Ashley Whitlock
Hampshire & IOW Butterflies and Moths
Purple Emperor Assembly Points
A typical pose of a male Purple Emperor on the edge of a Oak leaf. Despite their size being Britain's second largest butterfly, they will stay on their territory spray of leaves on the crown of the oak totally undetected. Even when they fly you need to be in the right position to see their flight away from the tree. This is all dependant on the time in the afternoon and wind direction and where the sun is.
The privilege of going up in a cherry picker to watch how the Purple Emperor performs whilst looking down on them is something I shall never forget. The Males going on patrol up and down the ride seeing the flashing purple on the forewings as the sunlight hit the wings is remarkable.
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The Assembly Point in Havant Thicket which I discovered in the early 2000's, is almost on flat ground but has sloping sides on two sides, one facing west and one facing east, but it's really not very obvious. That's why a good Ordnance Survey map is always good to look at and to study where all the contour lines are. However the site has had some good exchanges between resident males in this 'vista' in the woods. The males like to sit on the Beech trees on the right and the left of the picture dependant on the wind direction and where the sun is at the time.
The Assembly Point in Goose Green in Alice Holt Forest, mainly supported by Oak stands with Sweet Chestnut and small Beech trees, plus there are a few Cherry trees thrown into the mix as well. The tree in the centre a prominent Oak with a Sweet Chestnut understorey is the one in the picture of the high rise at the top of this article. To get good viewings of the activity I usually sit on a chair with a pair of binoculars for at least two hours, as the picture right shows. Alice Holt Forest has at least 5-6 Assembly Points to date. Several of them haven't been used for several years. New ones are being discovered, and temporary ones are used especially during stormy windy weather, but these are normally found in the main rides in more sheltered spots.
This is the main battle ground in Goose Green Inclosure with Large Oaks and with an understory of Sweet Chestnut trees which the males utilise to rest and hold territories. The Oak half-way down the ride also has a male on territory there most years.
Master tree or Assembly areas what’s in a name……………
Master trees can be tricky and many of them can be overlooked, or not recognised as such. This is where homework and good planning come into being. Some Assembly points can be recognised on an ordnance survey map. I.e. contour lines reaching a peak and this where you should aim to plan any investigation. Many trees cannot be seen so well in the summer months with other vegetation and foliage generally obscuring your view. Many Assembly points have been identified outside of a wood and in the winter months when it is a lot clearer to see the trees or area of interest. At a good ‘master tree’ in suitable weather during the ‘peak’ season period which can vary now from mid-late June and early July, it was once in the 1980’s mid-July but because of our summers tending to become warmer, due to global warming this has brought the insect out at least two weeks earlier over the last decade or so…
Favoured assembly areas are occupied every afternoon throughout the flight season though a number of males present and the degree of activity are reduced in extremes of temperature (very cool conditions or very hot >25c) cloudy dull conditions and wind depending on degree of shelter. The presence of clashing, battling, and chasing pairs of males is almost diagnostic. Look for high speed, high level chases. However on windy days this activity is often localised, being concentrated around sheltered bowls close to tree foliage.
These Assembly areas are rarely single large trees but are normally groups of two to ten trees. Occasionally in woods of fairly even canopy height on level ground, males establish individual territories on large stands of up to a hectare or so in size, and make sorties to invade each other’s territories. Many types of broad leafed trees are used for perching, and from these notes of Matthew Oates he says as yet no conifers have been utilised. These pictures prove now that the Purple Emperor certainly does utilise conifer plantations especially in Abbots Wood Inclosure car-park.
Most Assembly areas are on high ground, but on level topography prominent tall trees may be used, at least in sheltered conditions. The butterfly can migrate, or even commute daily, out of level canopy woodland on flat ground to wooded higher ground. Shelter from prevailing winds is essential and is provided by high ground or tall trees to the south and west. Conifer blocks are particularly good for providing this shelter. (Alice Holt Forest being a prime example) Many Assembly areas are along north or east facing woodland edges. These are best found by working outside the wood. Glades or open rides are not necessarily adjacent, which suggests that some/many assembly areas are hidden from view.
