits Nature Reserve

Another site that gives the visitor a good chance of seeing White-letter Hairstreak if they know the locations of the elms opposite the hide. It is also the place to wait patiently for White Admiral to settle. The lane running from the hide north towards the entrance to the heathland is also a popular location to view White-letter Hairstreak when they are active.

EWT Great Holland Pits Nature Reserve - White-letter Hairstreak were seen on a single occasion on the 22nd of June. Total: 3

I have added RSPB Abbots Hall Farm & Old Hall Marshes to the map as another recommended site to visit to see White-letter Hairstreak in the vice-county of North Essex. I am surprised by the lack of recorded sightings at Hatfield Forest.

Highlights
I think it is always an enjoyable surprise to watch White-letter Hairstreak when they are in flight going to and fro but always within a short distance from the trees where their colony is. I was happy to see 16 and at four locations especially as they were never the species I was especially targeting, although I was being vigilant. I found it very useful to search for the elms first and then find ones that were south-facing within either a woodland edge or along a hedgerow. To watch and photograph a White-letter Hairstreak close-up whilst she was ovipositing was a very enjoyable moment shared with a special butterfly. I am definitely going to spend more time looking for them especially during the morning at all the woodland sites I visit in 2025 with a visit to both Benfleet Downs and Belton Hills Nature Reserve.

[essexbuzzard]

Hi David, my comments above are not meant as a criticism of you or anyone else. Far from it. Rather, it is a plea for recorders in the county- myself included - to record what they see, and try to make the Essex maps a little more complete.

I’m not particularly computer savvy, but does the iRecord website have an app, which I can load onto my phone? I might be able to help, with sightings from the Harlow and Ongar areas.

I did see a White - letter Hairstreak in Hatfield Forest a few years ago, while looking for Silver- washed Fritillaries, so there is probably a population in there, somewhere. Unlike the Purple Hairstreak, I don’t think the White- letter is particularly common but, as you’ve said, very under recorded.

[David Lazarus]

Hi David, my comments above are not meant as a criticism of you or anyone else. Far from it. Rather, it is a plea for recorders in the county- myself included - to record what they see, and try to make the Essex maps a little more complete.

I’m not particularly computer savvy, but does the iRecord website have an app, which I can load onto my phone? I might be able to help, with sightings from the Harlow and Ongar areas.

Hi Mark, don’t worry, I understood what you meant. I am glad you recognise the constraints that researchers are under. Like you I would encourage everyone with a concern for butterfly conservation [especially in Essex ] to download the iRecord Butterflies app, which is available both on iPhone and android, and start recording sightings. A link for further information is below:

https://irecord.org.uk/app#:~:text=iRec ... education.

As I have mentioned, I have just started a 10-year project The Butterflies of Essex which I hope will be a valuable contribution to butterfly conservation. At the moment I am creating reports for each of the 34 species found in Essex. My attempt to construct a baseline to work from is proving more frustrating than I expected due to the lack of data available in the public realm. I have to assume organisations, such as Butterfly Conservation, have more comprehensive data with records going back a century or more.

Some good news at least, I now have access to download all records on iRecord which will mean I can total up all recorded sightings and show abundance figures for location and date - although this is not easy for a variety of reasons. I think it should show the flight period for species in Essex which would be useful.

I shall make an attempt today on the next species, the wonderful jewel of a butterfly, the Small Copper.

All comments, views, or help in any way is more than welcome and will be appreciated as I attempt to improve my report writing and presentation. I am just a beginner and value all of your experience and am enjoying being part of the UK Butterfly community immensely.

[Butterfly_Julian]

Hi David, as always the info is very informative, I have to take my hat off to you for all the work you have done and will be doing over the coming years.

I love getting out locally looking for new colonies of the Hairstreaks. Was great to find the Green Hairstreak behind out cottage and a Purple Hairstreak colony on a building site I was work at in Kirby Cross. I was surprised at the amount of activity at low level at 7:30am on a sunny morning.

