Monday 6th August 2018

Butterflies in Avatar My website has been very silent recently, mainly because much of my free time has been spent typing up the journal entries of J J Walker, my great grandfather’s brother-in-law, from his journey on board HMS Kingfisher through French Polynesia in 1883 (more about that in a forthcoming post). However, I cannot resist recounting the story of my encounter with one of my dream butterflies, which finally took place on 8th July this year, on the famous “Glass Bridge” at Zhangjiajie, in Hunan Province, China. The butterfly concerned is actually not rare, but I had missed seeing it when I lived in Japan, and I had dreamed of finally coming into contact with it ever since. It is the Giant Purple Emperor, Sasakia charonda, known in Japanese as Oo-murasaki, or “Big Purple”.

This summer, in early July, I joined a non-birdwatching and non-butterfly-watching tour group with a Shanghai-based company called M2 Adventure to hike through the spectacular limestone mountains at Zhangjiajie, familiar to anyone who has watched the film “Avatar” (which I have not!).

This area, in Hunan Province, in south-central China, is famed for the extraordinary limestone pinnacles that dominate the landscape, and we hiked up on the first day, stayed overnight in a local village inn, and then visited the extraordinary “glass bridge” on the Sunday afternoon before hiking back down again.

This bridge opened in 2016 and stretches 430 metres across a canyon 300 metres deep. There are all sorts of warnings saying that people with high blood pressure, heart conditions or other medical conditions should not cross, and no luggage may be taken, including any cameras other than mobile phones. In fact, although there are glass panels in the floor of the bridge, it is very far from being a glass bridge; in fact it is a metal suspension bridge, but with glass panels set into the floor. Tourists have to cover their shoes with cloth bags to protect the glass, but even so, it is already scratched, and of course it reflects the sky, so I at least did not find it frightening looking down through the panels, although there were some people who were clearly affected by the height. 

When I was about a quarter of the way across, suddenly I saw an enormous butterfly gliding past me at about waist-height; I immediately recognized as the prized Giant Purple Emperor, Sasakia charonda, which I had for so long waited to see. 

I thought I would only see it briefly, as it sailed over the parapet of the bridge, but then it came back, and to my utter delight, it settled on the protective fence, and I was able to admire it at leisure, and to take several photographs of this splendid creature, both with its wings open and with them closed. The only disappointment is that in none of the shots can one see the extraordinarily beautiful purple sheen, which only appears in certain lights. Finally, it sailed off, and then powered its way along the bridge towards the other side of the gorge.

A short distance further on, I spotted another interesting butterfly perched under the glass, and I managed to get a shot of this through the panel. I later identified this as another relative of the Purple Emperor, Chitoria pallas. Named after the Prussian naturalist Peter Simon Pallas (1741 – 1811), this species appears to be little known, and it does not feature in much literature or on many websites, so I felt privileged to see it, albeit through glass.

Full of excitement at these two great finds, as I approached the far side of the bridge, I noticed more and more butterflies under the glass, some beating their wings desperately against the panels, and others sitting exhausted on the metal surrounds. Yet more were already lying dead on the flat metal bars a little further below. It became clear to me that this wonderful bridge, beautiful as it is, was proving lethal to large numbers of butterflies, which fly in underneath, and then get trapped. It is not that they could not escape, because in fact they could, but they do not know to fly downwards, away from the light. Consequently they beat themselves to death under the bridge.

A sad unintended negative consequence of the construction of what is otherwise a beautiful and attractive structure. Luckily, this part of China is very well forested, so the number of butterflies affected in this way is probably insignificant in the grand scheme of things.