Winter Birds Begin Singing Their Rites of Spring 

John Roach
National Geographic News

For some, the magic moment happened a week ago. For others, it happened just the other day. Many are still waiting, but some morning soon they too will wake to the lilt of a backyard bird pleading for a mate.

Chickadees will whistle "Phoebe," nuthatches will honk like a tinny horn, titmice will screech "Peter, Peter, Peter," and woodpeckers will hammer out their heart's desire with their beaks against hollow branches.

"These are all winter birds. It's still winter, but the light, the changing light, has a hormonal trigger, and that starts the birdsong," said John Hanson Mitchell, an editor with the Massachusetts Audubon Society in Lincoln and author of A Field Guide to Your Own Back Yard.

Mitchell said the singing of the winter-resident birds is among the first signs that spring is around the corner. Birders begin to report the sounds in the middle weeks of February.

John Dunning, an ecologist at Purdue University in West Lafayette, Indiana, said birds have photoreceptors in the bases of their brains that record the length of the dark period each day. As the darkness shortens, and as days lengthen, birds get spring fever.

"The photoperiod is very standard from year to year," he said.

"Days lengthen at a regular pace." Therefore, using the photoperiod to gauge the season is more reliable than, say, following cues such as an emergence of insects or a freshly sprouting plant, which could easily be fooled by a midwinter warm spell, Dunning added.

Winter Residents

The first birds to sing of the pending arrival of spring are the same birds that never left for the winter, Mitchell said. In Massachusetts winter residents include chickadees, nuthatches, woodpeckers, titmice, cardinals, and mockingbirds.

"They have millions of years of evolution learning to survive the winter," Mitchell said. "They're here because they know how to do it. Other species don't know how to do it, so they go south."

The winter residents survive by adapting to the available food. Nuthatches will scour the crevices of tree bark in search of insect eggs and grubs, for example. Chickadees and titmice feast on seeds. Woodpeckers hammer away at trees to fish out insects sleeping away the winter.

"[Woodpeckers] are well adapted to drill and excavate insects from deep within trees," Mitchell said. "They must look at a little pinhole and say, There must be something in there—and then they drill it out."

The bounty of birds in Massachusetts, Mitchell said, is noticeably down in the winter. Many do fly south, including almost all the insect-eating birds such as swallows, sparrows, and warblers.

Other birds—such as pine siskins, crossbills, evening grosbeaks, snow buntings, and some blue jays—fly south to Massachusetts from Canada.

Changing Distributions

Birders in Indiana and much of the eastern U.S. commonly associate the arrival of spring with the appearance of robins in their backyards. But Purdue University's Dunning said these birds are no longer a reliable sign of the spring to come. Many stick around all year.

"We have changed the distribution of a number of bird species, because we have modified the environment," he said.

For example, buildings provide increased shelter from the wind, and fruit trees that have been planted throughout suburban landscapes provide food all year. The robin, which lives on fruit in the winter, can now stay put.

Dunning said that many birders in Indiana still believe robins fly south, because they do shift toward out-of-sight habitats along rivers and streams in the early winter.

By the middle of winter, however, the robins have eaten all the berries along the river and are back on lawns eating tree fruits.

So how are folks in the eastern U.S. to know that spring is truly around the corner? Dunning said the appearance of red-winged blackbirds in fields, in marshes, and along roadsides is a more reliable signal.

Red-winged blackbirds stick around much of the eastern U.S. all winter, though they gather in huge flocks around places with lots of food, like grain elevators and agricultural feedlots. "But when the photoperiod starts to change and the days lengthen, the males will leave those flocks and start to claim their territory," he said.

The birds often stake out their territory from power lines or fences, where they can be heard singing a sweet oak-a-lee mating song. Did you hear it today?