Zugunruhe!

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Zugunruhe!

It's German: Zug (move) and Unruhe (anxiety).

Ornithologists know its meaning. Roughly translated: migratory restlessness.

Throughout the tropics, millions of birds are starting to feel the need to move on. Fly north. Claim territory and raise a family.

The desire is strong, genetically encoded. Capture a wintering redstart in Venezuela and put it in a cage. It will in time begin to hammer itself into the north side of the bars. Crash. Flutter. Crassssh. Set it free and it'll fly across the Gulf of Mexico towards North America. It knows the way home.

Day length, photoperiod, is the key, the trigger. The crack of the starter's pistol. Bam. And the days are most assuredly getting longer.

In North America, over 500 species migrate, go somewhere. West to east, north to south, high elevation to low. Or simply moving around within their range.

To date, swallows, martins and osprey are all reported to be back home in Tennessee. The rest of the migrants will soon follow.

That's zugunruhe!

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