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A species focus on the Heath Fritillary in Essex: status - highly threatened
28/06/2024 Site visit: South Essex woods

In The Heath Fritillary in Essex - 2015 report, produced by the Essex Wildlife Trust Biological Resource Centre, the collected data for adult trends showed that the populations in the four Essex woods in which the Heath Fritillary was introduced were still in decline and that the butterfly was severely threatened with extinction.

The report contains the following conclusions for each of the woods:

1. Hockley Woods
Population Trend: stable, following severe decline
Population Status: at risk

2a. Hadleigh Great Wood
Population Trend: severe decline
Population Status: severely threatened

2b. Dodds Grove
Population Trend: stable at low levels
Population Status: severely threatened

3. Pound Wood EWT
Population Trend: severe decline
Population Status: severely threatened

4. Thrift Wood EWT (SSSI)
Population Trend: severe decline
Population Status: extinct (2014 to present)
There are no plans for EWT to reintroduce the Heath Fritillary at this site despite the wood sustaining a population for 30 years up to 2013.

This leaves the three sites Hockley Woods, Hadleigh Great Wood & Dodds Grove, and Pound Wood with the Heath Fritillary continuing to be a highly threatened species vulnerable to extinction at all three woods in Essex. These are the three sites that I have collected data and observed the health of the Heath Fritillary and the patches of Common Cow-wheat Melampyrum pratense, an annual plant, on which it depends.

Nearly ten years later, the Essex Wildlife Trust this week released a news article entitled Highest number of heath fritillaries recorded where they state that the record numbers of 148 heath fritillary butterflies were announced in 2019, and that record was beaten in 2024 during which 218 were recorded at Pound Wood nature reserve in south Essex, making it the highest number the Trust has seen to date. [source: https://www.essexwt.org.uk/news/highest ... s-recorded].

I have visited 4 times during the last month with my penultimate visit taking place on Friday 28th June last week. Although the weather conditions were not ideal for this warmth and sun-loving butterfly, it was sufficiently good enough during the brief sunny intervals to collect data on adult numbers. My final visit next week will be subject to the weather with the forecast not great.

Hadleigh Great Wood has one tatty female left signalling the end of the flight period for 2024 at this site for another year especially given the cool, wet weather forecast for the next four days. I personally have not seen more than 4 at this site in only one colony of the two places left with sufficient cow-wheat to sustain a population. Others have found 12 or so. No one has found Heath Fritillary at Dodd's Grove and the glade is not currently in a state to attract further colonization.
The news is far better at Pound Wood and Hockley Woods where the main colonies now reside. I counted 55 Heath Fritillary at Pound Wood on Friday down from a peak of approximately 100. At Hockley Woods I counted 59 which is down from a peak of between 200-250 individuals. Over the 3 woods, I would say the peak count for 2024 was around 350. I would question the count of 500 at Hockley Wood on one day as a significant exaggeration. I actually think the EWT's count of 218 was probably an over-estimation being double the amount I saw on two occasions during the peak flight period.

It will probably be no surprise to you that at both sites there were fewer males seen than on previous visits. There were some freshish-looking females at Pound Wood:
and this included some being pestered by males and some laying eggs:
But you are more likely to see this now at Pound Wood:
than a few of these:
But there is always the occasional beauty to behold:
It is much the same at Hockley Woods in the main four colonies within the South Essex Woods, with significant reductions in abundance and what is there containing a higher percentage of females that have been around for a week or so:
with a few newly emerged ones:
the odd dead one:
but the majority are not looking at their best:
having said that, there is still a bit of activity going on:
It has been a joy and delight to be amongst this beautiful, delicate, and vulnerable species for the past month. The Heath Fritillary is one of my favourite butterflies and I cannot wait to do the whole thing again in 2025 and beyond.

One sadness was the amount of flattened vegetation. Unfortunately, I suspect most of this was the result of butterfly enthusiasts attempting to acquire the perfect shot while ignoring the fact that there was plenty of larva and pupa under their feet. Some of the areas in both Hockley Woods and Pound Wood had grass patches that had been trampled on resulting in significant loss of perching, basking, & roosting sites as well as places that the Heath Fritillary enjoy meeting the opposite sex. The Heath Fritillary also lays it's eggs low within the grass and plant litter close to the cow-wheat. Please, if you are going to the woods, keep to the paths or the visible trails through the cow-wheat, and don't venture off them into the vegetation even if it is grass or over plant litter - certainly please do not trample on the cow-wheat. And please watch your feet as they are low flying and regularly rest on the floor within vegetation and leaf litter.

Enjoy, and celebrate the fact that 2024 had a healthy emergence of Heath Fritillary in Essex.

I'm right behind you on that one, David. The trampling of foodplants, nectar plants and anything else that might come between a photographer and that perfect photo is the main reason I never publicise my sites. They say, 'Take only photos, leave only footprints', but I believe you should try very hard not even to leave footprints (and certainly not body rolls).

Bizarrely, I think I might never have seen a heath fritillary, Melitaea athalia. I've never seen one in the UK, and all the heath fritillaries I've seen in Europe are within the range of the recently split Melitaea nevadensis. Maybe back in the Brenne when I was a schoolboy ... Anyway, I ought to make it a mission for next year! You have some great photos of the Essex heath frits.

Guy

Padfield wrote: ↑Sun Jun 30, 2024 6:11 pm I ought to make it a mission for next year! You have some great photos of the Essex heath frits.