You are spot on with the area at Great Holland Pits for seeing the White-Letter Hairstreak. I believe I recorded 18 individuals on one visit towards the end of June. The added bonus of this site for seeing them is the row of Elm suckers between the path and the Heath which are 3 and 4 metres high.

Keep up the good work David.

Julian

[David Lazarus]

You are spot on with the area at Great Holland Pits for seeing the White-Letter Hairstreak. I believe I recorded 18 individuals on one visit towards the end of June. The added bonus of this site for seeing them is the row of Elm suckers between the path and the Heath which are 3 and 4 metres high.

Thanks Julian, your comments are much appreciated, as usual. And really useful to have your local knowledge. I did not know about the elm suckers along the path & the heath. Sounds like a good place, low down enough to get good views, and hopefully should be with us for a few years.

I thought you might be interested in the following - a draft version as I am still practicing using all records now that I am able to download them.

The Butterflies of Essex
2024 Year in Review

White-letter Hairstreak Appendix

The 2024 abundance by location for all records is as follows:

2024 White-letter Hairstreak Abundance by Location

The 2024 Flight Period for the White-letter Hairstreak within Essex approximates to the following:

2024 White-letter Hairstreak Essex Flight Period

The recorded sightings for the White-letter Hairstreak within Essex occur from the 12th of June at Benfleet Downs to the 07th of August at West Wood, peaking around the 28th of June at Great Holland Pits.

Very provisional but gives us a glimpse of what is happening.

And as close as I can come to a distribution map with an overlay from the Essex Field Club website filling in the spaces of the maps I have already produced - the first recorded sighting was 1983 and 55 Hetrads are covered:

White-letter Hairstreak Distribution Map
Source: iRecord & Essex Field Club

I hope that helps for those who live in Essex to search for the colonies of White-letter Hairstreak that are out there.

[Butterfly_Julian]

Excellent David.

A question if I can, you probably don't know compared to previous years how does the abundance compare and with so many low counts at most sites, do we / or can we have any idea of population size for each site? What i mean is if 3 butterflies are seen most years for the last, say 10 years, that site will have, say min 20 individuals there to keep the gene pool substanable and that population viable.

[David Lazarus]

Excellent David.

A question if I can, you probably don't know compared to previous years how does the abundance compare and with so many low counts at most sites, do we / or can we have any idea of population size for each site? What i mean is if 3 butterflies are seen most years for the last, say 10 years, that site will have, say min 20 individuals there to keep the gene pool substanable and that population viable.

Great question, Julian. I can now definitely produce tables and graphs for all Essex recorded sightings on iRecord for every year since the records began. It will take a little time.
Then someone, with a lot more experience than me, could maybe give us an idea of what the data reveals, if anything. This is especially true for a butterfly species like White-letter Hairstreak as I know very little from experience and field surveys/observation - although hopefully that will grow over the next few years. What I do know and mentioned above, is that colonies of White-letter Hairstreak go largely under-estimated because of their arboreal habits and inconspicuous nature. So, to see 18 at Great Holland Pits on the same day at two or three locations would imply a healthy and sustainable colony or two operating with a relatively large gene pool.

So yes, definitely on my list of things to do on a rainy, cold, cloudy, windy day…. Watch this space.

As an example, here is the abundance year-on-year at Great Holland Pits:

Total Abundance Year-on-year
EWT Great Holland Pits 2021-2024

And this is easy to explain: During 2021 and 2022 White-letter Hairstreak were only recorded by one recorder, Bob, and that was on his transect. As far as the records go, his transect data is only from the last 4 years, not 40. Then add two new recorders, yourself and me, who are recording what they see on site visits, the number of recorded sightings go up substantially. This is to be expected because we are relatively experienced butterfly recorders and know where to find them. So, as you can see the data tells us very little. Firstly, there is a lack of data much of which is recorded on a transect which does not lend itself to recording White-letter Hairstreak - I would suggest Bob's recordings probably pushed the boundaries of the 5-metre cube limits. But it also shows what can be achieved by recorders counting their sightings during site visits within the flight period of the species they are targeting. However, this is only useful when repeated over at least 5-10 years.

