OK, so its another cool, overcast day here in Hampshire which limits my butterfly outings so here instead is the next instalment into my study of Small Coppers in and around the Broxhead lek.
My previous two reports covered my observations of the population fluctuation and characteristics of the Small Coppers in my area. This is part 3 and will cover their behaviours.
Courtship, mating and mating-rejection tactics
In the courtship the butterflies seem to walk around each other for awhile, typically the male pursuing the female.
- Courting pair
Often courtship is long and involved. I have seen a pair follow each other around for 15 minutes or more, stopping to touch and rub up against each other. One couple went to all this bother for ages and then the male just flew off, not to return. She was just left in the lurch, stood up at the altar as it were. Given that males are always on the look-out for a virgin female, and this obviously was a virgin female showing an interest in him, I cannot understand why he just flew off like this. There was another Small Copper in the vicinity and it could have been a male for him to see off, but I hung around and was sure he did not return to the female, and neither did any other male while I was watching. Maybe it was me taking pictures that put him off!
In the picture below I believe the male is nestling the female from behind. An entry in Hoggers diary shows this too. In this instance the female is receptive but on this occasion I did not witness mating.
- Male "nestling" a female
If you are very lucky you will find a mated pair. I was amazed to see a pair making their first contact, performing a courtship dance, making their initial connection, mating while perched and in flight and the final abrupt disconnection with each flying off in different directions. The whole process took just over 30 minutes. During coitus it appeared that one was tickling the other with its leg, I thought at first that this was done by the male to stimulate ovulation. But now I question this.
Coitus can be a protracted exercise for Small Coppers and one cannot presume it is because it is pleasurable. If it isn't for pleasure then the length of time must be for some other reason and that might simply be that it takes a long while for the male to fertilise all the females eggs. The male needs to know when he has accomplished that effectively. So I thought it may be that there is some chemical signal released onto the surface of the female's body when full fertilisation has been achieved and the male is testing for this with his feet. However, later I witnessed the female also moving her legs to touch the male so now I am not so sure that the male is either stimulating ovulation or testing for a chemical after all.
- Mating pair - wings closed and doing leg-tickling
Hoggers diary shows a female reaching out with her leg in a similar picture to my own here. I took a video and from what I can tell both the female and the male use their hind legs to tickle the other’s body. Because the male stands on his back four legs, he moves his front legs out in front of him to keep balance on the other three when he lifts one of his hind legs to tickle.
It may be that this two-way, leg-tickling is some form of communication going on to do with fertilisation completion and chemical release has nothing to do with it. Butterfly semaphore! Does anyone know?
I saw a TV programme about Painted Lady butterflies which showed precisely the same leg behaviour when they mated too. How many species do this I wonder?
It surprised me how abruptly the mating pair I saw at Broxhead parted company. After 30 minutes connection, disconnection was over in a split-second, just as though suddenly the male got the signal he was waiting for and was off immediately.
- Mating pair - wings open
Males try and mate with any female they can in the time that they are alive so its surprising you see them do this so rarely.
- Mating pair - wings closed
If the female is not interested in a male but she just walks off (as she does while searching for egg-laying spots) rather than flying off he may not let her off the hook so easily but continues to pursue her. Her next tactic in mating rejection might be for her to go into the “Turkey Strut” posture. She raises and drops her forewings and flutters her hind-wings from side to side and up and down in a fast, vibrating motion. One aspect of this is that the back wings are able to lay flat while the front wings are up or ajar, hence giving the impression of a turkey. She does this while walking along in a jerky way, hence the strut part of the expression.
- Female doing the "Turkey Strut"
Hoggers has a much better photo than I do of this – see his diary entry dated Sun May 6th 2018 under page tag [68].
I twice videoed this behaviour. On one occasion she was fluttering all four wings at once for some while; the forewings moving up and down and from side to side at the same time as the hind wings but independently of each other. Plus they were moving at different frequencies to each other AND the frequencies varied during the performance.
In the other video the female then took flight but still appeared to be trying to do the Turkey Strut in flight! A peculiar and not particularly simple manoeuvre.
Vibrating like this will make the actual ability of the male to connect with her that much more demanding so it may have a practical purpose for the female who has no wish to mate.
Another explanation for why the female does the “Turkey Strut” has been suggested by Hoggers and that is she may be wafting a pheromone at him which says “stay away” and when this does not work it might be because she is running out of the chemical scent. Nice idea. The importance of scent in the world of butterflies is probably widely overlooked.
Of course this tactic need not work either and the last resort for the female is to fly out of her tormentors territory altogether. In locations with lots of Small Coppers, females are constantly pestered in this way by all the males who have overlapping territories. Its amazing they find time for nectaring and laying eggs!
