Saturday, October 07, 2017

Painted lady butterflies out-monarch the monarch

Probably every Canadian schoolchild knows the story of the monarch butterfly and its dramatic migration each fall from Canada down to the cloud forests of Mexico, and then the migration back again in the spring of the descendants of those southern migrants. But few, if any, European schoolkids are aware of the even more impressive exploits of the painted lady butterfly.
In fact, up until recently, few scientists knew the full story. But a detailed radar study, published recently in the journal Ecography, shows that the annual disappearance of millions of painted ladies from Britain is not just a mass die off, as has been generally assumed heretofore. The butterflies are known to arrive in the UK and other northern climes to breed each summer, but it has never been clear until now where they go to when the cold weather begins to arrive. They are not seen migrating south again in the fall or early winter, as the closely-related red admirals do, and it has widely been assumed that they just die, unfulfilled (the so-called "Pied Piper Hypothesis").
What the new data shows is that they do in fact migrate south, but at altitudes of between 500 and 1,000 metres, invisible to the naked eye, taking advantage of favourable winds to travel at speeds of up to 50 km/h. And, like the monarch, the painted lady's journey is also a multi-generational one, taking six generations to complete a mind-boggling 14,400 km round trip between tropical Africa and the fringes of the Arctic Circle.
The monarch's journey is certainly an impressive one, and worthy of the note of millions of schoolkids. We now know, though, that the painted lady out-monarchs even the monarch.

No comments: