Sunday 14 August 2011

A Swift Recalculation, and Some Blues

Last evening, sitting in my son's garden, I looked up and saw... a solitary swift, flying purposefully overhead - this a full eight days after what I had taken to be the end of my swift summer. What was even more remarkable was that my cousin in Derbyshire also saw a swift last evening, followed by another lone straggler today. So there may yet be more. The end of the swift summer seems to be less abrupt and total this year than it usually is.
The swallows, of course, are still with us in numbers. I was watching them skimming a field earlier today as I took a much-needed walk in the Surrey Hills. It was a day of warm sun and dark cloud, and when the former predominated the butterflies were merrily flying in good numbers. Mostly they were the familiar Meadow Browns, dark Ringlets and jolly Gatekeepers, those butterflies that best seem to catch and embody the relaxed, easy-going mood of high summer. A little busier and harder to follow in flight were the Small Heaths, pale little beauties with bright eyespots on the underside of their forewings. And then, much livelier and easier to lose sight of, there were tiny Brown Arguses (also having a good year), which fly fast and erratically, then land very suddenly to bask. The mystifying thing about them is that they appear pale and silvery in flight, suggesting a very small Blue - yet when they land and open their wings, they turn out to be a rich dark brown, studded all round the margins with dots of bright orange. Why is it that they look so completely different in flight?
The great joy of my walk, though, was to find myself among Chalkhill Blues, my first this year, and they were flying in their dozens - more than I've seen in ages. These too are pale and silvery in flight, but that's because they are pale and silvery, for Blues - and also large, for Blues, so mercifully easy to identify. As a boy, when I first learnt to identify them, I used to think the name was descriptive of the colour, a chalky blue, rather than the habitat...
And just now I looked up (I'm in the garden) and saw - another swift! It's still summer.


  1. My understanding is that in some butterflies the colours of their wings come not from pigments but from the sophisticated structure of the scales which make up their wings. These scales reflect light of certain wavelengths, which we see as colour, while the other wavelengths pass straight through. As with reflections on glass, a butterfly's wings, which we see as extraordinarily colourful, may have no intrinsic colour at all. They act as reflectors, and ones so refined that we've only recently understood how they work. Is this correct? If so, it's amazing and another good reason to enjoy every encounter with these creatures.

  2. I think that's right Mark - and, as you say, it makes it all the more amazing. I believe it's also true that polar bears have transparent fur and black skin, which together create an appearance of snow white. Not that I much fancy polar bear spotting...

  3. glad that summer's still here Nige - I was fair depressed after last week's swift missive, without your post I probably would never have noticed that they'd all disappeared.
    In fact, I suppose that thanks to you I shall now spend the first week of august for the rest of my years scanning the skies ready to be the harbinger of doom that tells everyone that summer's over...

  4. Great stuff Worm - but the beacon of hope still burns, so long as there's a lone swift up there somewhere. Keep looking...