Although I cannot be absolutely sure, I think the following picture shows an already mated (gravid) female (farthest left) doing the Turkey Strut to ward off the unwanted sexual advances of a male close behind her while an un-mated female looks on from a distance. If only the male turned around he might find his ideal mate! Of course this is just one of a number of possible interpretations.
Perching and Roosting
At night Small Coppers roost head down on grass and other plant stems with their forewings retracted and closed up. They can also go into this position on cool or breezy days. Not only is this position the best to retain heat and restrict buffeting from the wind but it also means they are camouflaged from predators better. Quite literally they keep a low profile. They can actually look like part of the grass they are perching on. They can often be much further down the stem than the picture below suggests. I once disturbed one that was roosting on a grass stem just millimetres above the ground surface. When that one flew off thinking I was a predator it did a pretty good impression of a yellowing autumnal birch leaf blowing along the ground. It had me fooled for a while. For such a brightly-coloured butterfly it has some very clever camouflage techniques.
- Roosting position
It is well known that during the day, males have regular perch points from which they make sparring and nectaring sorties. I have observed these perch points to be on flowers such as heather or bushes such as bramble or even pebbles lying on the ground. Anywhere where they can get a good all-round view. Of course females are also on watch for eligible males.
Pebbles can be useful to any Small Copper wishing to recharge its batteries because not only can it bask in the direct radiance from the sun but also gain borrowed energy from the heat re-radiated from below because the stone has also warmed up in the sun. This one in the picture below has decided a pine cone is a choice perch. It never occurred to me at the time to check if he might be licking pine sap from it but he probably wasn’t.
Sparring fights and intimidation strategies over territories
I have read that not only do males perform fighting flights over territories but also when tired, they intimidate one another as they perch. Below is a possible example of what might be intimidating behaviour between two males although I have to say the one in front has a fat-ish body and may be a female. It could just as easily be a courtship dance.
After a night in the second week of October 2016 (the 11th) when the temperature crashed to below 4 degrees it did not warm up above 10 degrees until 11 am. This saw the demise of all the older, tatty Small Coppers at Broxhead and only three were left flying in the lek, all of them relatively fresh and strong and one of them a male. When disturbed he would fly a long way and if disturbed again he would do the same again and he was never once challenged by another male because there were no others. He was “King of the Lek”. My focus all the while has been on lek behaviours but what I think I was seeing here is what is probably the more usual behaviour when individuals live alone outside of leks. Then there are always fewer males to spar with and also fewer females to mate with, so although the lek is a tiring place for a Small Copper to exist in, the benefits far outweigh the disadvantages of a more solitary existence. In a lek there are lots of small overlapping male territories and lots of females flying through them. Outside of the lek the male territories are potentially much larger and less likely to overlap but they must spend more time patrolling and waiting for a female to pass through.
I have subsequently witnessed the mid-way situation, neither lek nor solitary existence of a small group of four males along a grassy path on Odiham Common. Here what they seem to do is work out their own territories so that they do not overlap and only occassionally then need to fight to protect the borders. Such fighting is quite rare in this instance. The distance for each territory could be paced out along the path. There was about 15 paces between each perched individual in this instance.
Unlike in the Broxhead lek where the territories overlap and there are constant disputes between males, all here was more usually calm between neighbouring males while they basked in the sun waiting for a female to pass through. Unfortunately while I was there no female passed through so I could not see if the dynamic changed when a potential mate entered the scene.
Egg-laying
After mating the female will fly off and walk about on the ground searching for sorrel patches on which to lay her eggs. It appears she favours smaller, younger sorrel in areas with close-cropped grass just like the one pictured below. She will use her antennae and also her front legs to feel her way and when she finds a good spot she will bring her abdomen forward underneath her in the usual butterfly egg-laying posture, in this way she positions it how she wants. I videoed this behaviour and was surprised at her precision.
You can see the abdomen being thrust forward in this shot below but with her forewings retracted I have seen a female push her abdomen much further forward than this.
- Egglaying
It is surprising how much time and effort a female will go to, creeping around in the undergrowth, testing and searching for what she considers to be the very best locations for her offspring. I followed one for 30 minutes doing this.
The eggs are tiny, pinhead-sized golf-balls needing a field-glass to see properly. With help from Pauline who found this egg below I was able to get a rather shaky picture. Notice the egg is laid directly on a leaf of sorrel here. This need not always be the case but it will always be near this plant at Broxhead.
- Egg
When the egg hatches it is as though a hole is punched right through it. The larva does not eat the egg but just leaves it behind still attached to the leaf. This picture below shows a hatched egg.
- Hatched egg
The larvae develop through a number of instars. This (again not very good) picture shows an early instar. Pauline as usual has done a better job than me recording these images so please go to her diary-pages.
