White-letter hairstreaks: back in Cornwall

I have a lovely butterfly book, inherited from my parents, dating back to 1968. The colour illustrations are detailed and painstakingly drawn; the text simple and hopeful. Why hopeful? I think because the words the author uses pre-date some of the more recent significant changes we have seen in our landscape, particularly those affecting wildlife, and there is very little about habitat deterioration or reducing species numbers. The book makes you feel that, at the right time of year and in the right place, you could walk out the door on a sunny day and see every single butterfly species you might expect to see.

Turn instead to Butterfly Conservation’s most recent report on The State of the UK’s Butterflies (2011), and the picture is of course very different.  Numbers of butterflies are reducing, with 75% of species showing a trend of a ten-year decrease, either in population numbers or distribution, with declining habitats suggested as a main cause. It’s a depressing picture, especially if butterflies have always been for you, like me, a joyful sight from spring through to autumn. Being very sensitive to environmental change, the problems we see in butterfly numbers are an indicator of all the wider issues adversely impacting our wildlife.

So, in the face of this, it is heartwarming and encouraging, and hopeful, when a species starts to make a comeback. And this time, it’s a Cornwall success story. The White-letter Hairstreak (Satyrium w-album) has not been seen this side of the Tamar for over 20 years, but it’s back! It even made the local news.

White-letter Hairstreak (800px-Ulmen-Zipfelfalter_(Satyrium_w-album)_2011-05-08)
White-letter Hairstreak (License Creative Commons Attribution-ShareAlike 3.0 Unported)

The great news was announced at the Annual General Meeting of the Cornwall Branch of Butterfly Conservation (BC) last weekend (16th March). Cornwall BC had been looking into a re-introduction of the species, working together with national BC and two White-letter Hairstreak experts, Liz Goodyear and Andrew Middleton, who came down to Cornwall in February to do a survey for the butterfly (or rather, for its eggs) – a pre-requisite for a re-introduction scheme. And, hey presto, they found eggs! Just three, at two different sites in south-east Cornwall, but firm evidence the butterfly is here, and breeding.

How did it get here? There are some colonies across the Tamar in Devon, so they may possibly have arrived from there. Or it is not impossible that they have been clinging on in Cornwall, in very small numbers, but unfound, even though experts have been looking over the years – this is a fairly cryptic species.

English: Photo of David Elm afflicted by Dutch...
English: Photo of David Elm afflicted by Dutch Elm disease taken at Great Fontley, UK. (Photo credit: Wikipedia)

As well as suffering from some of the same issues as other butterfly species, the White-letter Hairstreak has had one specific, but very major, problem. The one and only food plant of its caterpillars is elm trees and, of course, elm trees in the UK suffered devastation in the 1960s and 1970s from the beetle-carried Dutch Elm disease. And that meant all the species associated with elms, like the White-letters, also suffered badly.

Not only did they reduce in numbers along with the elms, but White-letter Hairstreaks are a small butterfly, with a wingspan of about 3.5 cm, they are mainly brown (although their underwing patterning is lovely up close, with orange edges and the white banding that gives them their name), and they live mainly, and often in small colonies, in the tops of their host trees. This is why they are spectacular not so much for their looks as for being difficult to find.

The adults are flying from the end of June through to August, feeding on honeydew in the tops of the elms. The best chance (still not good) of seeing their pretty pirouetting flight from the ground is early in the day or in late afternoon when they sometimes come down to nectar on flowers, in particular their favourite privet and bramble. My 1968 book suggests standing under a host elm and looking up, to catch sight of the fully-grown caterpillars silhouetted against the leaves – definitely written when they were more numerous!

Egg (after hatching) of the butterfly Satyrium...
Egg (after hatching) of the butterfly Satyrium w-album on an elm (Ulmus sp.) twig Scale : egg width = 1mm (Photo credit: Wikipedia)

The eggs are laid singly, usually at the scar marking the join between old and new growth of the twig. They look a bit like flying saucers, and you’d have to be an expert to spot them with the naked eye. The caterpillars emerge between late-March and June, a timing that coincides with the emergence of the elm flowerbuds on which they feed before moving to the leaves. They pupate, attached by a single silk girdle, between May and July, and adults can be seen from June.

Nationally, there is some evidence that White-letter Hairstreaks have been increasing, though it is difficult to separate actual increase from increased recording effort [UPDATE 26/3/2013 – see note at end of this post]. They remain nonetheless a priority species under the UK’s Biodiversity Action Plan, and this is why it is so special to find them back here in Cornwall. Here’s hoping they go on to make a good recovery.

Cornwall Butterfly Conservation members will be surveying elms for White-letters later in the summer. If you’d like to help with the search, contact them via their website here – they’d love to have as many people involved in this exciting project as possible.

