Turning leaves are ordinarily the loveliest part of this lovely month, but this year the leaves are still green — drooping but green — and the few that have already fallen are dry and brown. The September rains they needed for October color never materialized. Here in Middle Tennessee, September 2019 was the driest on record: Somewhere in this region someone got .02 inches of rain last month, I hear, but at our house we got none.

And yet the light is nevertheless October light, and light is one of the seasonal triggers that tells migratory birds when it’s time to move on. According to the indispensable website of the Cornell Lab of Ornithology, more than 650 species of birds nest in North America, and more than half of those species migrate.

These days I stand at the window every chance I get to watch the last of the ruby-throated hummingbirds drinking from the feeders I’ve set out to compensate for the loss of wildflowers during a drought year. The ruby-throat migration is well underway now, never mind the persistent summer temperatures, and these are not the same birds that nested in my yard earlier in the summer. Those birds long ago abandoned their efforts to keep my feeders for themselves and departed for their wintering grounds in Central America. I hope some of them have made it safely across the Gulf of Mexico by now.

The birds I’m watching through my window are merely stopping by on their own journey from nesting grounds much further north. They too will be gone before long. It’s a predictable rite of autumn, more regular, now, than rain. In years past the last hummingbird arrived in my yard during the second week of October, and there is no reason to believe that this year will be any different. The weather is unpredictable and the climate is radically changing, but the light of October is still quiet and mild. And these iridescent avian jewels still take their cue from it, just as they always have.

In August the resident hummingbird wars are fierce, so violent that I’ve seen one bird knock another to the ground. The travelers are much less inclined to quarrel, too tired or too intent on conserving energy to engage in battle. They rest, one at a time, on the feeder’s perch and drink and drink and drink. Then they lift into the air, weightless, immune to the pull of gravity, and take cover again in the still-green leaves of a nearby tree. One day they will leave and be gone for good. But no matter how long I stand at the window and watch, I will never know which time will be the very last.

Margaret Renkl is a contributing opinion writer who covers flora, fauna, politics and culture in the American South. She is the author of the book “Late Migrations: A Natural History of Love and Loss.”

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