- Larva
My books tell me that when they are very tiny they eat away the sorrel leaf from below which produces transparent white lines in the leaf without actually cutting right through. Only later when they are in their final instars might they create damage that penetrates right through the leaf. There can be as many as 5 instars, especially in those that overwinter. The overwintering ones attach themselves to a sorrel leaf or leaf stem using silk in order to survive the ravages of winter. Later, a green caterpillar with purple stripes down its sides develops to a size of about 16 mm. They hide underneath sorrel leaves in June, August and October. The last brood's progeny overwinter in one of its instar forms from October to March.
This medium term instar I came across is showing the first vestige of a stripe.
- Medium-term instar with stripe
They may be this colour for camouflage against the sorrel leaves because as the leaves start to go over they are often green and red in the same hues as the larva.
- Sorrel leaf turning red
The Stalk Dance – a bit of a mystery
Here is a behaviour I haven't quite figured out yet. The Small Copper perches on the top of a stalk, then moves around so that it faces downward as if to roost but then walks down the stalk, tapping the stalk with one of its front feet as it goes. When it gets part of the way down it flies off abruptly and then perches on a neighbouring stalk. The first one I saw do this did so repeatedly many times while I watched. Sometimes on a long grass blade, sometimes on a stalk or some other vertical twig, sometimes on a fern spine and once on a bramble stem. It would walk vertically down or horizontally. Hoggers says he has seen one walk up a stem in such a fashion!
The one shown below was on its own as far as I could tell.
- The Stalk Dance
The Hoggers diary mentions this behaviour that he calls the “Stalk Dance” as being predominantly a male activity and is more frequent than you might imagine, its just I had never seen it before I took a video of this one – the picture is a still shot from that video.
The Hoggers diary refers to page 106 of Thomas and Lewington which states, in relation to male Small Coppers : "It is sometimes said that he marks his territory with scent." The book does not expand on this so we cannot know whether it is correct in its presumption that scenting is taking place – especially now we think that some females might also perform this act.
Another experience reported on this forum is that one individual tapped blackberries that he walked over!
So why might they do it? Here is a recap of some ideas put forward by others on this forum. None have been proven unfortunately.
Option 1: Testing for females (Assessing territory viability)
It may be a way of determining if a female has visited his patch in the recent past with an intention to lay eggs. Perhaps he is trying to establish how many mated females are laying eggs in his territory and whether or not the offspring are likely to be his. Of course if this is the reason one has to ask why he is doing this on the stalks and not on the leaves of the sorrel which after all, is where the females are more likely to leave their signature. This assumes that there are receptors on the feet of this species of butterfly capable of testing for female presence. It is known some species such as Red Admirals have foot sensors which can pick up sugary substances so it would not be unheard of for this to be true also for Small Coppers.
Option 2: Testing for Sorrel (Improving mate-finding efficiency)
It could be that the male is testing pieces of foliage to see if it's sorrel or not to gauge how popular his patch is to any prospective partner wishing to lay eggs. If he discovers it isn't a good territory he might decide to muscle in on some other male's territory. Until recently I was under the impression that the butterfly does not walk all the way to the bottom of the stalk. Sorrel blooms spring along the stem down to about a third of the stalk. If you are testing a plant to see if its sorrel (without actually looking at it) and have not found evidence on the stem of sorrel buds, flowers or seeds on the top third by touch, there is no point in testing lower down than that. It could mean that the male is testing to find sorrel so as to gain a mental picture of all the prime sorrel in his territory and he does this in order to increase his chances of encountering a freshly emerged virgin female. If he knows where all the sorrel is, he can patrol just those areas where he knows it is growing in order to reduce the flying effort to search for virgins in his domain as they emerge. He will also get to them quicker for mating than other males outside his territory can. He may even shift his master perch point to enable greater efficiency in female-finding. I now have two issues with this. One is that Small Coppers have eyes and should be able to see a plant so why would they need to use touch? But can they see the plant well enough? If you stand perfectly still next to a Small Copper it will not spook. This is true of most butterflies I think. If you move in its vicinity it knows you are there and will fly off. Many male butterflies use scent to attract females in the first instance, suggesting that at the very least the females cannot see them until they get close. It may well be butterflies such as Small Coppers cannot see static objects very well at distance, instead they may only perceive movement, colour and smell. I once witnessed a Holly Blue circling round and round, settling for a moment and then doing the same again and again in ever decreasing circles until it finally landed on some fresh dog poo beside a path and started taking salts from it. It clearly could not see this non-moving object clearly until it got close and seemed to be relying totally on its scent perception until the final landing! Of course they must be able to see static objects that are close to them otherwise they would never be able to perch. However issue 2 was shown by Hoggers quite recently when he photographed one walking all the way to the bottom of the stem. I also saw one individual do it on Sheep's Sorrel a few times. This sorrel had gone over but still retained its fruits. The butterfly in this instance did not stop when the fruits ended but continued to work it's way much further down the stem than would seem necessary. This same butterfly was also doing it short distances on a fern leaf almost laterally and tried to do it on a grass stem but it bent over too much so he flew on. All this probably overturns the hypothesis that it is testing to find sorrel with its feet. It would know pretty soon by walking over the top third so would not need to progress further. Also why would it do it on a large bramble branch for example. Surely as soon as it perched on it, it would know it was not sorrel and so would not need to do any walking and tapping.