What it does not tell us is anything about the health of the colony year-on-year but it does show us that there is a healthy colony or two or three, depending on the locations, at Great Holland Pits in 2024 as the total of 47 is very good for one site.

For the whole of Essex, recorded sightings on the iRecord website only go back to 2005 - 20 years of data. The sightings on the Essex Field Club website go back to 1981 to 2023 but the data cannot be downloaded although it can be requested by members. The data available to answer your question is unfortunately limited. On a UK level Butterfly Conservation can observe the trends but I think they use an algorithm to smooth the data. Anomalies like my own data collected during 2024 could give the impression that, for example, Wall abundance and distribution in Essex had increased significantly, when in fact I know that it shows that, unlike previous years, I was out there targeting Wall in places they had not been recorded and/or at a time when numbers were significant.

I will have a look at Benfleet Downs next.

[David Lazarus]

The Butterflies of Essex - 2024 Year in Review

White-letter Hairstreak Appendix

Benfleet Downs

Recorded sightings have occurred at Benfleet Downs since 2010 predominantly from one person's transect. The following table shows the abundance year-on-year:

White-letter Hairstreak
Benfleet Downs 2010-2024

This is the only site in Essex where there is sufficient data to analyse and make an evaluation. The transect shows that the abundance has reduced by around 50%. Whether this is the case across the whole of Essex is hard to tell given the available data but it is generally considered that there has been a moderate decline in abundance within Essex. I would suggest that is an under-estimate and that there has been a serious decline in abundance since the turn of the millennium.

Benfleet Downs within Hadleigh Country Park is considered the hotspot for White-letter Hairstreak sightings within Essex by butterfly enthusiasts, several of whom visit the site annually during the peak flight period. The health of the elms and the quality of management for the conservation of this species is a concern. The walk from Leigh-on-Sea railway station via Belton Hills Nature Reserve adjacent to the station's car park through Hadleigh Country Park and Hadleigh Castle to Benfleet Downs is the butterfly walk to see White-letter Hairstreak in Essex with the additional delight of a mosaic of habitats suitable for a good selection of the other butterflies of Essex.

[essexbutterflyer]

[quote="David Lazarus" post_id=189895 time=1739790231 user_id=22825

Benfleet Downs within Hadleigh Country Park is considered the hotspot for White-letter Hairstreak sightings within Essex by butterfly enthusiasts, several of whom visit the site annually during the peak flight period. The health of the elms and the quality of management for the conservation of this species is a concern. The walk from Leigh-on-Sea railway station via Belton Hills Nature Reserve adjacent to the station's car park through Hadleigh Country Park and Hadleigh Castle to Benfleet Downs is the butterfly walk to see White-letter Hairstreak in Essex with the additional delight of a mosaic of habitats suitable for a good selection of the other butterflies of Essex.
[/quote]

I suppose this begs the question of what is being done to help the Hairstreaks? I have heard often that disease-resistant elms are available, but I cannot remember any instance i have come across of them being used to support White-letter Hairstreaks

[David Lazarus]

I suppose this begs the question of what is being done to help the Hairstreaks? I have heard often that disease-resistant elms are available, but I cannot remember any instance i have come across of them being used to support White-letter Hairstreaks

As you go to college in Brighton, I thought I would draw your attention to the project at Lancing College, where 550 disease-resistant elms have been planted to support White-letter Hairstreak. More info: https://butterfly-conservation.org/in- ... 0on%20elm.

