Max Anderson

[Max Anderson]

I thought it would be worth startying a personal diary of my own so that I can share my experiences and photos.

I will aim to put together longer posts on an infrequent basis, rather than posting regularly with findings from a single day.

Hope my posts can be of interest!

[trevor]

Welcome Max!. And good to meet you again today.
Look forward to your posts and images.

All the best,
Trevor.

[Katrina]

Welcome from me too!

[Max Anderson]

Long-tailed blue

There has been a fair bit of noise generated by the long-tailed blues at Whitehawk hill (Sussex) over the past few weeks. I thought I would provide my angle on some of the events I was fortunate to observe, in the hope of providing a different perspective.

6th August 2020

After reading about a sighting of a single indiviual from whitehawk hill on 5th August, I headed over from 10:00 - 12:00, but I was unable to find any individuals. I suspect the sub-optimal weather conditions were to blame.

7th August 2020

I returned the next day for 09:30 and within about 5 minutes, I had spotted a single female, nectaring from the broad-leaved everlasting pea (B-LEP) and egg laying.

9th August 2020

I headed back again, this time with the intention of also searching for eggs. Again, it took me very little time to locate the same female as seen on the 7th. After chasing her around for a while I then spent around 20-30 minutes searching a patch of the B-LEP and counted 7 eggs.

17th August 2020

When I returned to the same patch of B-LEP where I had previously conducted the egg count, unfortunately there was noticeable tramping damage and I was only able to locate 3 of the eggs, all of which had hatched. The trampling damage is regrettably, an inevitable part of the process, as the long-tailed blue attracts a lot of attention from enthusiasts across the country.

There also appeared to be a small hole on the flower receptacle, which I strong suspect is created by the catterpillar as it feeds on the developing flower.

9th September 2020

When I arrived at Whitehawk hill, there was already a group of people at the patch of B-LEP adjacent to the allotments. They had already seen a fresh female and we began to watch as groups of 3, 4 and 5 males battled and spiraled high up in the air. After a short while, I wandered around the site to see if any other patches of B-LEP had any activity, but there was none to be found other than within close proximity to the patch adjacent to the allotment. I frequently observed battling males fly away from the allotments and disappear near a stand of bramble, sheltered by some bushes. Despite having no B-LEP, there was a good level of activity, and I suspect the strucutre of the vegetation and resulting microclimates was partly responsible. Later on in the day, Neil Hulme called my attention as he spotted a male and female amongst the bramble patch. After some very persistent work from the male, he successfully clasped onto the unimpressed female (See https://youtu.be/RyEIQ_v-Z_E) , and they were together for around 2 hours before we all left. They would likely be there until morning. Overall estimates from the action-packed day: 2 females and 9 males, including the mating pair.

14th September 2020

The warm weather and reports of increased activity at Whitehawk Hill tempted me back out. I arrived at 09:45 and there were already a number of people crowding around adjacent to the allotments. I drifted away from the crowd to the sheltered spot that had previously produced some good activity and spent some time observing the behaviour of males. As usual, they were incredibly habitual and predictable in their choice of basking spots, most often choosing to land on conspicuous, tall strands of vegetation. At two other B-LEP patches further from the allotment, I found one male, nectaring before moving on.

Before heading back home, I visited a good-sized patch of B-LEP near Southwick to check for any activity, but saw nothing over the course of an hour. From what I understand, the hilltopping behaviour of long-tailed blues is a significant factor behind the success of the population at Whitehawk hill. I would be interested to see whether some spatial modelling of topography and occurence of B-LEP might allow us to predict where migrating long-tailed blue butterflies are most likely to occur.

[Benjamin]

Nice one Max - good to get your perspective. Glad you’ve started a diary - one to keep an eye on for sure.

[Neil Hulme]

I'll second that. Great stuff!

"I would be interested to see whether some spatial modelling of topography and occurence of B-LEP might allow us to predict where migrating long-tailed blue butterflies are most likely to occur." I think the short answer is "yes". I think there will be plenty of more isolated sightings, which appear rather random in their distribution (although mostly, but not exclusively, within c.10 km of the coast), but the highest concentrations already appear heavily skewed towards topographical high points and river valleys, especially where the two are found in close proximity.

I love your blackberry shots.