You should not go more than 20 minutes without seeing an adult (perhaps 30 minutes) in a rotten season during the period 13:30 -17.00. Forget morning’s stay in bed. More ever you should have several sightings of chasing pairs (mainly fighting males, but also courting pairs) although it is often difficult to see and sex the species, at height and distance. Although in my experience I have always managed to see the female as a much larger of the two sexes, when paired up always leading the way in a slower follow me flight. This often stands out as the females mating flight from the other bish, bash, bosh, flights normally associated with the territory flights, and chases. They are at height difficult to sex as the sexes do vary in size and from a distance are very hard to distinguish. Stay in the same area for at least an hour or so, discard your camera, although it is worth trying to record these events if you have the right lenses and are damn quick…. Also be prepared for neck ache and forsake all other species!
Recording what goes on at an Assembly point is quite time consuming, but very rewarding especially if it is in an area of a lot of 'activity'. No two years are the same, but you can gauge how well the Purple Emperor has done in the season by how much activity happens at certain Assembly Points.
A male on take off from his perch on an Oak leaf, in Goose Green Inclosure doing a random patrol, checking on his territory. I've seen them attack Purple Hairstreaks, Dragonflies, Pigeons, Tits, and even Rooks and other quite large birds. The Chinook Helicopter is sometimes investigated when they fly over from RAF Odiham
Date: 1 July 2014
Weather: Very warm but breezy
Temperature: 70f
Observers: Ashley Whitlock
Southleigh Forest
My second year visiting this site and the site is becoming one of my favourites, after drawing a blank in Creech Wood where it was rather exposed and very breezy, the Oak tree is still there and so are the Emperors. After visiting Creech in the morning and not seeing anything resembling a Purple Emperor I wasn’t hoping for much, however in the afternoon the weather had become much warmer and less cloudy, although it was still rather breezy.
I arrived at 1320 and almost instantly I saw one Emperor doing his normal ‘s’ patrol on top of the of the canopy, it’s just amazing to me how these species manage to find the same site and tree year after year. He settled on the oak tree facing out over the canopy facing north. Because the vista here is very large, it’s quite a task for the male to seek out any further males, as this one was, they have to fly for quite some time around the vista making sure all is clear. When one male seemed to disappear around the back of the oak I noticed a male at the other end of the oak, thinking it couldn’t be the same one in that short space of time?, Then suddenly I saw both of them together, at 1336 one male at one end of the oak and the other patrolling the other end, they both flew towards each other, and then they clashed, chasing each other right over the wood. I thought there were two here, and I was right, and one of the males came back did his usual ‘s’ shaped patrol, and settled down on his perch again.
Two were seen again over the oak, and then again a small skirmish and clash at 1338, a quick chase and then settling back down on his perch again.
I went looking in the other vista where I though there should be another one at least but it was clearly not occupied at the time and was quite breezy at times.
There are good amounts of Sallow in the wood, and things should get more interesting in the next week when the females start to fly.
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The main reject sequence of a female Purple Emperor after a male has pursued her for mating, but she is not receptive. The female will fall or crash into undergrowth or on to the ground, with the male in hot pursuit. Once he has given up trying to mate with her she will rest up awhile to make sure the coast is clear. This behaviour is seen in Goose Green Inclosure and other Assembly areas.
An Assembly Point I identified from outside of a wood in a grassy field, on private land in Hampshire a few years ago. As you can see the rise in the topography is a dead give away, and finding the trees, that the Purple Emperors use.
Sitting in a deckchair looking up at the Assembly point with a good pair of binoculars is the only comfortable way of looking at your quarry. Be prepared to be disappointed by not seeing anything! Sometimes a male Purple Emperor will just sit in his lofty leafy position and not move for many hours, especially if there is no other males which come into his territory.
Master trees were identified in the Victorian times, have become synonymous with Purple Emperors. Here are two Oak trees which just stand alone, close to a ride or a thicket in the woods. The one on the left is at Butterwood where I learnt all about the Purple Emperor and on the right is the large Oak in Bentley Wood at the first crossways from the carpark. Apologies for the photographs taken on print film in the 1980's and have not lasted very well.!
The male will keep coming back to the same spray on the favoured tree, this one is an Oak. And will sit and wait until another male strays into his territory and he then will give chase, which can last several minutes, and they will spiral up into the sky and then split and break off and then they will come back down and settle down on their given perches.