Option 3: Signposting a territory (Improving mate-finding effectiveness)
It could be a way of marking out a territory. The foot-tapping may be a means by which a male could deposit a scent on these stalks. An investigator on this forum (sorry I cannot remember who) who followed a particular male Small Copper around for over an hour discovered that the Stalk Dance is a regular part of its daily life, no less important than sparring, courting, sunbathing and nectaring and it shares its time amongst these behaviours. The investigator also noted that the Stalk Dances were done from a few feet to anything up to 40 feet away from its master perch point. This would seem pointless in a lek where territories are determined by sparring and may explain why I have only seen it well outside of lek situations and only once on the edge of the Broxhead lek. In a non-lek situation, the male has to broadcast his presence to any passing female and so he may leave a scent trail on a number of stalks leading toward his master perch point for her to follow. Observers have written that the flight between Stalk Dances is lazy, like it is for nectaring, rather than as it is for sparring or the pursuit of females so it is a relatively relaxing passtime for the butterfly. Another observer noted when one male took over the territory of another male, he would spend quite a lot of his time doing Stalk Dances. It does indeed appear this behaviour is part of the quest to improve the chances of finding a mate but how exactly it achieves that aim is still a mystery although scenting any stalk in this way to act as guideposts for females (this option) is a favourite of mine. Bugboy in one of his posts, concurs and adds they may be displaying UV patterns on their wings we cannot see and I think this is very likely but does not explain the foot-tapping.
Although it is said it is mostly males that do this, Hoggers says it is not exclusively males. In fact I thought the video I took, from which the still is shown above, was that of a female but I have said before that I still sometimes have difficulty identifying gender in Small Coppers. However, if females do this as well as males that brings doubt on all these interpretations.
I have already mentioned it is a feature of the Lycaenidae family of butterflies, of which the Small Copper is one, where the male only uses its rear four legs on which to stand whereas the female uses all six. The books I have read suggest the front legs are not used and are vestigial but that is clearly not the case with the male Small Copper. Instead they appear to have become adapted specifically for this tapping purpose, whatever that is for.
If that is the case, all butterflies that only use their rear four legs to perch may use their front legs for specialised purposes: that is all Lycaenidea males (Hairstreaks, Blues, Coppers and The Duke of Burgundy) and both the males and females of the Nymphalidae family (The Fritillaries, Browns and large butterflies such as the Painted Lady, Purple Emperor, Peacock and Red Admirals etc). This is definitely true for Silver-studded Blues for example where I have seen a male use his front legs to hold onto a female and fight off unwanted intrusions of other males while he is mating. They are used more like arms than legs in this instance.
Behavioural Shifts
At the end of the fourth brood flying season at Broxhead in 2016 I saw no evidence of males sparring, instead rather a lot of females laying eggs instead.
There were only a couple of heather patches left in bloom in the Broxhead lek by October 2nd. Four Small Coppers were nectaring on one of them and two on the other. These last heather patches were only about 1 foot in diameter each and so the butterflies were falling over themselves to get at them but the amount of fighting was greatly diminished, almost to zero, perhaps because they were all females who were sharing a territory rather than fighting over one.
The ones I saw at that time were starting to switch from nectaring on the heather which was in final decline, to the fresh Autumn Hawkbit and the remaining Ragwort which enabled the extension of fourth brood Copper activities at Broxhead even further into October.
- On Autumn Hawkbit
Note that the very late flowering garden-escape asters on the car-park verge beside the Victorian church on Kingsley Common attracted one Small Copper until the end of the second week of October in 2016! She was there on and off for some days. There are small amounts of Sorrel, Sheep’s Sorrel and Dock here, so she had a choice of larval food plants to lay eggs on.
- On Aster
This is one of only two places on Kingsley Common where I have seen spring-time individuals and that is because unlike the main part of the common which is predominantly heathland, this fringe area has spring-flowering plants.
Well that is the end of part 3 of my study into Small Coppers. Behaviours of all butterflies are interesting but Small Coppers for me take it one step further.
Part 4 is the final part and will cover the Broxhead flora in a little more detail because it is the plants that make this habitat so enticing for the Small Copper.