BWs, Neil

[trevor]

A great and very interesting report, Max, backed up with some excellent images.
Also following the progress of the Whitehawk LTB's over such a long period is to be admired.

It seems an age ago that we were trying to sort out fresh Wood Whites from the remaining
spring brood specimens at Chiddingfold.

Stay safe and well,
Trevor.

[millerd]

A fascinating in-depth analysis, Max.

One of the other known "hotspots" where LTB have regularly appeared is along the clifftop near Kingsdown (between Dover and Deal) in Kent. From what I have heard they are back again this year. There are decent amounts of BLEP here, and obviously it is the shortest distance for a migrating butterfly to fly to the UK (though 35km is a mere trifle for the near-panglobal species that is the LTB). I imagine this clifftop site fulfills the hill-topping criteria the butterfly seems to prefer. However, they have also been found in previous years near the north Kent coast, in flat, low-lying areas where BLEP grows along embanked paths raised only a little above the surrounding marshy land. Here, perhaps the attraction of a suitable food plant overcomes the less favourable aspects of the area.

Hopefully the now regular migration of the species to the UK will allow more detailed studies of their behaviour. I for one am looking forward to reading further insights you have and seeing the excellent illustrative photos that accompany them!

Cheers,

Dave

[David M]

I thought it would be worth startying a personal diary of my own so that I can share my experiences and photos.

I will aim to put together longer posts on an infrequent basis, rather than posting regularly with findings from a single day.

Hope my posts can be of interest!

Welcome, Max. You've certainly got off to a flier - your report of your experiences with the Long Tailed Blues is of great interest.

I shall look forward to reading more.

[Wurzel]

A cracking start Max - those shots on on the Blackberry are lush Looking forward to more reports and as for the LTBs I just wish they'd move a bit more to the West though if this becomes a more regular migration then perhaps they'll arrive in greater numbers and fan out more?

Have a goodun and stay safe

Wurzel

[Neil Freeman]

Really interesting reports with great photos to kick off your PD Max. I am looking forward to seeing your next posts.

Cheers,

Neil.

[Max Anderson]

Thank you all for the kind comments. I'm looking forward to contributing again soon.

[Max Anderson]

Purple emperor

From mid-June to early July, I spent many early mornings patrolling the woodland rides in search for the purple emperor, working late into my evenings to make up for lost time.

Below is a short account of a few select days from the 2020 season:

16th June 2020

I spent a good 2 hours trawling the network of paths through Chiddingfold forest, looking for willow and oak trees along woodland rides with sunny spots. From my research, I noted that photos were often taken at points where the rides opened up slightly, or occasionally at crossroads, and so I made a mental note of those locations when I came across them. I also noticed that there were a few references to the occupation of ‘master trees’ at high points in the landscape, however I couldn’t find any substantial evidence to back up these claims. The term ‘master tree’ is something I’ve grown more and more sceptical of. It seems to only serve as a term which identifies a tree where significant activity was observed. I find that it tends to be over-used and often in an unreliable and inconsistent way. If anyone has any reason for me to change my mind, I would welcome their comments.

Chiddingfold forest has quite an extensive network of woodland rides, many of which look to be highly suitable for purple emperors, and so I thought it would be best to continue to cover ground in order to maximise my chance of seeing an individual. Bringing a bike would be a smart decision. It took all of 2 hours until I stumbled across my first. At a high point in the forest, there is an opening to the side of the path where I spotted what I initially thought may be a white admiral taking up nutrients on the ground. When I stepped closer, I realised I was wrong. He took flight, circled me a few times and landed again. A lesson I was keen to learn quickly from one or two other enthusiasts, is to fight the urge to jump in and get close, as they are particularly flighty when they initially land. After 30 seconds or so, I took some steps closer and he seemed happy for me to get pretty close and take some photos, though unfortunately, he didn’t stick around for any quality shots. He shot up, glided his way along the path, over the trees and out of sight. I stuck around for a while longer, but I saw no return. No complaints, just delighted.

25th June 2020

After getting distracted by a solitary purple hairstreak in the very early morning and failing to get any open wing shots despite the bright sunshine, I started walking through the network of paths, looking deep into the distance for any familiar flight patterns. The number of other enthusiasts was reaching a peak, with around 15 people spread across the forest, either pitched up at familiar locations, or patrolling the rides. One thing which did prick my interest was that no one seemed to have much luck, particularly with lures. The wide variety of chemical concoctions chosen by different enthusiasts raises the question of what works best. While I haven’t seen any published, controlled experiments, there are many suggestions that fox scat and shrimp paste provide some of the best results. Why this is, I’m not sure, however the tendency to favour carnivorous options raises the question of whether there are relationships between wild carnivores and A. iris in suitable habitats on mainland Europe.

