Magnetic Instructions

There is a bird in Sweden called the thrush nightingale. This bird migrates from Sweden to southern Africa every Fall and back every Spring. There is a major obstacle in the way of this journey--the Sahara Desert. It takes five days for the thrush nightingale to cross the Sahara, and there is no food available to it in the desert. The birds fly at night and rest during the day, but before crossing the Sahara, the birds stop and fatten up, gaining up to twice their body weight before doing the Sahara flight. Young birds separated from others of their species still do this, so it is clearly not a learned behavior.

Horseshoe magnet Recent studies by Thord Fransson of the Swedish Museum of Natural History and his colleagues have shown that the birds read magnetic variations surrounding the Sahara. When these signals are duplicated in laboratories, captive birds stop their normal activity and gorge themselves radically increasing their weight.

It appears that in the thrush nightingale's brain there is a programmed section that tells the bird to gorge itself so it can make the crossing of the Sahara. How such a genetic signal could be programmed by trial and error is almost impossible to imagine. This is another example of instinctive behavior designed to overcome a major obstacle to being able to make a seemingly impossible journey. Anything designed has to have a designer.

--Reference: "Magnetic Field Tells Nightingale to Binge," by S. Milius, Science News, November 3, 2001, page 278

--John N. Clayton


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