I was looking at the hawk mountain website and learned an amazing new word: zugunruhe
Its a compound german word, they always seem to describe ideas better than english words, that means move-anxiety.
In the northeastern United States, birds of prey migrate south from July through January. Decreasing day length in late summer induces zugunruhe, or migratory restlessness in raptors.
According to the wikipediea, scientists seem to think its an endocrine-induced instinct. And caged migrants exhibit zugunruhe behavior for the number of days that correspond with the length of their normal migration. I wonder if we are still feeling its impact as individuals descended from migratory ancestors. Maybe that's why people tend to feel like some vacations can be "too short" or "too long".