Fortunately, after returning to the same location that I had seen my first individual the week before, I spotted another on the ground. I grabbed a few quick photos, but again, they didn’t stick around for long. This individual headed down the path, landing every 20 metres or so in direct sunlight, but never settling for more than 10 seconds. After reaching the shaded stretch of the path, they flew up high towards the canopy and eventually exited the ride.

28th June 2020

My next visit to Chiddingfold forest culminated in the most successful day for encounters. Over the course of 3 hours, I made 5 sightings of at least 3 individuals. The first sighting occurred when I ran into two enthusiasts chatting in the middle of a winding stretch of path, adjacent to a shallow valley. We all seemed to spot the male at the same time, and he landed 20 metres in front of us. One of the enthusiasts approached for a photo and he flew up, circled us and landed at the foot of the other enthusiast. I managed to get some photos as he crept onto the shoe, attempting to take nutrients. After around 2 minutes, he flew up and off, and was not seen again. Unfortunately, neither of the other encounters were quite as entertaining, but still as rewarding.

There are a few larger questions which come to mind when I consider the state of A. iris in the UK. Firstly, what can be done in terms of habitat management to help provide a buffer to the impacts of climate change? What we do know is that with climate change, the higher spring temperatures will encourage earlier emergences, and potentially result in risky additional broods. Secondly, I’m aware that the lack of suitable habitat and connectivity contribute greatly to the restricted distribution of A. iris and many other butterfly species. However, given the reliance on willows as a larval host plant, I would be interested to know whether there are any relationships between unmanaged deer and A. iris distributions. Logic tells me that areas with high populations of unmanaged deer are likely to have increased grazing of willow, and therefore potentially reduce the populations of A. iris. I will save the re-wilding discussion for another day, but the carefully controlled populations of stock at the Knepp estate does provide an interesting opportunity to address this question.

The general pattern I observed was of consistently low numbers of A. iris. As far as I understand, there tends to be a peak in numbers after a few weeks of the first emergence, however the onset of stormy weather with high wind speeds had a particularly devastating impact. Ultimately, the peak never really reached the heights that it typically does. The impacts may be more obvious come next summer, however I will endeavour to spend some time at a local patch during the autumn and spring searching for caterpillars to broaden my understanding of this sensitive species.

[Wurzel]

A really interesting report Max - you seem to have picked up some of the key pointers when it comes to finding His Nibbs However there is a sure fire way that I'm definitely going to try next year - that is to get someone that you know who isn't into butterflies to accompany you as Emperors seem to have a penchant for landing on the deck in front of people that don;t know what they are On a more serious note this year wasn't exactly a vintage one as you mentioned, most probably due to the stormy weather that hit at just the wrong time

Have a goodun and stay safe

Wurzel

[David M]

It's very good to learn about how others go about hunting down butterflies and the strategies they employ, Max.

You certainly put a lot of effort into studying Purple Emperors this year, and you were rewarded better than most of us given how difficult this species has been in 2020.

Your question regarding climate change and how it might affect this species is timely, because up until early June conditions had been abnormally favourable, only for much of the country to endure a dire couple of weeks immediately afterwards. Whether this contributed to low emergence of Emperors I wouldn't like to say, but it's hard to believe that it didn't have an impact on them during the most critical period, i.e. pupation.

[Neil Freeman]

Another interesting report Max, great stuff

Your question regarding climate change and how it might affect this species is timely, because up until early June conditions had been abnormally favourable, only for much of the country to endure a dire couple of weeks immediately afterwards.

Indeed. Around my part of the midlands we had one of the driest springs on record and then we hit mid June then had one of the wettest summers. Definitely a year of two half's here.

Cheers,

Neil.

[Max Anderson]

Brown hairstreak

Over the past few months, I’ve been trawling through the old sightings pages for the Sussex BC website from 2006-2020 to extract any records of brown hairstreak from the county. I wanted to learn what we know about the species within the county and to understand where the gaps in our knowledge are, and to potentially address some of these myself. In the process of doing this, I’ve obtained over 750 records of brown hairstreak adults, eggs and larvae.