I’m not in favour of planting cultivars in the wild especially as we have Wych Elm Ulmus glabra which is more disease-resistant than our other native species. I think we will probably have to get used to the new norm whereby White-letter Hairstreak will use the flowering suckers of disease-ridden elms. When the suckers themselves succumb to Dutch Elm Disease, the hairstreak will move on to the next suckers when they have reached an age when they produce flowers. I think the White-letter Hairstreak is already adapting to survive. I do believe we can manage the habitat so that there are always a plentiful supply of flowering suckers for the colony to use. And plant more Wych Elm in rides, woodland edges, and hedgerows. We can create corridors and patches of suitable habitat close to known colonies to support an increase in the range and connection to other known colonies. It would help if we knew where the remaining colonies in Essex are.

[essexbuzzard]

Hi David.

Hadleigh Castle County Park has, indeed, seen a decline in WLH. I used to visit regularly, but the butterfly there faces three threats. Firstly, some of the elm was sacrificed to make way for the mountain bike trails following the London 2012 games. More recently, more was lost to increase the meadow areas, to help the shrill carder bee. A noble aim, perhaps, but at the expense of more WLH habitat, including the brambles the adults fed on. And lastly, much of the remaining elm seems to have been dying back in recent years. Hopefully it will recover in time, but these three combined have led to a reduced population.

[David Lazarus]

Hadleigh Castle County Park has, indeed, seen a decline in WLH. I used to visit regularly, but the butterfly there faces three threats. Firstly, some of the elm was sacrificed to make way for the mountain bike trails following the London 2012 games. More recently, more was lost to increase the meadow areas, to help the shrill carder bee. A noble aim, perhaps, but at the expense of more WLH habitat, including the brambles the adults fed on. And lastly, much of the remaining elm seems to have been dying back in recent years. Hopefully it will recover in time, but these three combined have led to a reduced population.

Thanks, Mark, it is always good to hear from experienced butterfly enthusiasts who have local knowledge. I did hear about the decision to remove certain elms. Unfortunate . I hope the colony or colonies will be able to survive. Hopefully, the park wardens will choose to plant small groups of Wych Elms or disease-resistant elm cultivars [which is probably all they will be allowed to source] to support White-letter Hairstreak. I am assuming the destruction of their habitat has been brought to their attention?

[Matsukaze]

Perhaps the best way of mapping WLH is searching for the early stages, especially the larvae, which have the useful advantage that they do not disappear on grey or wet spring days, and can usefully be surveyed when there are no adult butterflies to be seen. For matters WLH-related check out https://www.hertsmiddx-butterflies.org. ... /index.php, which features most of the adjacent counties to Essex.

[David Lazarus]

The Butterflies of Essex
2024 Year in Review

Small Copper Lycaena phlaeas

Summary
The Small Copper is of Least Concern in the vice-counties of North and South Essex, and is considered the lowest priority when it comes to butterfly conservation. It is described as being a common and widespread species within Essex, but the Small Copper has declined throughout its range. It is usual for me to see no more than ones or twos. I have never seen double figures at a site visit, certainly not in 2024. There have been many sites that I have not recorded a sighting. There were no sightings of Small Copper in my local meadow at Meadgate Fields Open Space - I suspect it had a tough time locally and unfortunately may have suffered local extinction in that particular meadow. I suspect as a sun-loving species of open ground habitats, the dull and overcast conditions, particularly during spring and early summer, did not favour their life cycle. It is clearly quite local in distribution at low density and in small colonies - at least where I have visited during the last few years in Essex. It is always a pleasant surprise to see this jewel of a butterfly. Personally, I think we need to keep a close eye on their abundance and distribution within Essex. We probably need to take a close look at some open ground habitats that they favour, especially the remaining heathland, and decide to proactively take conservation action to support them. It is 26th out of 34 in the 2024 Butterflies of Essex list of species abundance - the last species of those considered "common". It is behind the Small Tortoiseshell, and I would consider the Small Copper to have had a really difficult year - I would not call it common or widespread within Essex.

I am finally able to download all iRecord records for butterflies in the vice-counties of North & South Essex. That means I can produce more accurate distribution maps and abundance tables to analyse and evaluate what is going on in Essex - although, as I mention consistently, the lack of recorded sighting data for Essex limits my ability to do so.