Picture:Philippa Gordon
It cannot be very comfortable trying to perch on a conifer tree, as you can see from this photo the butterfly is certainly very exposed. This site in Abbotts Wood Inclosure is constantly used during the Purple Emperor season, but the butterflies tend to use this site and another not so far away, and combining the two gets quite heated sometimes between rival males who will invade each others territory quite readily. Several of the Conifers are utilised, but if there is a breeze then Oak and Beech which are less exposed are used, although the butterfly is less obvious on these other trees.
This is the only image I've seen in 30 odd years of the male and female rejection at close quarters, the female is on the right and the male is still in hot pursuit. This was taken at Abbotstone Car-park where there is a Assembly Point just off of the main road
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This remarkably intact female was found on the forest floor, and believe me they are not readily that friendly. This was probably in shock after an incident with a male, maybe a mating rejection. Females are normally shy and retiring insects and to come across one like this is quite unusual.
Not all woods I visit have Oak as a predominant tree as Purple Emperor use as its territory tree. Here a male is sitting on a Western Red Cedar tree, and also utilised here is Sitka Spruce, and Hemlock.
Date: 10 July 2011
Weather: Cloudy with short intervals of sunshine nil wind
Temperature: 65f
Recorders: Ashley Whitlock & Matthew Oates
Goose Green Inclosure
Arrived at 1320 met Matthew again and he said he’d seen one male on a very long and undulating flight meandering around, typical of male which is probably on his own. He had said that the males do tend to get to the assembly points at different times especially when there are females around, and different times of the flight season. I didn’t see anything until I moved down to the oak tree halfway down the summit. One male was seen ambling in and around the large oak behind the small beech at the summit at 1330. Suddenly at 1331 there was violence with two males chasing each other, good chase out over the oaks at the back of the summit, and losing sight of them. Then one returns to the Sweet Chestnut tree, and the other one settled on the oak.
Then they went off again, chasing down the way leaves, and then there was a third male seen suddenly there was mayhem, with Emperors coming in from all directions! (3) Were seen together at 1335 and then it was (4) or possibly (5 or 6) as there was two lots of Emperors seen doing battle at different stations, and two were seen just coming in from the east of the summit, over the road. One of the Emperors settled down on the Beech treat the summit. One was noted then off of the oak at the back of the summit, and another off of the beech at the summit, they did not clash, but seemed to be looking for other males.
The weather at this time was warm but cloudy. Matthew had visited Georges glade, and had seen (2) males there as well so there may well have been (8) here, which is a very good number. I looked at the Vista in the car-park and indeed there was a male patrolling the main oaks to the side of the vista, and then I saw another male patrolling in and around the vista at 1355. One of the males proceeded to beat up a Purple Hairstreak, and chased out of his air-space!.
The sun had been out for a few minutes and it was quite warm, and the two in Georges Vista were very active, and there was still a male flying in and around the main oaks at the back of the short beech tree, at the summit. Now there were a lot of black clouds rolling in and the sun had decided to disappear again, so I decided to leave at 1410.
West Harting Down is one of the very few Assembly areas I know on chalk downland, albeit surrounded by beech and conifer woodland. This is what you are looking for though in the distance is Queen Elizabeth Country Park and beyond that you just make out the hills of the Isle of Wight.
The Assembly Point at Southleigh Forest, where there are usually just two males battling it out in the territory 'vista'. Its built on a ridge, and the terrain really does undulate here, giving this area a good arena for these butterflies to do their stuff!
A map sent to me by MRO when we started looking at the Assembly areas in major woods, and trying to discover new areas of territory. This is Botley/Whiteley Pastures, where there are two potential areas, close to high ground in the wood.
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The main ride in Abbotts Wood Inclosure which seriously underlates giving some good height at either end of the Inclosure and several more on the westerly and eastern flanks. As you can see from this picture several quite dominant Oaks can be seen on the skyline and these are used during colder and windier weather as they are more sheltered.
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Most people do not go looking for evidence of Purple Emperors in the Winter or Spring, but woodland has a lot of clues finding the Purple Emperor caterpillar is not easy, and can be quite dangerous having to use step ladders and it takes a lot of time and patience, so in the spring you can find the abundance of sallow the Purple Emperors butterflies food plant as it's one of the first trees to come into 'flower' and the tree can be seen from long distances, (ie binoculars). The topography of a site is easier without all the cumbersome leaves getting in the way and Assembly trees look much more, pronounced against the skyline.