At the same time, I have been monitoring a number of sites for eggs to learn more about their habits, and to establish my own baselines from which I, or others, can begin to draw meaningful conclusions in the future.

In Sussex, there are a number of important sites where brown hairstreak have been discovered in the last few years, and the work done by many enthusiasts has been incredibly valuable in improving our understanding of their distribution. In 2010-2011, enthusiasts worked tirelessly and often obsessively, to search for brown hairstreak presence in tetrads (2x2 km grid squares), to establish their distribution across the county. Results showed that around a quarter of the county had brown hairstreak present, with the vast majority located in West Sussex. It was interesting to see that the brown hairstreak had rarely been recorded west of Plumpton, some 30km from the Kent border.

Habitat management for brown hairstreak is a relatively simple principle, maintaining a diversity in age of blackthorn, by cutting back older growth, often in a cutting rotation every 4 years. To some, this can appear to be quite an invasive and damaging process. While I won’t get into a discussion about habitat management, it is an incredibly complex process, which is most often implemented to improve an entire ecosystem, not simply an individual species. I’m in the process of putting together a post about this topic and look forward to delving into this at a greater depth in the near future.

In addition to the desk study, I also ventured out on some egg searches during the winter. I have identified a few local sites, where I’ve found eggs occurring at a wide range of heights. See below for data relating to two of my sites:

As an aside, I would encourage anyone who reports egg counts, to do so as a count per hour. This way, we get an idea of how much effort is required to achieve this count, and which can be compared with other sites, and previous years. Often, when reading through sightings reports, data on egg counts is reported as a total number, which is difficult to use when trying to make meaningful comparisons.

Unfortunately, I am unable to say whether these observations are normal, as I only have one year of data. However, a number of other recorders across the country have also reported an higher proportion of eggs being laid at unusually low and high locations.

Typically, females will favour laying their eggs on south or east facing plants, which are ideally sheltered. Eggs are most often laid on young growth (1-2 year old growth) and usually laid below 1.5m. I have been trying to understand the factors which determine where a female will lay eggs on the foodplant, and have been unable to draw any clear conclusions as of yet. I would be very interested to explore this further, and will take some time to think how this can be achieved in the coming year.

With regards to why there is a difference in the heights at which eggs are typically laid, I predict this may be related to either predation risk or temperature. I will endeavour to make further observations to understand whether there are any benefits associated with eggs being laid at varying heights.

I’m very much looking forward to observing the emerging caterpillars and closely monitoring their development.

Happy new year all!

[Max Anderson]

Over the last few months, as well as chasing brown hairstreak eggs, I've also spent a considerable amount of time searching for black hairstreak (Satyrium pruni) eggs at Ditchling common (Sussex). This was partly because I had become quite adept at spotting brown hairstreak eggs and fancied a challenge, but also to see if I could identify any 'new' locations for the species. I spent around 22 hours searching for eggs over the course of a 3 month period, and yielded a whopping 4 eggs. I was unable to find any eggs in locations outside of their 'known range'. All 4 eggs were laid on a fork of the main stem of blackthorn, and all were over 150cm above the ground. I quickly established a 'rule of thumb', prioritising plants with stems as wide as my own thumb. Three of the eggs were west-facing, one south-west facing, and all were within close proximity to large oaks. Consequently, all eggs were in considerably shaded locations. Most of the reading I have done indicated that the eggs are typically laid in this way.

Egg 1:

Egg 2:

Egg 3:

Egg 3 (contextual):

Egg 4:

I stumbled across an interesting study from Hermann (1996) on the egg laying habits of pruni in Southwest Germany. Some of the results suggested that eggs on Prunus spinosa (blackthorn) are typically laid below 30cm, and generally in areas which maintain high humidity. Conversely, an alternative study sites showed a preference for egg-laying in dry, well-sunlit branches above 150cm. Additionally, two independent observations of egg laying habits are reported, whereby the female enters the blackthorn at a height of around 150-200cm, before travelling down the main stem, to deposit eggs below 30cm. While I dedicated a considerable proportion of my time searching below 30cm, I have yet to find any eggs below 150cm. Caution must be applied to these results, given the difference in habitat conditions between these study sites and those in the UK. Nonetheless, all of these observations hint at a complex set of criteria for optimal egg-laying conditions for pruni, which appears to be particularly sensitive to humidity, shade and potentially predation/parasitism risk.

