Of all the summer visitors to the front garden, my favorites are the ruby-throated hummingbirds (Archilochus colubris) that flit from tree to feeder, performing breathtaking aerobatics with perfect precision like miniature barnstormers. Hummingbirds are aggressive for their tiny size; “Peterson Field Guides Eastern Birds” refers to them as “pugnacious.” They jockey for the prime position at the feeder, swooping and diving at their competitors to drive them away from the nectar source. Jim and I anticipate their return every spring from winter homes in Mexico and Panama and feel forlorn in September when they fly away again. In recent decades, the migratory range of the ruby-throated hummingbird has pushed as far north as South Carolina from the southern provinces of Canada. Of the 320 species of hummingbirds, the ruby-throated is the only species that breeds east of the Mississippi River, ranging from Canada to the Gulf Coast. The occasional rufous hummingbird, indigenous to the northw...