Small Copper records for Essex surprisingly go back to 1976 although I have noticed the records have been submitted by one person at one site - Two Tree Island. The data allows us to create a distribution map for the Small Copper, limited to records submitted to the iRecord webiste:

Small Copper Distribution Map for Essex
Source: iRecord

Although reasonably widespread the only places with moderate to high density are in the Epping Forest area in north-east London, locations in south-east Essex along the Thames estuary, Chelmsford and mid-Essex, and the usual sites located in the north-east of Essex.

Surprisingly, the distribution map created by the Essex Field Club from data they have collected since 1990 to 2023 shows a much more widespread distribution with few hetrads that have no recorded sightings.

Small Copper Distribution Map for Essex
Source: Essex Field Club

The overlay of the Essex Field Club is significantly different from that of the iRecord map:

Small Copper Distribution Map for Essex
Source; iRecord with Essex Field Club overlay

I would be surprised if the above maps represent the true distribution of the Small Copper as it is in 2024. We can compare the records collected over the past twenty years which can provide a glimpse into the change in its range compared to the "distribution map" for all records, bearing in mind the recent change in record collecting, especially with the introduction of mobile applications.

Small Copper 2005-2014 recorded sightings
Source: iRecord

Small Copper 2015-2024 recorded sightings
Source: iRecord

I think these show that records collected for use in the iRecord database has notably increased in the last decade compared to the previous decade. I certainly do not think that it shows that the range of the Small Copper has increased. The recorded sightings for 2024 has reduced significantly compared to all records collected during the past decade:

Small Copper 2024 recorded sightings
Source: iRecord

A shocking decrease in range or a lack of data to evaluate?

The 2024 abundance by location shows those locations where records have been collected:

Small Copper Abundance by Location for all 2024 recorded sightings
Source: iRecord

Quite clearly there are few locations where numbers of recorded sightings have been good, and these locations are those that have transects. There are many sites that are good for butterflying, yet recorded sightings of Small Copper are frighteningly low. A grand total of 497 recorded sightings of individual butterflies in the vice-counties of North & South Essex, of which 53 were my own, seems very low.

One of the most useful tables is the 2024 abundance by date of recorded sighting which shows that despite the poor season, the Small Copper still managed to have three broods with the third brood quite a bit larger than the others. It also shows that the summer brood was very poor which is to be expected given the weather conditions. There was a late season recovery which was good to see.

Small Copper Flight Period
Source: iRecord

My own data is not sufficient to draw any conclusions but will provide a baseline for subsequent years. The following map shows the sites where my Small Copper sightings were recorded during 2024:

Small Copper recorded sightings during 2024
Small: iRecord

And the abundance at these sites reveals the low numbers that I recorded even at sites that have suitable habitats for the Small Copper:

Small Copper 2024 Abundance by Location
Source: iRecord

I did not see double figures at any location during the whole of the Small Copper's flight period let alone seeing more than single figures during any one site visit. In fact, as the recorded sightings by date of site visit shows, 6 on one day, the 11th of September, was the most I saw. This was not even at one site but two with 4 at Lingwood Common being the most Small Copper I saw on one site visit during 2024. And not surprisingly, Lingwood Common was the site with the highest number of individual Small Copper seen during 2024. 21 of the Small Copper I saw during 2024 were in Chelmsford and mid-Essex. A further 21 were seen during my trek around the Essex Saltmarsh Coast during September and October. Most of my sightings were during the third brood.

Small Copper 2024 Abundance by Date

My first sighting of a Small Copper was on the 01st of May at One Tree Hill in Langdon Hills Country Park with the highest number seen on one day on the 11th of September at Lingwood Common and Danbury Common. 30 of the 53 recorded sightings were seen during September and October with the final sighting on the 16th of October at Freshfields on the Blackwater Estuary near Maldon. My experience was the same as the data collected from all records with three broods - 9 in the Spring Brood, 14 in the Summer Brood, with the highest number of 30 during the Third Brood.