UPDATE: The day after I published this post, Butterfly Conservation released (on 26/3/2013) the 2012 figures – see this link to the report in the Guardian. After the terrible summer we had last year, butterflies have fared extremely badly, including White-letter Hairstreaks which are now down by some 70%. This is a sobering thought after its rediscovery in Cornwall, and bad news for all our butterflies. Let’s hope for a better summer this year. And see the Cornwall Butterfly Conservation page (link below) for advice on how you can help butterflies.  

References

Butterfly Conservation 2011. The State of the UK’s Butterflies, 2011. Butterfly Conservation, Lulworth, Dorset.

Mansell E, Newman LH 1968. The Complete British Butterflies in Colour. Ebury Press, London.

Links

White-letter Hairstreak: priority species factsheet

Cornwall Butterfly Conservation website

UK Butterflies

Kynance Cove on a Spring morning

Shell on Serpentine, Kynance Cove

I went to Kynance Cove on The Lizard this Saturday morning, complete with my lovely sister and a small dog called Podge. As far as we know it was Podge’s first trip to the sea (she is a rescue dog), and she had a whale of a time, once she realised how water behaves on a beach!

With Podge, discovering the sea
With Podge, discovering the sea

It was a lovely day, sun shining, a crisp but not-too-cold breeze, salt on the air, and a very quiet beach, with only a few other friendly people sharing the beauty of the sea and sand. Dogs are allowed from 1 October until Easter, and Podge, after scrambling nervously down onto the beach from the rocks (she only has little legs), enjoyed the experience as much as we did.

Kynance Cove is lovely to visit in summer – it’s warm and you can paddle and enjoy an ice cream at the cafe – but it’s also very crowded. At this earlier time of the year, when the cold edge is leaving the air but the visitors haven’t yet arrived, it’s a different place – more peaceful, relatively secluded. You have longer to contemplate the view and investigate the swirling patterns of the serpentine in the rocks.

Kynance Cove
Kynance Cove
Sea campion at Kynance Cove
Sea campion at Kynance Cove

On our way across the beach towards the cafe we enjoyed some of the early signs of spring, including lesser celandine and sea campion. The mass of flowers that will soon adorn the cliffs are not yet there, but this made the sight of these few early flowers bravely blooming all the more lovely, with no competition to detract from their prettiness. Seeing them, these short-lived plants of delicate beauty, set against the aeons-old famous exposures of serpentine, the swirling waves of the sea and the warm-coloured sand, is a reminder of the amazing contrasts of time and form we find in nature.

Kynance sky
Kynance sky

Also amazing was the delicious apple cake we enjoyed at the cafe, which we were delighted to find open!

If you want to take a spring trip to Kynance Cove, you can park in the National Trust car park signposted from the A3083 just before you get to Lizard Village. Parking there is free to National Trust members, but otherwise there’s a charge (less this time of the year than in the summer). It’s worth checking the tide times, as the beach is much more restricted at high tide.  But then, you can always take the path that avoids the high tide and enjoy a delicious cake in the cafe while you’re waiting for the beach to reappear…

Serpentine, Kynance Cove

Goss Moor and the source of the Fal

Living near to Falmouth, I am used to thinking of the River Fal in terms of its end as it joins the sea amid the activity and hustle of the world’s third largest natural harbour. Large ships anchored out in the bay, people teeming round the docks, either hard at work or visiting to enjoy the spectacle, pleasure boats, industry, and so on, are what come to mind.

River Fal Panoramic
River Fal Panoramic (Photo credit: Ross Tucknott)

But that’s not where I am now. I’m up on Goss Moor, several miles to the north-east, standing by the side of one of the many springs that make up the headwaters of the Fal. From half way across the Moor, the Fal is already a recognisable busy stream, both on the ground and from a map, but here, further to the east, the river has not yet formed, and the many small springs and trickles are making their way westward before joining together to wend their way south to Falmouth Harbour.

Goss Moor circular 'multi-use' trail
Goss Moor circular ‘multi-use’ trail. The archway allowed local people access to the Moor for grazing beneath a now disused railway line.

My day at Goss didn’t begin with the Fal. I parked in the car park at the southwest corner, close to St Dennis, and set off on the Goss Moor Multi-Use Trail eastward. Goss Moor, Cornwall’s largest lowland wetland, is one of three National Nature Reserves in Cornwall – the others are Golitha Falls and The Lizard – and Goss and Golitha tend to suffer by comparison with the more renowned Lizard reserve. I haven’t yet been to Golitha, but I can vouch for Goss Moor definitely being worth a visit. The multi-use trail is a good seven miles long, a full route round the moor, mainly off-road, partly on-road, making easy access for walking, cycling and horse riding, and a good running circuit as well, given the number of runners I passed (or who passed me!). It’s also relatively easy to leave the trail and make your way across the moor to investigate further off the beaten track.

