One of those persistently frigid mornings earlier this month, I heard outside the bedroom window two notes that have been absent for, well, a long time. Not quite believing my ears, I looked out and saw, sure enough, the phoebe was back, bouncing from the bare Bebb’s willow to the gray-birch branches and inspecting the nest up under the eaves to see what damage the winter chaos did.

Around the same time, Bonnie and I were startled one evening by the clacking and clattering of Canada geese flying low over the woods. Spring springs eternal. Purple martin scouts last week were checking to see if the bird condo at the Unity park is still in orderly condition. Ducks are bringing symmetries to the air again as they bustle back and forth in twos and threes over rivers and half-frozen swamps.

But to me the kinetic sign of the time is the juncos.

They arrive in huge crowds around this time every year and take over the yard for a day or two or sometimes a week. Some birding summaries say their flocks are as large as 25, but I have to tell you, at our house they usually come in bop-hopping droves. Juncos rooting around in leaves under the feeder. Juncos bouncing from spruce to ground and back to spruce. Juncos exploring in the driveway and around snowbanks like fifth-graders at recess. One birdwatcher on the Maine Birds mailing list reported “bushels of juncos” at his house. The flock is a little moveable cosmos of its own.

Our dark-eyed juncos are of the slate-colored race. Junco hyemalis, they’re called by the scientists, among whom there has been discussion in recent decades about what strictly constitutes a junco species, as the different slate-colored, white-winged, Oregon and gray-headed races interbreed. Anyway, they are a kind of sparrow, living in fir woods and feeding largely on seeds and, during breeding time, bugs such as wasps, moths, butterflies and even ants. They nest mainly on the ground or in the root tangles of fallen trees. I haven’t actually seen a junco nest, since in our yard they’re transients of April and October on their way to and from winter digs as far south as Mexico and Florida and breeding grounds as far north as Labrador. In fact they are apparently the original “snowbirds.”

A widely reported study of junco mating behavior discovered that male juncos with high levels of testosterone found their way with heightened success among many different females, so each high-T male was responsible for a lot of eggs. At the same time, the junco studs were far less attentive to the nests and chicks than the males that were less disposed to philandering, and so fewer of their offspring survived. Some of the scientists seemed eager to interpret this as a moral lesson for humans.

Thoreau, who taught us to see the larger moral spheres of the universe in the natural world, mentions the juncos here and there in his journals. In “Walden” his principal avian spring-sign seems to be the geese: “As it grew darker,” he says of one evening during the transition out of winter, “I was startled by the honking of geese flying low over the woods.”

They’re one of spring’s revelations, signifying “the coming in of spring is like the creation of Cosmos out of Chaos.” That is exactly how, every year, the juncos come to the back Troy woods.

Dana Wilde lives in Troy. His writings on the Maine woods are collected in “The Other End of the Driveway,” which is available online or by writing to him at naturalist@dwildepress.net. Backyard Naturalist appears the second and fourth Thursdays each month.