Highlights
There were very few highlights although I did manage to spend some quality time with a female as she searched the undergrowth in pursuit of the ideal place to position her ova. She decided on a bramble runner hidden in the long grass. I also think seeing more than expected around the sea wall along the Essex Saltmarsh Coast was some good news in an otherwise poor season for the Small Copper.

Small Copper ova
Friday Wood 11/07/2024

[David Lazarus]

Perhaps the best way of mapping WLH is searching for the early stages, especially the larvae, which have the useful advantage that they do not disappear on grey or wet spring days, and can usefully be surveyed when there are no adult butterflies to be seen. For matters WLH-related check out https://www.hertsmiddx-butterflies.org. ... /index.php, which features most of the adjacent counties to Essex.

Yes, I am planning on getting out there to take a look at a couple of sites - and hopefully find an ova or two. And thanks for providing a link to the very useful site you suggest.

[David Lazarus]

The Butterflies of Essex
2024 Year in Review

Brown Hairstreak update

Another location discovered in Essex this winter where ova of Brown Hairstreak has been found.

Epping Forest: Fairmead Road - 19/02 Total: 1 ova

As of 22/02 known locations of Brown Hairstreak in Essex:

Claybury Park
Rainham Marshes
Whitehall Plain - Chingford Plain
Epping Forest: Fairmead Road
Chigwell Row Wood

Very good news for the conservation of the Brown Hairstreak in Essex.

[bugboy]

As I understand it, BH have been routinely introduced in Epping Forest for several years. Not sure if they've ever got a proper foothold there. (I could be wrong about this and got the wrong end of the stick somewhere along the line though....)

[David Lazarus]

As I understand it, BH have been routinely introduced in Epping Forest for several years. Not sure if they've ever got a proper foothold there. (I could be wrong about this and got the wrong end of the stick somewhere along the line though....)

Thanks for raising this, Paul. You are not wrong. According to the Essex Field Club there is substance behind the issue of their reintroduction by lepidopterists into the Epping Forest area:

“The very recent detection of the brown hairstreak as a breeding species in Epping Forest is another mystery. Undetected survival of a colony is certainly possible with such secretive species as hairstreaks. On the other hand, deliberate introductions, in other counties, of the ecologically similar black hairstreak have been very successful (Heath et al). So an unrecorded successful introduction may explain the Epping Forest brown hairstreaks.”

Source: Essex Field Club https://www.essexfieldclub.org.uk/archi ... 105/o/0021

Sorry, I don’t know when that was written or by who.

Writing in 1997 David Corke states that the Brown Hairstreak was once resident but is now extinct with no post-war sighting records. He goes on to say that a “reestablishment experiment in Epping Forest is planned”. [Corke D., & Goode B., 1997 The Butterflies of Essex Lopinga Books.

In 2023, Ian Watts from our branch wrote “The Brown Hairstreak had been missing from the Cambridgeshire & Essex Branch area for generations but the sighting of an adult in Chigwell Row last summer and the exciting discovery of eggs in Claybury Park in December means this species may be resident once again in Essex”.

Two years later 100+ ova found at Claybury Park plus ova at 4 other sites - plus probably 10 or 11 individual adult sightings during 2024.

My own personal opinion is I do not condone amateur lepidopterists reintroducing extinct species unofficially. I am particularly against people harvesting ova from the wild to introduce somewhere else. However, a couple of years after their first sighting, Brown Hairstreak colonies exist in Essex and are successfully laying ova and adult sightings are being recorded - and I am super happy about that. I hope more locations will be found and they expand their range however it came about. It is not inconceivable that they have gone unnoticed and/or are part of an expansion of their range - granted the maps in my review hardly support that opinion.

I would also say that more effort is being put in to finding them and recording the adult sightings and ova counts. It would not surprise me if we found more locations and see more adults on the wing - I hope it is me who sees them.

[essexbutterflyer]

Fascinating David. I wonder if Brown Hairstreak is going to be officially recognised as present in Essex again…