Because today, here in this low green valley where it never freezes, it’s freezing, icy rain slanting down and down, I change out the hummingbird feeders every hour on the hour. This morning the male Anna’s hummingbird was waiting for me across the fence, resting on a thin branch in the bare rose of Sharon. Midday, as I switch empty feeder for full, he buzzes over immediately—fifty wingbeats per second, furious thrum and dazzling rump shake—and jabs his beak into a plastic flower.

My twelve-year-old son’s one good friend is half his size and has a sweet, lopsided smile. The boys were on the same basketball team this year, my son standing beneath the basket gathering rebounds, my son’s friend bouncing around the three-point line. When my son’s friend runs, he leans the top half of his body forward, as if against a wind, and pumps his thin arms high, nearly above his head, his small hands tightened into fists.

I retreat into the house but can’t stop watching the Anna’s. I mean, look at him! Little knuckle of feather and muscle, he weighs at most two-tenths of an ounce. He hawks insects, eats tree sap, dives at a speed of 385 body lengths per second—almost ten times the rate of a fighter jet—tail feathers cutting against the wind so hard they emit what scientists have termed an “explosive squeak.” As he perches on the feeder, long tongue licking at the nectar, his crown and gorget iridesce an impossible red.

Since he’s switched foster homes—it wasn’t up to him; it just happens—my son’s friend has been able to spend more time at our house, which is good. Because we live in a relatively small town, the social worker had to tell my wife and me who the boy’s biological father is. That way, if we see him—tromping along the river trail or casing the public library, high and wrathful, shirtless, swearing at the sky—we can respond appropriately if our son’s friend sees him as well and goes silent or tries to hurt himself.

Now the Anna’s shivers the wet from his wings and zips into the air—up then down—and arrows right at me, landing mere inches away, on the sill, in the rain shadow of the eave.

We don’t have all the facts—the social worker closed her eyes, her head dipping almost imperceptibly—but she did tell us that before he was moved into the foster system, at night, after his biological mother had passed out, this one impossibly small boy would tuck his younger siblings into bed and, in case his father somehow found his way home, sit in a kitchen chair across from the front door, an old air rifle pumped and butted up against the slender wing of his shoulder.

I call to the boys, and, like boys, they charge into the kitchen, loud and loose-limbed. At the window, though, they go still, lean toward one another, whisper and point. The world beyond is shrouded in gray rain and thin, dirty skeins of ice, but here, right here, the Anna’s swivels his bright, tiny head—Isn’t this, too, impossible? Isn’t all of it?—and fixes us in the dark shimmer of his eye.