Wednesday, January 20, 2010

Discovering the trade winds

When were the trade winds discovered?

I always had this hope that it was my alleged relation, William Dampier, who documented his experiences in his book with the snappy title of "A discourse of trade winds, breezes, storms, seasons of the year and currents of the torrid zone throughout the world".

But it seems he was pipped by the much earlier and humbler Arctic Tern whose annual migration is shown in the figure above. What struck me straight away is how they follow the route of the round the world yacht races, but then of course the trade winds help both sailors and birds.

Setting aside the long distance and resilience required for an animal weighing around 100g to travel a round trip of 70,000km from pole to pole and back, there is a question of how does it navigate its route?

I can see how such a behaviour can come about: if in the depths of time the birds flew at random the ones that picked up the trade winds would get there quicker using less energy and hence be more effective in evolutionary sense. And once learnt the following generations could follow the lead of its parents.

But maybe we underestimate them as we do so often, overconfident in our superiority over mere birds. Rooks in particular have been shown to be tool using animals.

Anyhow more on this story here.

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