Wow, fun with words!

German.  Zug is the noun; the verb is ziehen, to pull.  A Zug is a 
train, or a pull on a cigarette, or a gulp of beer.

Ruhe is rest, Unruhe is unrest.

Zugvogel is a migratory bird.  Vogelzug is bird migration.

Here's the German Wikipedia entry:

/Alex DePillis
On 11/1/2014 10:03 PM, [log in to unmask] wrote:
> Zugunruhe is a term that describes the pre-migratory excitement and agitated behavior that birds sometime display just prior to starting out on a flight. Presumably, it's function is to communicate the birds' intentions to get moving and coordinate the departure? It's seen quite a lot in shorebirds, for example, when they make short flights often returning to land from where they took off, before launching out on the "big one".
> Sent from my iPad