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.
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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.