Pylons across the Moor
Pylons across the Moor

As I set off on my walk, I was aware of many sounds – birdsong, the distant hum of traffic, cows mooing and sheep bleating, the St Dennis church bells (this was a Sunday morning), water somewhere trickling. But beneath it all, the continuous motif linking all these other notes, was the crackling hum of the pylons that are strung out across the moor, originating from the Indian Queens Power Plant to the west. Unexpectedly, this didn’t distract me from appreciating my walk, instead adding an edge to the bleak beauty of the place. People sometimes talk of pylons as ‘marching’ across the landscape, but these seemed rather to be rooted firmly in the heathlands at their feet, part of and not an intrusion on the scene. And why shouldn’t they be? – these particular ones have been here since the 1960s, and pylons have been a feature of the Moor since the early twentieth century. It is indeed amazing that a landscape that has been so heavily influenced by humans through the centuries – tin and clay mining, gravel extraction in the 1970s, the building of the modern A30, the railway and the power plant – should feel at the same time so peaceful and isolated.

Metal feet growing in the landscape on Goss Moor

I left the pylons behind, anyway, as I detoured from the main trail to take a path bending to the north, to find the Fal. This is perhaps not the most productive time to visit Goss Moor: it is known, amongst other things, for its Marsh Fritillary butterflies, the delicate flowers of Yellow Centaury, Lesser Butterfly and Heath Spotted orchids, all of which won’t appear until later in the year. I might have been able to spot the lovely little fern, Pillwort, or the rare Marsh Clubmoss, but I didn’t.

The River Fal as it begins its journey south from Goss Moor.
The River Fal as it begins its journey south from Goss Moor.

I did however find the Fal. Walking eastward, in the opposite direction to its flow, one of the most striking features is the reddish colour of the sediments in parts of the stream bed. As far as I can work out this is due to iron-rich minerals resulting from the geological and industrial processes in the area (any readers who have better information – please leave a comment as I would love to know more!). Goss Moor is a Site of Special Scientific Interest (SSSI), and the site description tells us that its soils have been heavily disturbed and influenced by mining, with these and the more recent gravel extraction creating open water pools.

Trees reflected in the red waters on Goss Moor
Trees reflected in the red waters on Goss Moor

I also noticed something I’ve seen before, but never in such abundance. The oily-looking film on the surface of still water pools isn’t in fact a small-scale oil slick, but a film created by Leptothrix discophora, a bacterium that uses iron for maintaining its life functions, much as we use oxygen, so it obviously thrives in the iron-rich environments here. You can tell it is not oil by poking it with a stick: oil will swirl around and not break up, whereas the Leptothrix discophora film breaks up into little platelets, a bit like cracking a thin film of ice. You can see this in the photograph below.

Leptothrix discophora on the water surface at Goss Moor
Leptothrix discophora film on the water surface at Goss Moor

After finding the Fal and pottering along the boardwalk on the ‘Marsh Fritillary Trail’, I rejoined the main track and did the full circuit of the Moor. I wasn’t quite so enamoured with the northern section for a ‘nature’ walk: I suspect that’s more because I love investigating the heathlands and smaller tracks, and because the  proximity to the main A30 trunk road in the northwestern parts of the trail was a little off-putting – there is a great view from the bridge over the A30, though.

Bench on the Goss Moor Trail - an interesting and sustainable use of a felled tree
Bench on the Goss Moor Trail – an interesting and sustainable use of a felled tree

There was plenty of interest, however. The leg running along the northern edge uses the old A30 – famous for its traffic jams in the past, but now a peaceful track with an interesting bench or two! Watch out as well for the milestone, dating from 1769 and resited to south of the bridge over the  new A30. In its original location it told you that you had 10 miles further to go before Bodmin – it would have seemed much further then than in these fast-speed days.

Catkins all in a row at Goss Moor
Catkins all in a row at Goss Moor

As I came closer to my starting point, through a more wooded area, there were many signs of Spring to cheer the scene on a cold and grey day – snowdrops, primroses, catkins hanging over the path, the fresh green leaves of soon-to-be foxgloves – all promises of a richer and more colourful sight to come.

I think, though, my favourite part of the walk was in the eastern section, alongside small pools and springs that are destined to become part of the River Fal but which, for now, have no names or separate identity. I wondered what vagaries of geology and time determined that these would become the Fal, flowing to the south coast and the busy shipping lanes of the open sea.

It’s good sometimes to remember that things have a beginning, and that while returning there cannot turn back time or alter a previous course, it can nonetheless refresh the mind with future possibilities, future directions.

I didn't follow this path over the red water when I was on Goss Moor - I wonder where it might have taken me...
I didn’t follow this path over the red water when I was on Goss Moor – I wonder where it might have taken me…