This little chickadee will stash away as many as 80,000 seeds for winter survival.
Photo: NASA
By Kevin McKeon, Maine Master Naturalist
Our state bird (and that of Massachusetts) is the black-capped chickadee, Poecile atricapillus, a non-migratory perching bird that lives here year-round. They’re common visitors to bird feeders, but their chicks require insects and caterpillars for growth. A pair of chickadee parents needs up to 9,000 protein-rich caterpillars to raise a single brood of chicks! They also eat ants, beetles, aphids, millipedes, snails, and wild fruit — and especially spiders, for a rather interesting reason noted below. Chickadees have excellent catching skills and they need it, eating about 20 times more food in winter than in summer to survive. A consistent food source, like a bird feeder, can nearly double a chickadee’s winter survival rate. As winter approaches, they’ll tend to form small flocks, darting about evergreen thickets eating seeds and insect eggs, then huddling together in a shared backyard bird box or sheltered tree hollow to conserve heat. During our trail walks, sitting still for a few minutes will often attract these curious little chirping birds, wondering what creature ventures into their evergreen-thicket world.
A group of chickadees is called a “banditry,” referring to their black “bandit” masks and to their bold, curious nature. North America holds seven species of chickadees. In the lower 48 of the United States, it’s usually the Carolina chickadee in the Southeast, or the black-capped chickadee in the North and West. In Europe and Asia, there are eight more chickadees, but folks there call them tits. The oldest known chickadee lived for about 12½ years, but they average about 2-3 years. Young chicks and eggs experience high mortality from owls, hawks, and tree-climbing mammals that will invade their nests. Chickadees prefer making use of old woodpeckers’ nesting holes in trees but are able to dig out their own holes in the softened wood of valuable forest snags. A backyard birdhouse is an especially good find for a nesting pair; plans for bird nesting boxes are free here, and make an easy winter project. They’ll cozy the place up with animal fur, mosses, lichens, and other soft plant materials.
Six to eight eggs hatch and about a week or so later, the chicks fledge — but are still not quite independent, relying on parental feeding for another two to three weeks. At about 5-6 weeks old, the chicks fly off to form flocks and hone their insect-catching skills. As mentioned above, spiders are a favorite food, and for a rather unusual reason: These arachnids contain high concentrations of taurine, an amino acid vital for neurological growth and development. This growth happens within the chickadee’s hippocampus — a development crucial for the formation of the bird’s wondrous brain growth and an important aspect to their winter survival, but not the only one.
Chickadees, like many other overwintering creatures of our forests, store huge amounts of food for winter survival — up to 1,000 seeds and insects a day and 80,000 during the fall hoarding season — hiding them under leaves, tree crevices and loose bark, amongst evergreen needles, and other such spots. To remember these spots, their brains undergo a type of neurogenesis — an expansion of their hippocampus, the brain area responsible for memory. An approximate 30% brain growth happens every fall, and the taurine from spiders is a key nutrient for this growth, with research suggesting that brain neuron generation also happens, allowing the recall of specific food storage spots — and once used, these neuron storage “bits” in their brains are removed. This growth and brain activity is maintained throughout winter’s challenging weather. Then, when spring’s warmth brings out the bugs, memory is not needed as much and our chickadees’ brains return to their summer size!
During winter nights, chickadees seek out enclosed, wind-protected spaces — again, tree cavities or bird houses — where they’ll use a physiological adaptation whereby they enter a short-term hibernative state — a controlled hypothermia and respiratory condition called torpor, when they’ll lower body temperature by about 20º and reduce metabolism and energy needs, enabling endurance of extreme cold temps. During less cold times, their shivering (thermogenesis, or“heat creation”) and huddling generates and conserves heat; their insulating feathers also help. During winter, our little bird will gain up to 10% of its body weight in a single day, burning up these reserves shivering during the night, and gain it back again the next day. So, it’s easy to understand how the black sunflower seeds in our backyard feeders, kept clean, and help these bandits survive.
Now a little about taurine, its effect on memory, and its benefit to our state bird’s winter survival. So, are there really that many spiders around for all our chickadees to eat? Well, estimates vary quite wildly, but most researchers seem to agree on about 10,000 spiders per acre of forest, and 2 million in an acre of meadow! Also, spiders and insects make up about 80% of our hummingbirds’ diet — yet another reason to relegate a part of our lawns to a “no mow” status and letting nature form a nice little meadow for our little critters to flit about, and for us to enjoy watching!
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