Friday 7 June 2019

Fragile Beauty 6th June 2019

Wood Whites are, like many of our native butterflies a declining rarity, now only found  in the southern half of England and parts of Wales. Formerly they extended as far north as the Lake District. Their decline can be traced back to the early twentieth century when coppicing of woods was mostly abandoned, resulting in the loss of the butterfly's favoured habitat - areas of regrowth where coppicing had recently taken place.

Their fortunes were temporarily resurrected when the Forestry Commission commenced widespread planting of conifers in deciduous woodlands and the wide, grassed and shrubby margins of the newly created access roads provided exactly the kind of habitat the butterfly required. In the last thirty years of the twentieth century the habitat reached an optimum and the Wood White's fortunes looked good but eventually, as the trees aged, so the rides became too shaded for this sun loving butterfly's taste and they declined once more.

Today it is a rare butterfly but efforts have been made to preserve its habitat in both Forestry Commission woods and also certain suitable nature reserves by maintaining  rides that are wide and open to the sun and subject to regular cutting back of the vegetation on a three to six year cycle to keep the rides suitable.

There are currently slightly less than fifty colonies of Wood Whites existing in England and Wales with the main colonies being situated in Northamptonshire and Bedfordshire  and it was to a wood in Northamptonshire that I went today to seek an encounter with this fragile and delicate butterfly, the rarest of all our British White butterflies and one possessed of an understated great beauty

They are very distinctive and can easily be recognised, even from a distance, by their weak and uncertain, slow and fluttering flight, hardly ever flying more than a few inches from the ground. Get closer and you can see on a settled individual that the wings are distinctively oval and appear tissue thin whilst its body is markedly long, slender and tubular.

A Wood White perched on a Common Stork's-bill flower and showing to good
effect its long and slender body and grey shading on the wings
The weather today was again uncertain, with only periods of sunshine in between grey overcast conditions. Not so good for seeking out butterflies, especially one which so much likes sunshine and warmth. I arrived at the wood in cloudy conditions and was in no hurry to set off up the main ride through the wood, as I held little expectation of seeing a Wood White until the sun came out, if it ever did.

A typical ride through the wood with grassy scrubby verges
that are ideal for Wood Whites and maintained for them by
the Forestry Commission and volunteers
A Red Admiral settling on a wooden gatepost gave me some optimism and I had only walked a hundred or so metres before I found a Wood White, roosting on a pale purple Tufted Vetch flower. What a lovely  and exquisite combination of colour and fragility, the butterfly looking for all the world like a tiny white pennant as it clung to the flower head with its wings firmly closed and showing to good effect their oval profile. 

A Wood White perched on a Tufted Vetch flower
Wood Whites invariably perch with their wings closed but so thin are their wings that it is possible to see the black tips to the upper-side of the fore-wings through the closed wings. The undersides of the hind-wings have  a delicate subtle grey shading, looking like shadows cast across the wing's surface.

A Wood White roosting on a Greater Stitchwort flower head
Note the typically oval profile of the closed wings

This almost instantaneous success at finding a Wood White was completely unexpected and then to my great satisfaction the sun came out and, as if by a hidden command, I could see Wood Whites emerging from the grass and low undergrowth all the way up the sunny side of the ride. I carried on along the ride, rejoicing at this transformation and then the sun went behind a cloud and these delicate insects immediately sought a perch to settle on and await the return of the sun. They are not easy to find when perched and hidden in the grass  but I found a number of individuals perched low down on grass, leaf or flower just inches above the ground.

A Wood White perched on a Common Stork's-bill flower
The sun returned and so did the Wood Whites, emerging from concealment in the grass and undergrowth to flutter along in their slow and wavering quest for either females or a flower to nectar on. 

I found a perched Wood White which was being molested by two others. Presumably the perched individual was a female and the other two were males but the two suitors soon gave up and moved on but did afford me the opportunity, while they were fluttering around the probable female, to show their spread upper-wings and the black tips, something you do not see that often.

At other times a perched Wood White would be joined by another and the two would perch side by side on a flower head. This may have been a male unsuccessfully courting an already mated female as on the two or three occasions I witnessed this behaviour they parted after a minute or two and went their separate ways.

I walked the full length of the ride and then at a cross roads of rides turned right onto another more grassed ride but just as well populated by Wood Whites as the one I had just walked. 

By this time I had counted over sixty Wood Whites, more than I have ever seen before on one visit. These days Wood White colonies are said to contain only a few dozen individuals but here there seemed to be considerably more  and there can be a burgeoning in a colony's population if the previous year was warm and sunny, resulting in a large number of eggs being laid in that year.

 Wood White  roosting during a cloudy spell
After a couple of hours I stopped to return along the same rides just as large grey clouds moved over the sun. What a difference it made to my surroundings. From a delightful sylvan scene of dappled light and shade in a variety of greens, the wood became dark, dull and somnolent. The  fluttering white forms of Wood Whites disappeared and the bird song ceased. It was quiet and an expectancy of rain came with a rush of wind. I stood under a large Oak and waited for the downpour but it never quite materialised. Only a few rain drops, nothing more. Fifteen minutes later the sun moved up the ride toward me and the wood was transformed, illuminated once more into a place of joyous nature.

Wood White heaven
A Garden Warbler chortled his song loud and clear from a nearby Sallow and my return walk to the car park was one that was accompanied by any number of the delicate Wood Whites, each butterfly flying along the verge of the ride beside me as if in farewell.

What a pleasant morning to lift the spirits.

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