The calendar says it is spring, but there are divergent opinions on the matter among the residents of Marjorie’s Garden. The gardener acknowledges that the back of winter is broken, but he will not call it spring until he can touch sun-warmed soil. Mourning doves discuss the matter from the tops of tall pines while a pileated woodpecker jackhammers away on a distant tree trunk and a cardinal sings from the near woods, all sounds that the gardener has not heard in months. And the black-capped chickadees, those small half-ounce bubbles of air covered with feathers, brave the bone-chilling temperatures to work in the sun, pecking at insect eggs hidden under bark and among lichens on the branches of birch and maple.
On a recent morning walk up the lane with Mia the Beagle, I watched a chickadee peck off a bit of lichen and wondered, is the little bird already gathering materials to construct a nest? Back at the house, I rummaged through the basement to find the small wooden birdhouse that was used last year by a pair of chickadees, cleaned out the old nest, and hung the house in the branches of the enkianthus tree, the same branch as last year.
I found no lichens in the old nest. It was constructed mainly of sphagnum moss and lined with hair from our old Brittany, Reilly, who died last year. We had saved her hair from frequent summer brushings for the birds, packing it into mesh bags that we hung from tree branches, not knowing until now that some of it had actually been recycled.
I recently read that garden chickadees seldom use the same nest box twice and
that they prefer to use next boxes that have been packed with wood shavings. Removing the shavings to make room for the nest apparently simulates the excavation of a cavity in an old birch snag, their preferred nesting site in the wild. I plan to give this trick a try with one of the houses we put up this spring, using some of the hardwood shavings that we lay down in the vegetable garden walkways.
All of this brings to mind a chickadee nest box that my father kept in his garden in Columbus, Georgia. It was made from a section of hollow log fitted with a 1 1/4-inch entrance hole and a base plate with smaller drainage holes. He mounted it on a steel pipe, six feet off the ground. Every year for two decades this nest box was used by Carolina chickadees, a species very similar in appearance to the black-capped chickadee, although the two species have been genetically distinct for over two million years. Dad never filled his nest box with wood shavings or even bothered to clean it out at the end of the season. He let the birds do all the work, which they did, year after year. Perhaps location trumps the desire for new digs.
Last year we had to cut down an old arborvitae and I saved several sections of the hollow trunk for birdhouses much like the one in my father’s garden. This summer I will put them up in the back of the garden, at the edge of the woods, for next year’s chickadees, wrens and nuthatches.
We keep the porch feeders filled with black oil sunflower seeds year round and chickadees, along with red-breasted and white-breasted nuthatches, are regular customers, all making continuous runs to and from the feeder, flying off to stash each seed in the bark of a tree or the heart of a leafy lichen. But there are long periods each day when no chickadees appear at the feeders, times when they are feeding on insect eggs and larvae. In spring, summer, and fall, about 80 percent of their diet is composed of insects and insect eggs, other arthropods including spiders and mites, and occasional bits of fat and meat from animal carcasses. In winter, when this figure drops to around 50%, chickadees satisfy their protein needs with insect eggs hidden in tree bark and overwintering larvae on the underside of branches. Thus throughout the year, the garden’s chickadees work diligently at reducing the garden’s population of herbivores.
Are the chickadees that inhabit the garden in winter the same birds that we saw there all summer? Do chickadees migrate? The consensus is that adult chickadees do not migrate, but young birds may move large distances in what are called “irruptions”. So, the loose winter flock of chickadees is likely composed of adults, their young having flown the coop.
Our garden’s flock of winter chickadees is composed of about a dozen birds, each working tirelessly to stay alive, feeding all day, each bird seeking private refuge in an old woodpecker hole or similar shelter at night. A hole the size of a quarter in the side of an old birch snag is sufficient space for a chickadee. Settled in its shelter, it enters a regulated hypothermia, lowering its body temperature to about 15 degrees F below its daytime temperature of 108 degrees F. This allows the bird to conserve about 25 percent of its hourly metabolic energy use when the ambient temperature is at freezing. The colder the outside temperature, the greater the energy conserved.
In late summer, when I find the leaves on the garden’s birches riddled with holes, I like to think that the moth larvae responsible, at least some of them, survived to pupate, and that some of those pupae became egg-laying moths, that the eggs are the overwintering stage, and that one cold sunny afternoon I will spot a few chickadees hopping about the birch branches, stopping to peck awhile at something that only they can see.
Put out a few feeders filled with black oil sunflower seeds and chickadees will find you. They are particularly fond of the tube-type feeders. Hang a suet cake or two among the feeders. But do not despair when they are absent from the feeders for a while. If you look, you will find them hopping about the canopies of garden trees and shrubs, fulfilling their role in the garden food web.