I would be very interested to hear from others about any searching techniques, observations of egg-laying behaviour or habits of pruni .

[William]

Been enjoying your posts, Max - some fantastic photos and observations!

Seeing your Black Hairstreaks, I thought I'd butt in with my two-penneth. I don't have loads of experience of finding the eggs, so this is based off a small and biased sample, but have looked for them in Bernwood forest from time to time. It's a bit difficult to draw any conclusions as my tally isn't very high (maybe 20 eggs now) and I tend to search in a pretty unsystematic way, a few hours here and there, trying bushes that I like the look of.

At the moment I don't have my notebooks to hand with most of the information, but like you I tend to find eggs on older bushes (trunks 5 or so cm diameter), though not necessarily the thickest stems of said bushes (thumb-width as a minimum sounds right). In contrast though, I have found some of these eggs on the trunks of bushes, and some slightly lower - often (maybe the majority) below 1m, though none yet lower than about 50cm. This may partly reflect the way I search (not pulling down upper branches very often). Some of these eggs have actually been on trunks inside bramble bushes (where bushes grow out of bramble scrub and females must have crawled down the stem). Of the eggs I've found, they almost always seem to be on rougher patches of bark, often under thorns (like in your photos), but sometimes just by themselves on the middle of a stem. One thing I've also found for the first time this winter has been old, hatched shells (from the summer before last), I'm pretty sure they're hatched rather than parasitized as they're all covered in lichens which must take a while to build up. In one case, one of these old shells was right next to fresh eggs from last summer on a bush that I've found eggs on every winter I've checked - quite cool! This bush was a fairly large, isolated bush standing proud of a larger block of scrub and had 2 other old eggs on this winter. There aren't many of this sort of bush in Bernwood, but they do seem to be quite good places to search.

Old egg (top) and new egg (bottom).

This bush had one new egg and 3 old ones this winter.

There's another continental paper on egg-laying from Austria - Kosuch et al (2004) - 'Field observation of eggs of the black hairstreak Satyrium pruni (Linnaeus, 1758) in the southern part of Styria (Austria) (Lepidoptera: Lycaendae [Lycaenidae])' that suggests sunny to semi-shaded, isolated bushes may be good (iirc it was hard to find, but I have a pdf if you want it). They reach similar conclusions to your German one, with an impressive sample of 400 eggs (on Bird Cherry though) and reckon they were finding them every 15-30 minutes. They found that most are laid down near the ground on thick stems. This is rather in contrast to Jeremy Thomas' work I think. They suggest that eggs were probably easier to spot on trunks, and I suppose another explanation may be climate-related, with Black Hairstreaks choosing cooler, shadier situations in warmer climates than they do here (apparently they also aren't really found on dry sites with Blackthorn in Austria preferring the humid ones with bird cherry). This sort of thing has been tentatively suggested for Brown Hairstreak which apparently may lay higher up and in shadier sites further south in Europe, and well-supported for grassland species whose niches can be more obviously related to microclimate.

[Max Anderson]

Thanks for your comments Will. Very useful to hear about your observations and experiences. I appreciate the sample sizes aren't going to be very large, but I think it's a good place to start, particularly given how little we know about some of the habits of this butterfly in the UK.

I do endeavour to remain systematic during my searches, though inevitably, my focus would likely have been biased towards searching thicker trunks, or bushes that look 'just right'. Some interesting comments on finding new eggs near to old ones. I spent some time searching bushes that had eggs on in previous years, given the presence of old markers, but I didn't find any on those this year. I'll keep an eye on the new locations and see what next year brings.

On the Kosuch (2004) paper - I did manage to find a copy of this back in November and put some of it though a translator, though given the focus on Prunus padus , I thought it wouldn't be as relevant. Nonethless, you're right that the results essentially coroborate the findings from the Hermann (1996) paper, and I'm glad you brought it up! I also think you're right about Jeremy Thomas; from what I recall, he suggests that most would be found on one to four year-old branches of Prunus.

You may also be interested to watch a video I came across which also seems to align with the suggested searching critera we've already mentioned - https://www.youtube.com/watch?v=QQ5bQGdLe6w