A couple of times I have been a scientific adviser for the British Broadcasting Corporation, better known as “the BBC of London”. In 2004 I collaborated in the production of Life in the Undergrowth as an adviser on velvet worms (Onychophora: the “living fossils”), but many years ago I had also been an adviser for Trials of Life, hosted by David Attemborough. The subject, an extraordinary genus of butterflies that fills the air with sounds that have two functions: defending a territory and attracting the female. Filming these musicians was almost would prove difficult as deciphering the secret of their sound mechanism.
When young Charles Darwin first met the noisy Hamadryas butterflies in Brazil, he wondered how they produce their sounds, but left the problem to the wisdom of other British naturalists. However, the answer came a century and a half later from a team of Costa Rican scientists who used high speed photography, computer analyses of the sounds, electron microscopes and much patience. Sound is produced by the mechanical action of a highly modified and complex vein system. Exactly how the mechanism is triggered, however, is still unresolved.
Here is the story of a BBC effort to document the butterfly's behavior...
When I arrived to the Punta Morales Marine Laboratory, in the Pacific province of Puntarenas, the BBC crew was there already. Our goal: filming how male Hamadryas butterflies attack intruders that fly inside their mating territories. During my study of these odd insects that produce loud sounds during aerial encounters with potential enemies, I had used a technique invented many years before by the Dutch ethologist Niko Tinbergen. A dummy made of a properly shaped piece of cardboard (or a dead Hamadryas male in may case) is hanged with thread from a stick like bait from a fishing cane. The reaction of the males was immediate and very aggressive: they flew towards the intruder and attacked it, even clashing against the dummy. This happened during my experiments, designed to learn where the territory of each male ended, as well as during a demonstration to a BBC producer months before.
We prepared everything, the director said "quiet everyone... action!", the narrator said his carefully memorized part with the excellence that has made him famous, moved the dummy in front of the territorial male... and nothing happened. The butterfly just stayed there looking at these ridiculous humans with total disdain. It was not the butterfly's look that worried me, but the look in everyone’s faces when they turned to me. I was the expert and of course they expected not only an explanation but a solution. Despite the heat, there was cold sweat in my brow.
"Perhaps it is the way you move the dummy, or the day is not hot enough", I tried saying. But after several other attempts, this particular Hamadryas continued ignoring us like a British prince would ignore misbehaving children in a crowd during a parade.
Maybe if we waited a real male would come and our butterfly would attack it and click, I suggested. And wait we did, besides looking for other males in the area, of course with no results. People began to look at me with expressions that made me imagine their thoughts (Who said these butterflies click? I haven't heard them... And that story that they fight seems so weird...). So we concentrated in several takes of the narrator's presentation, to use the best one. Once I noticed something that seemed to be incorrect grammar and commented it aloud. I was sorry before I ended speaking: who was I, nurtured in the milk of Costa Rican Spanish, to correct a BBC expert's use of Shakespeare's language? But the narrator kindly said I was right and explained that foreigners often learn better grammar from their teachers than the native speakers from the people who surround them!
Despite this diversion, our butterfly continued as motionless as a dummy and the high cost of having the whole team (director, narrator, cameraman, sound engineer and assistants) in Costa Rica accumulated every minute. The title of an Australian television program about zoological films came to my mind: Never work with animals . While thinking of it, I unconsciously stepped back and crushed a dry stick on the ground. This happened just after the "quiet... action" instruction: the killing look of the director needed no comment!
Julian Monge - Nájera / State Distance Education University (UNED), Costa Rica /
