Posted 1st Jun 2013
To celebrate National Butterfly Education and Awareness Day, LandLove's Natalie Mason visited Tropical Wings Zoo in Essex to meet with entomologist Tony Wren. Tropical Wings have recently formed a conservation partnership with the Essex Wildlife Trust to reintroduce extinct British butterfly species into the wild. We find out more about this incredible programme and our native British butterflies
Why did you decide to partner with The Essex Wildlife Trust to reintroduce British butterfly species?
British butterflies have been going through a terrible decline for decades now for many different reasons, some of which aren't known. As they're not always known it's a case of doing as much as possible to find out, to see whether it might be farming practices or chemical sprays, the general weather or climate, we just want to help the troubled species and try to get the numbers back up again. If the land isn't managed correctly and there's a bad year then a butterfly can be lost from an area completely and that's why we've got involved. As a zoo, Tropical Wings needs to be actively involved with conservation programmes, that's part of every zoo's licence. We really wanted to get involved with local projects and about six or seven years ago the Essex Wildlife Trust approached us on behalf of the Essex Biodiversity Committee, asking us to get involved in rearing the purple emperor butterfly. We set up a polytunnel and then for about four or five years we acquired the livestock from other breeders, reared the butterflies through and then released them onto a site which was at the time secret. Each year we just had to cross our fingers hoping that they would breed. On the last year of introductions there were more seen than released, so we assumed that they were breeding, then for the past three years we haven't released any and they've still been seen every year. We can now sit back and hopefully watch the purple emperor butterfly continue to increase back into that area, which is Marks Hall Gardens and Arboretum in Coggeshall.
Is the purple emperor a British species?
It is a British species and was present in those woods up until the 1950s, then the land started to be managed differently - it used to be coppiced, trees were cut down on rotation and that gave the woodland complex the right kind of structure for the purple emperor butterfly - as soon as that management stopped, even though the woodland was left to mature and grow, you haven't got the right kind of structure or proper management and different trees start to die out. When traditional land management started again it was felt suitable to reintroduce them. It's a massive project and not everyone agrees with it, but if we just sit back and let nature take its course you're effectively going to watch species die out. We've upset the balance so it's our duty to put it right and maybe get those butterflies back. Sometimes, simply by managing the land properly, butterflies will find a way back in. Some move around enough to survive but species like the purple emperor butterfly don't, they're territorial butterflies that seldom fly far from where they emerge, so if the conditions aren't right then they just die out.
That was success number one, we've also introduced with great success the silver-washed fritillary back into the same woods and this year we are starting on the dingy skipper, a little red-brown butterfly that is extinct from Essex, and we're hoping to possibly bring back the Duke of Burgundy.
Why are there some butterflies in Essex that aren't seen anywhere else?
Generally speaking it's down to the way the land was managed for hundreds, if not thousands of years. When woodlands were cut down and areas of grassland and heathland opened up, butterflies that were probably hanging on in tiny little pockets of clearings were then able to spread over the open areas. That explains why there are local variations and as Essex doesn't have many huge expanses of woodland the purple emperor butterfly was lost. The other reason some butterflies are in different regions is climate. It's colder up north, it's warmer down south and some butterflies cope better in the heat and some cope better in the cold. For example the comma butterfly, which is a nice little butterfly that hibernates through the winter so it's often one of the first butterflies to be seen, is traditionally a southern butterfly from warm climates in Europe. It was very southern in its range in the UK but over the last 20-30 years it is actually pushing further and further north and that's probably because it has done so well. Its food plant is nettles and there's no shortage of nettles, and it will breed in gardens, parks, farmland and hedgerows, so as long as the food is there it's happy to spread. Up north you've got butterflies like the northern brown argus and the mountain winglet and you'll find that they're very dark butterflies, quite hairy and a lot of them are getting about by literally walking through the grassland as it's simply too hot for them further south.
So are all of the butterflies we see in our gardens British species or are some of them migrant species?
Most will be British and will complete their entire lifecycle local to where they are seen, but we do have common migrants. The red admiral butterfly, which most people would recognise as it is predominantly black with an orange or red band and black and white tips to the wings, originates in North Africa and southern Europe and pretty much dies out in the UK. Very occasionally you might get the odd one that survives but generally speaking they head south to breed during our winter and then head back north again in spring.
How do they make their way here?
Some butterflies may weigh as much as a rose petal but they can fly a thousand miles no problem. They pick the wind currents and some fly high, some fly low. Species like the red admiral butterfly have arrived in such huge numbers that it's like a black cloud coming across the English Channel, then they'll hit land and find whatever flowers are available to feed on the nectar. Then, they'll start moving north, all the time laying eggs that then turn into caterpillars that will eat plants like thistles and nettles and they'll just keep moving north. So a butterfly that starts its life in Morocco, two generations later it will be flying over the Shetlands.
How long do butterflies live?
Most butterflies lives are relatively short, so you're looking at between a week to two weeks, but some can live longer. Flying quickly as they do everyday, around 15mph or so, they can cover a lot of ground. They can withstand an awful lot, they're tougher creatures than they look.
Are there many British species left in the UK?
Considering there are maybe 24,000 species in the world, we've got a measly 60 species in the UK and a good proportion of those are at real risk of being lost simply because they are so specialist. Many species of butterfly require such specialist conditions that they just simply can't leave. They won't even fly 100 metres, they will just stay on one patch of grass and between two hedgerows or on a grassy verge along the roadside and won't move. So if conditions change that colony will be lost.
Is there anything we can do to keep British butterflies thriving and attract them to our garden?
