The first faint hint of fall has blown in overnight, finally breaking the heat and humidity of the Mississippi summer. Hundreds of ruby-throated hummingbirds have also flown into town, tiny neotropical migrants from points as far north as Canada, heading south to Mexico, Guatemala, even Panama. Near where I’m standing, some of these hummers begin jockeying for space at a bank of feeders, becoming a blur of green, ivory, and crimson as they chase one another through the morning sunshine and dogfight high into the September sky.As I watch, one of the combatants peels off from the skirmish and dives down to a feeder hung inside a green wire cage. A trapdoor drops behind it, and soon the bird is being measured and weighed by Fred Bassett, a retired Air Force lieutenant colonel and former fighter pilot who, no stranger to dogfights, has now turned his full-time attention to these miniature flying machines.Bassett, one of only 100 licensed hummingbird banders in the United States and...