Birds in Fog: Circular Flying Keeps Flocks on Track

If good old Santa Claus relied on cranes instead of reindeer, Rudolph may have never had the chance to prove his worth. That's because sandhill cranes can apparently navigate even the thickest of fogs with a surprisingly clever strategy.

That's at least according to Eileen Kirsch of the US Geological Survey's Upper Midwest Environmental Sciences Center in La Crosse, Wisconsin.

Kirsch recently had the rare opportunity to watch sandhill cranes (Grus canadensis) in the Horicon wildlife refuge still set off from their roost in early morning hours, despite the fact that a heavy fog had descended. The results of her observation were published in the journal BioOne.

"In good visibility, cranes usually departed the night roost shortly after sunrise and flew in relatively straight paths toward foraging areas," the report reads. "In fog, cranes departed the roost later in the day, did not venture far from the roost."

Caution, Kirsch explained, was to be expected, but what occurred when the birds did finally venture out was a surprise. (Scroll to read on...)

"They were going every which direction, which we've never seen before," she recently told NewScientist. Kirsch went on to explain that the birds flew in expanding circles - a strategy that could help them keep their bearings.

The birds also called out to one another far more loudly and frequently than normal - behavior that very likely helps them keep track of one another and stay in formation.

"The only time in this 2-year study that observers heard young of the year calling was during the fog event," the researchers noted.

Still, this careful circling flight pattern and frequent calling isn't foolproof. The scientists also noted that lingering cranes were more likely to smack into "anthropogenic obstacles," such as buildings, cars, and telephone poles. It may pay then, for these cranes to get themselves a Rudolph after all. Seeing as it's August, they might even get a discount on a convincing lawn inflatable!

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