Fortunately, when we came across the butterflies we were not the only ones there. A group of dedicated butterfly photographers was already on the scene, among them Les Day, keeper of the beautiful and informative web site SamuiButterflies (who kindly provided me with some useful comments on this writeup).
Les provided Ian Redmond and me with an instructive introduction to the insects we were seeing and their behaviour, and if you click on the video link above you can enjoy it too. The video also includes a couple of butterflies you won't otherwise see in this post: the Five-bar Swordtail (Graphium antiphates), the Dark Blue Tiger (Tirumala septentrionis) and the Paris Peacock (Papilio paris paris).
The diversity of species in the carpet of butterflies before us was so enormous that I will need two posts to share it with you (Les notes in his own account that he had never seen so many puddling butterflies in his life). In this one, we'll take the broad view (plus adding in a few species that I came across on their own).
More of the same - but here, on the right in this photo, the gulls and swordtails are joined by another abundant pierid, the Striped Albatross (Appias olferna).
Pierids are not usually considered (especially by northerners) be the most startling of butterfly kind, though there is something ethereal about a delicately-fluttering cloud of ivory-coloured butterflies shifting and dancing at one's feet.
The sawtooth gets its name, or at least the first part of it, from the bright red blotch at the base of the hindwing. According to Les, this butterfly and its relatives are thought to be called "sawtooths" because the leading edge, or costal border, of the forewing is toothed like a (very small) saw. This combination of colour and pattern makes it quite like another colourful group of pierids, the jezebels (Delias spp.) - apparently both genera are distasteful to birds, and they may mimic each other to reinforce the warning to potential predators.
Another flash of pierid colour pops up here, as a Yellow Orange Tip (Ixias pyrene) takes flight from a cluster of albatrosses and Lemon Emigrants (Catopsila pomona).
Back on the ground, he displays the orange patches that give him his name.
Still more colourful pierids: this time, an Orange Gull (Cepora iudith), flanked by two Yellow Orange Tips (showing, this time, their yellow undersides).
Side by side: a Striped Albatross taking off, an Orange Albatross, another Striped Albatross and a Common Gull.
The shifting array of pierids was eye-catching, no matter which species we were watching.
As this kaleidoscopic burst of butterflies shows, the whites, yellows and oranges of the pierids can outshine the hues of even the swallowtails.
Indeed, next to them these Chain Swordtails can seem comparatively dull.
Among them there are other butterflies that look quite different - butterflies that resemble far more closely some of the danaiine crow butterflies. They, too, however, are swallowtails; indeed, they are members of the same genus, Graphium. They are, as far as I can tell, Spotted Zebras (G. megarus), and their resemblance to the apparently evil-tasting crows is a case of Batesian mimicry - imitation of a toxic or foul-tasting model species by a mimic that, were it not for its appearance, would make a quite satisfactory meal (for a passing bird, at least).
After all the excitement of the puddling swarm, it may be a bit anticlimactic to turn to individual butterflies like this one. Nonetheless they, too were part of our butterfly day, so here is (I think) a Burmese Sailor (Neptis leucoporos cresina). Mind, I say, I think that is what it is, but there is a seemingly vast horde of butterflies in Neptis and related nymphalid genera that look annoyingly alike. Also, are these butterflies properly called "sailers" (meaning things that sail) or "sailors" (e.g., jolly jack tars)? I have seen both, but I prefer the latter (though in Europe they are called "gliders" from their manner of flight, so "sailer" is not inappropriate) if only because it matches the name "lascar" used for the brown members of the group - another case, I suppose, of old butterfly names displaying the racial stereotyping of the time when they were coined.
Another representative of a confusing group - a Common Five-Ring (Ypthima cf baldus). Note the "cf", a scientifically acceptable way of saying "I'm not at all sure I have this right".
Hovering around the edges of the swarm were a few members of the family Lycaenidae, the blues and hairstreaks. I am putting this one down as a Common Lineblue (Prosotas nora).
The butterfly arousing the greatest excitement among Les Day's team of butterfly experts was this one: the Great Nawab (Charaxes (Polyura) eudamippus eudamippus), apparently a real prize for butterfly-watchers from southern Thailand as it reaches the southern end of its range here. The nymphalid genus Charaxes (if that is where this species really belongs) is primarily African, and contains many of that continent's most spectacular butterflies. The Greater Nawab is at the eastern end of its range here, as it's Urdu name - a title of rank in the Moghul Empire - implies.
For the rest of us, even the common species were entrancing enough - and Ian was more than willing to transform himself into a salt-feeding station for an Orange Albatross to celebrate the occasion.