Study into the Small Coppers of NE Hants and its border with Surrey
This is not a scientific paper. I am not a butterfly expert. I want to underline that from the outset. I am an interested and sometimes intrigued amateur. Intrigued because this little butterfly has some surprises up its sleeve as I am sure you are aware if you have read Hoggars diary on this forum.
I shall from time to time be referring to Hoggars diary because of his fascination with the species and the fact that he is lucky enough to live close to one of the largest Small Copper populations in the UK (arguably the largest of all). I have not sought his permission beforehand – I hope you are OK with that, Hoggars if you are reading this.
This is a report on an observational study I have made of this species in my own area over the last two years and is not complete because I will continue to study the Small Copper throughout 2018 as well. The reason why I am able to do this is because on my doorstep (well within a radius of a few miles anyway) there is a network of lowland heaths and grassy commons which harbour good numbers of this species. In particular, from summer onwards they inhabit a group of heathlands which can be considered continuous, these are Broxhead, Kingsley, Sleaford and Shortheath and form the main study area. However there is a good-sized lek in the reserve at Broxhead and my study centres there.
I am going to split my report into parts that I shall post separately and they will cover all sorts of things such as population, abberation, behaviour, habitat, etc.
First some book data to set the scene.
Flight Periods
All May, June wks 1,2. All July, August and September, October wks 1,2,3. There are usually three broods per year but as these dates suggest, the latter two broods can overlap. On very good years there might even be a fourth brood overlapping the third which takes them well into October.
Primary Habitat
It likes dry grassland, meadow, grassy heath and shingle coast.
Larval Food Plant
Common and Sheep's Sorrel, and to a lesser extent Dock.
Central study area
Broxhead, along the sandy path of the southern section of the reserve that runs down to the sheep field where there is a fair-size lek in a sheltered enclave.
![PICT0917.JPG (1.66 MiB) Viewed 27675 times Part of the Broxhead Small Copper lek](./files/thumb_16593_700e86117503875536fe6f20bbad1fb9)
- Part of the Broxhead Small Copper lek
The habitat of the brood at Broxhead is grass intermixed with heather and sorrel banked with scrub containing plenty of bramble and some fern on a very sandy soil. The area is dotted with high gorse and low trees such as young oak, birch and elder but the butterflies stick mainly to the open ground near the sandy path toward the bottom of the hill where it meets open fields normally populated by a flock of sheep. The area coincides with a rabbit warren. The picture above shows part of the location where the sorrel grows giving the ground a rust-red wash in late spring/early summer.
It is in late August and all of September which sees the brood at its best. The sheep's sorrel flowers have died back by this time though so you cannot see them anymore but the heather is out in full and this attracts the nectaring butterflies. On very sunny days in early September its perfume fills the air while you watch the butterflies whirling and chasing about. The males are very territorial and even chase other butterflies away, for example the Brown Argus which also has a small brood here at this time. On one occasion I witnessed one Small Copper chasing off a Red Admiral successfully. They are feisty little creatures. Another time I stood in the centre of the grassy open lekking area to have at least six Small Copper and two Brown Argus all circling around me at once.
There are, relatively speaking, fewer Small Coppers to be seen elsewhere on the reserve and I think this is because the areas that do have them also harbour rabbits. The rabbits chew away and keep the scrub and heather down and also keep the grass low. This makes an attractive habitat for the sorrel to grow and this is just what the larvae of this little butterfly need to sustain them.
To put my study area into context here is a list of the sites I have found in NE Hants and its border with Surrey.
1. Kingsley Common, anywhere where heather and grass meet. There is also a spring brood here but in the main at this time of year they hug the area behind the houses and in front of the church as there are more nectaring plants there such as stitchwort and white dead nettle.
2. Shortheath, around the Bronze Age Barrow and with a lek to its east. Can also occur in and around the grassy plat in the reserve to the west, closest to the village.
3. Frensham Little Pond, on the right-hand hill flank near the first car park if driving from Frensham.
4. Woolmer, beside the sandy hillock behind the pond (but this is MOD land with extremely tight opening times).
5. Folly Hill, dotted about the reserve away from the pond.
6. Longmoor, the heathland paths parallel to the main track between the car park and the first crossing.
7. Frensham Big Pond, either side of the main car park.
8. Thursley anywhere on the dry heath away from the bog. Also the MOD tract of heath down a dirt lane on the opposite side of the road to the main reserve. There is a car park at its end and Small Coppers can be found in the grassier areas near this.
9. Sleaford Heath, could be anywhere but its a very small area.
10. Binswood, beside the meadow.
11. Noar Hill, typically in the central pits of the reserve.
12. Ludshott Common. Surprisingly for such a large reserve there are few parts that have the grass/heather/sorrel combination but I did find one Small Copper here so there must be others.