Planting the right plants will help a good number of butterflies, there's no doubt. Native flowers are always best if people have got an area of their garden that they could devote to letting grow wild. I'm not just talking pretty flowers, sometimes we're talking nettles, thistles, grasses and probably all the things that most people would want to pull up. But, these are food plants to a lot of what are currently our most common butterflies. A lot of the specialist butterflies aren't just going to turn up in your garden if you've planted the right things, you need to be near an existing colony for that to work. So possibly getting involved with your local Wildlife Trust, who rely on volunteers to help manage land for butterflies, is a good thing to do. Just try and understand what is good for the butterflies and what isn't - using pesticides on flowers might keep the flowers looking nice but you're going to end up killing the caterpillars, and it's not just pretty flowers that keep the butterflies going, they need the plants for the caterpillars to live on. If you find a caterpillar in your garden, before spraying it with something try and find out what it is. It could be an uncommon moth or an uncommon butterfly so maybe put up with a few more holes in the leaves. It's very rare for caterpillars to completely devastate a garden, you might have to sacrifice a plant every now and again, but obviously it's a real benefit. A lot of people don't realise that we rely on pollinating insects for our fruit. cereals and crops, and a lot of moths and butterflies are pollinating as they go. If we're kind to them then we're benefiting ourselves.
You can manage caterpillars. If you've got a row of cabbages then maybe let one take a bashing - move the caterpillars onto one rather than spraying the lot. We've got a little allotment patch here at Tropical Wings and it can be very frustrating to grow a whole line of something which is then going to get demolished. So the plan this year is to actually give caterpillars a patch just for them, to attract them away from the one we want to keep. Most people if you've got any kind of land, whether it's a garden or even just a window box, there's something you can do to help butterflies. If you leave one little patch of nettles in a sunny part of the garden then there's at least four species of British butterfly that could lay their eggs on it.
Could you have a wildflower patch if you were concerned about it taking over the garden?
Yes wildflowers, but even grass is important to a lot of butterflies. There is a butterfly doing rather well in south Essex called a marbled white butterfly, it's like a black and white checkerboard, an absolutely beautiful butterfly that just needs grass to lay its eggs on. If people were able to leave a sizeable patch in the garden with a few wildflowers you'll be amazed at what turns up.
Is weather a big part of butterflies' survival?
Butterflies are tougher than you think and they can make it through, though sometimes I wonder how they do. What they seem to suffer badly from are successive bad years of weather, so if one summer is wet they'll be okay as long as the next summer is drier and sunnier, because they can catch up. Late springs can be a problem but what's worse is when you get a warm spell and then it goes cold again. If something is hibernating as a chrysalis and we get a warm spell, between the warm weather and the daylight hours it triggers it to start changing into the butterfly, if that butterfly then emerges and we get snow, which we've had, butterflies cannot survive. They need 21ºC or 22ºC sometimes just to get off the ground. Two or three springs like we're having at the moment will be devastating.
So is that why we only see butterflies up until the early autumn, because they just can't survive the weather conditions after that?
They would have already done what they naturally need to do, whether it's lay eggs which survive the winter or sometimes it's the caterpillar or chrysalis that survives the winter. You've got four species of butterfly in this country that actually stay as butterflies throughout winter, they find holes in trees or stay in garden sheds. Species like the peacock butterfly or tortoiseshell butterfly, they'll start hanging around people's sheds because they know that's where they are going to spend the winter.
Are butterflies still declining now?
Most species are and most species will continue to decline simply because the areas where they live are not being managed the way they need to be. Areas of wasteland as people might call it, might hold a rare species of butterfly or a rare species of spider or bee or something like that, but that land is built on and that species goes away. We're building on tiny fragments of land which may just hold a surviving population of butterfly or moth. Very rarely do you have one species that stands alone, there will normally be another species that relies on it - whether it's pollinating it or feeding it. We've got butterflies in this country that rely on ants to survive and if the conditions aren't right for the ants then the butterfly can't survive. It's called symbiosis.
How did you first get interested in butterflies?
My family were always into just enjoying wildlife. I guess when money was a bit tight we were just taken out to enjoy the countryside. I always seemed to want to know what things were, not necessarily why they were there or what purpose they had, I just liked to know what I was looking at. Seeing a butterfly in the wild I just wanted to know more about it, what it feeds on and what the caterpillars feed on and then I found myself looking for butterfly eggs and rearing those through. There's nothing more satisfying than finding one egg, rearing it right the way through and releasing a butterfly, and that's how I grew up. As soon as I had transport of my own I started getting involved in local conservation projects and groups which at the time was the London Wildlife Trust. Before I knew it I was on the management team as co-warden of a nature reserve down in Croydon specifically managing an area for rare butterflies - the small blue, brown argus, dingy and grizzled skippers, really quite rare butterflies. I loved to see them and rather than just enjoy seeing them I wanted to know more about them and study them.
Through the conservation group we were given a unique opportunity to rebuild an old Victorian greenhouse, so we had the land within the walled garden to create a wildflower meadow for the British species, and would have the tropical species in there as well. It's fantastic hearing and seeing tropical butterflies, but the British ones are every bit as beautiful. They might be smaller but we've got some stunning butterflies and being able to rear those and actually reintroduce them into the wild, as we're doing here, it's bringing them back from extinction basically. We wouldn't have had the opportunity to see arguably one of the most spectacular butterflies in this country, the purple emperor, now we've got people coming from all over Essex to that area of woodland and seeing a butterfly that they would not have seen without intervention - and anyone can get involved with that.
For more information on Tropical Wings Zoo visit www.tropicalwings.co.uk
Image courtesy of Graham Nicklas