A few weeks ago I was bidding farewell to a pair of my favorite bog sparrows, the Eastern Towhees, when I realized they weren’t alone. There was another pair of favorites in that bush, the White-throated Sparrows. At that moment, bird migration struck me as even more fascinating than usual. Here were my towhees preparing to head south for winter after spending all summer at the bog. At the same time this pair of white-throats was arriving from clear across Canada to spend the winter here. These four birds travel thousands of miles migrating across North America to different parts of the continent, crossing paths maybe twice a year, and right now they are all right in front of me, in the same little bush.