It would be my pleasure to show you the hot spots when you are next in Essex, Guy - message me when you are back in the UK. At the moment, I am with you about advertising the sites. However, in this case everyone knows where they are [to a certain extent] and when they are flying. The exact hot spot locations are not universally known. I want signage to be put up for next year saying please keep off the conservation area which others may say shows the hotspot locations. But I think there needs to be some balance by letting butterfly enthusiasts know about the health of this wonderful butterfly whilst emphasizing their role in being responsible for the conservation of this vulnerable and highly at risk insect, not only in Essex but the UK.

Thanks ... the photos are just a snap shot of week 4 post-peak. I have some absolute stunners from weeks 2 and 3. I was determining the percentage of sexes in the colonies. As you probably know they are easy to photograph when they are waiting for the sun to come out - I took photographs of each of the first 75 individuals [out of 81 in the colony at Pound Wood] that were easily reached along the paths and trails. I am hoping to complete a report of the season at some point - I will include some.

Many thanks for that report, David. This is an exceptionally common butterfly in continental Europe so it's easy to forget how precious it is in our own country.

I hope these declines can be reversed.

Some excellent background info on the Heath Fritillary populations in Essex, David. I have regularly visited Both Hockley and Pound Woods over the last 15 years and have noted considerable fluctuation in numbers. I've also seen them at Little Haven (close to Pound Wood and along the same power transmission line: they were flying in the wayleave under the wires), but I think that colony died out. However, it's great to hear that numbers are up this year (something mirrored in the large colonies over in Kent in Blean Woods, I believe) and the declines noted in 2015 have been halted. Certainly on my visit to Pound Wood on 23rd June, there were plenty around.

Cheers,

Dave

11/11/2024 Site visit: Friday Wood & Cherry Tree Lane
Friday Woods, part of the Roman River Site of Special Scientific Interest, is an ancient woodland, modified in places by plantations of conifers and sweet chestnut. It is part of the government's Defense Estates and hosts a military corrective training facility. There are also three working farms and private property restricting access in some places. Overhead electric pylons run straight through the centre of the area of interest.

It is composed of an intricate mosaic of habitats including secondary woodland and scrub interspersed with open grassland and heathland, with wetland habitats in the valley bottom to the south. Further south is Abberton Reservoir into which the Roman River drains, and where there is an Essex Wildlife Trust Nature Discovery Park.

The habitats within the Friday Wood and Cherry Tree Lane area are famous for the almost one thousand types of butterflies and moths that have been recorded there, including numerous rare species. It is one of the best sites for butterflying in Essex for both woodlanders and open ground habitat species.

It was my first visit in my quest to discover and map the main hot spots for sighting Purple Emperor, White Admiral, and Silver-washed Fritillary, as well as the Hairstreaks, and anything else that might appear during my visits.

I could have chosen a day with better weather conditions for my visit, but I was desperate to get out and about after days of what is becoming a disappointingly dull, wet, overcast July 2024. It remained grey overhead with sporadic sunny intervals. The light winds made it feel cooler than the 17C temperatures. Because of this the butterflies were inactive for most of the day, which made it easier to approach and photograph grassland species but frustrating to accomplish my main objective of tracking down the haunts of the premium woodland species.

I arrived at around nine o'clock in the morning at the north east access point and put in a nine hour shift analyzing and evaluating the habitats, GPS mapping the most likely places to view butterflies, as well as looking out for and photographing the odd butterfly here and there. A very interesting day, despite the weather. Most importantly, perhaps, I continued to learn about butterflies and their habitats.

Not surprisingly, given the dull cool morning with dew still on the vegetation, the Ringlet was the first butterfly to take to the wing. The first of 68 Ringlet, continuing what appears to be a good year for them in 2024 here in Essex - at least, it feels like a better year than 2023:
As it was so grey and a little cool I kept to the open areas where a few butterflies could be seen. The first thing that caught my eye was how light the Meadow Brown were - much lighter than the very dark ones I see around my local patch to the south. I think these are some of the lightest I have ever seen anywhere:
And this female is particularly striking, I think:
I recorded 148 Meadow Brown in total across the site, this being the highest species count for Friday Wood. However, this is definitely a 500+ site given optimum weather conditions and the vast areas of open grassland.

The Gatekeeper numbers are continuing to rise in Essex as more of these beautiful butterflies emerge - 39 in total but once again this is a 300+ site with the amount of woodland edge, scrub, and adjacent tall grass to be found. I saw some stunning individuals with this very vibrant, dark male, that had immaculate white fringes, taking top spot:
The morning could not be complete without a skipper density count whilst they were predominantly sedentary. No surprises, being Essex, that of the first 25 that I identified I did not find a single Small Skipper. This would be the case until the last moment before I headed home. In total I had 30 confirmed sightings of Essex Skipper including a male version of the ones with dark bleeding into the veins:
At around midday a sunny interval descended and I quickly ran to an area I had identified earlier as a possible hot spot for Purple Emperor with a mix of Grey Willow Salix cinerea & Goat Willow Salix caprea scrub with Pedunculate & Sessile Oak standards Quercus robur & Quercus petrea respectively:
At this point in the wood there is a small open area at a dip in a ride which acted as a sun trap - south-facing:
And it is here that I witnessed a dog fight between two male Purple Emperors. There were also three male Silver-washed Fritillary gliding around and investigating any insect that moved whilst settling on the brambles and taller herbaceous plants - but too far away from me to photograph. A little further up the hill to the east there were another couple of SWF as well as a passing White Admiral. As quickly as the full sun appeared, it was gone and pretty much for the rest of the afternoon also. And disappointingly that meant the end to any chance of recording any further sightings of the woodlanders.

To be continued.