![Small Copper on aster in October (13).JPG (4.83 MiB) Viewed 27675 times In front of Kingsley church in October 2016](./files/thumb_16593_fce0d77a0ca6a7eb3a4917017aa1d0bd)
- In front of Kingsley church in October 2016
Small Copper Survey
Part 1 of my report is going to focus on the population numbers. I would argue this is the most boring bit to read about but it was not the most boring bit to research as it enabled me to make comparisons between locations and ponder the reasons why different populations exhibited subtly different behaviours.
Lets start therefore with some data I have collected so far in the form of the spreadsheet attached.
This table attempts to show results without double counting. For example the repeated values of 9 recorded at Broxhead on the 28th and 29th of September are of different individuals, they are not the same count of the same butterflies in the same place counted twice. I visited entirely different parts of the reserve each day and the fact that the total was 9 each time is a co-incidence. Equally I counted 7 at Shortheath on October 5th but have not included them for fear of double-counting those I saw there on September 25th, because I went to precisely the same part of the reserve on that occasion. I was still seeing Small Coppers at Broxhead on 15th October 2016 but guessed these were individuals already flying on 30th September even though they were mostly in very good condition, bright colours with no nicks or tatty edges.
In locations where there are a lot of Small Coppers, investigation has shown that the end-of season decline falls off gradually as per the chart attached below.
That is, if there were, lets say, 40 at peak, then during decline there would be 20 after a given time period, then 10 after an equal period, then 5, then 3, then 1 and finally none. Given an individual in a brood can live for up to three weeks, averaging around 2 weeks, these time periods can be anything between 1 and 3 days. In 2016 it was 3 days. Of course this natural fall-off is largely dependent on clement weather conditions throughout this time. If there was a sudden cold snap or if torrential rain occurred for a few consecutive days, the fall-off would be more abrupt.
What follows are the more specific results from a survey of numbers of Small Copper at the Broxhead Lek only. See attached chart below.
It seems that there was a fast ramp-up of the 3rd brood from early September with a gradual decline of the 4th brood into mid October. The weather across this entire period was fairly good and quite even although there was of course a slow natural decline in temperature, this being Autumn. Some of the nights toward the end fell to 5 degrees centigrade but the daytime temperatures were usually between 14 to 19 degrees with many, long sunny spells. There were no truly bad windy days and never any long runs of days of rain here. Even on days when the ambient air temperature never increased beyond 15 degrees, at the Broxhead Lek on sunny days, being sheltered on all sides, direct sunlight brought the ground temperature microclimate on the valley bottom closer to 19 degrees. For this reason there were more Small Coppers in the lowest parts of the valley than the higher parts. They only moved to the higher parts if the nectaring plants were available up there when they ceased elsewhere. For example there came a time toward the end of the study period when one of the last blooming bell heather clumps could be found on the ridge when almost all the rest in the lek had gone-over. It was only then that I started to find a few Small Coppers on or near the heather on the ridge.
The red bars on the chart are the actual numbers seen on the days the numbers were surveyed, the blue curve estimates the rate of increase and decline based on the actuals.
The survey was from the 8th September to the 15th October 2016. All these figures were taken between 10 am to 1 pm on the survey days. If one visited before 10 am usually the Small Coppers would be hiding themselves away in shrubs and low in grasses because the temperature was too cold for them at that time. If you visited after 3 pm the lower sun at this time of year with the ridge on the west side in the way caused a larger shadow across most of the valley so even though the air temperature could be higher at that time of day, there were fewer opportunities for the butterflies to bask in the sun, so again they hid away, being reluctant to expend energy in flying when there were few blooming plants from which to gain nectar AND little direct sunlight to replenish their energy needs.
A bit of recent history from the 2015 Hampshire & Isle of Wight Butterfly Report now. It does not mention Broxhead as a recorded site. In 2015 the only recorded site in Hampshire that had Small Coppers in double figures was Keyhaven on 15th May, totalling 24 in one day. It appears that the autumn numbers only increase during “Indian Summers”. 2016 certainly fell into this category, at least for Southern Britain with hottest temperatures on record for September. Therefore this survey may have been anomalous for its great numbers over an extended period so late in the year. The Broxhead reserve as a whole peaked at a count of 24 between September 8th and 11th.
There were still 24 across the whole Broxhead reserve from September 28th to October 1st but the profile had changed, they increased in some areas and declined in others so although the number was 24, they were largely different individuals and it is just a coincidence that they totalled 24 in both periods.
Also there was a peak at adjacent Kingsley Common of 29 around September 29th and taken together (you can walk from the edge of the Broxhead Reserve to the edge of Kingsley Common in a few minutes) thats 53 at peak.
These results are quite remarkable for Hampshire. Other locations in Hampshire usually record Small Coppers in singletons or less often in twos and threes. There was only one site better than this in the official 2015 report for Hampshire and you had to cross the Solent for that. In 2015 there were 55 at Whippenham Fields on the Isle of Wight. It must be said though that the IOW site had a count of 351 across the whole year of 2015, not something that could ever occur at Broxhead and Kingsley for lack of nectaring plants earlier in the year (all the heathers flower in the summer and there are few other plant species to take their place earlier than this). The official 2015 report calls Whippenham Fields a “star” location for Small Copper but I would suggest that in 2016 at least, Broxhead & Kingsley was no lesser a location later in the season.
After my initial 2016 numbers count it subsequently come to my attention that an area of the Broxhead reserve that I did not visit in 2016 because the entrance path was overgrown by ferns was visited by someone else who reports he saw upwards of 200 Small Coppers there. I cannot myself vouch for this but if true, that would make the Small Copper count for the whole of Broxhead, Sleaford and Kingsley, an area of heathland we can consider to be contiguous, to be greater than that at Whippenham Fields! At least in 2016.
Unfortunatley 2017 was no so good for the Small Copper at Broxhead or Kingsley so when I visited this new Broxhead location in the same year it did not yield anywhere near 200 individuals, more like a dozen or so instead. Nevertheless although it is difficult to access for humans, the Small Copper does appear to like it there too.
Because of the notability of the Small Copper in Hampshire I decided to extend my survey to cover a period of 12 months. Most surveys I do cover a whole year but in 2016 my count of the Small Copper started mid-year, so I just completed the 12 month period by wrapping round into spring and early summer of the following year. All the data is in the spreadsheet attached above.
There were no great surprises I suppose. The numbers at all surveyed locations were low but consistent. I guess my only finding was that there were a fair number on Odiham Common in 2017. I found this site for the first time in 2017 and visited repeatedly because of the White Letter Hairstreaks there but in the places where the council had cut the grass low so that people could walk across the otherwise tall grassland meadows they had, perhaps inadvertently created the right habitat for Small Coppers. Without actually searching for them, I came across 4 in the time period surveyed - but outside these dates and inside the White Letter Hairstreak flying period there were more Small Coppers that I have not accounted for in my survey. I think they must like the dock here as their food plant because I did not find their preferred sorrel.
There were sufficient males along the “Elm Walk” on Odiham Common in mid-July 2017 to exhibit some of the lek behaviours I have become accustomed to at Broxhead although I would not class this site as a lek per se as their territories align along the path rather than exist in an “area”. It reminded me more of the situation you find Red Admirals in along many a woodland ride at Alice Holt. You could almost pace-out individual territories of male Small Coppers along the Elm Walk. Something like 15 paces or so for each one.
Now all of September and the beginning of October 2016 was remarkable for a long heatwave, a veritable Indian Summer as I have said, but August 2017 was wet, cold and windy, and the start of September was very variable with frequent thunderstorms and higher than average winds, so I though I would make a comparison.
The first two observation days saw a drop of around 1/3 on the same period the previous year. Indeed I went to the Broxhead lek twice not shown on the spreadsheet because it was devoid of Small Coppers. (I guess I should have recorded these entries on my spreadsheet with zeros – but as I said at the top of this post – I am an amateur!) The visit on August 26 also yielded two Brown Argus in exactly the same spot in the lek as last year when I saw six in early September but by the time the storms at the end of August finished, the Brown Argus had been wiped out. A far cry from the previous year. The observation for September 2017 was on the first warm, sunny day for a week but hides the fact that there were only 3 Small Coppers in the lek and two of these were at its bottom extreme, the area most secluded from winds. The other seven all came from the Broxhead area mentioned earlier that I suspect the unconfirmed sighting of 200 Small Coppers was witnessed by an individual I do not know personally. In 2016 I tried and failed to get to it so all my Small Copper records in that year exclude this area, thus the figure of 10 this year on this date being almost the same as it was last year on Sep 9th cannot be taken at face value.
The weather had not improved into the middle of September. I wanted to monitor the Broxhead lek in particular because in 2016 I spoke to others about this location, so the lek got a bit of trampling underfoot (not least by me). I needed to see if it effected the population of Small Coppers by comparing it to other known sites, for example neighbouring Kingsley Common and Shortheath which suffered the same weather conditions but not the trampling effect. I am pleased to say that I am pretty sure the crash in numbers is due to the very inclement weather. I visited Kingsley Common on 12th September 2017 and only found three Small Coppers, 1/10th of the number around this time the previous year. All of them were far flung from each other and all in the most sheltered locations possible. The heather, both ling and bell had mostly gone over by that time so there was little opportunity for nectaring out on the heath. This explains why they were so far flung from each other as they hung around the last few remaining heather blooms and these too were far flung from each other. At Shortheath it was the same story. On 19th September 2017 I found only 1 in the lek there and none elsewhere. This is 1/3 the number seen the previous year on September 14th 2016. After visiting Broxhead, Kingsley and Shortheath in 2017 what struck me the most was how little Bell Heather had bloomed. This may have been critical as the Small Copper favours this plant to nectar from in late summer.
This ends part 1 of my Small Copper Report – as you can see its a bit of a marathon but please stick with it because it gets more interesting when I start to talk about behaviours. Honest.