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I hatch a strategy to keep chickadees in the garden year-round

I’ve been watching the chickadees at my feeder this winter. It's been easy to attract them to our garden with a feeder stocked with sunflower seeds. And as I daydream about impending spring, I’m wondering how I can encourage them to stay here all year. They seem to disappear come spring, and I wonder why there isn’t a pair of chickadees in every backyard.

Chickadees are a woodland species but Toronto boasts 3 million trees, and my backyard has several large maples, so its not simply a case of inappropriate habitat. Or is it? There are a number of features of the urban forest that are different from a natural, climax forest, preferred by chickadees and other insectivores such as nuthatch and woodpeckers. Viewed from the air, the tree canopy in Toronto appears c lose knit in many neighbourhoods. But in gardens and streets, the shrub layer and the herb layer are mostly missing, so the vertical structural complexity of the urban forest is simplified. The urban forest is managed. A managed forest has no old, dead trees that harbour bugs and diseases, which in turn support birds. The urban forest is young since most of the original cover was cut and burned off 200 years ago, and only replanted in the last 60. A young forest does not have fully developed canopies, or the gnarled and tangled branching, critical for nesting, protection and climate amelioration in winter. The urban forest is comprised of many non-native tree species such as Norway maple, Honey locust and Siberian Elm. These imported species do well here because they are “released” from many of their natural enemies here, but the flip side of this is that they harbour fewer bugs that birds find delectable.

So perhaps the answer to why there isn’t a chickadee pair in my backyard, or in every Toronto backyard simply reflects the fact that any one backyard does not provide enough resources alone to satisfy a chickadee family. A single family needs a home range of several blocks perhaps to survive and breed. Given that, then, how might I attract the chickadee to at least nest in my backyard, and that way I get to see them every day at least part of the time.

Build it and they shall come

Chickadees are hole nesters, or more correctly secondary cavity nesters. They use existing holes in trees as nest sites. Natural tree cavities are scarce in the urban forest for a number of the reasons touched upon above; trees develop holes when they become old and diseased, or after they lose a limb to a storm or a chainsaw and the joint doesn’t heal completely. In the urban forest, old standing trees are considered a hazard and are felled, and young managed trees haven’t yet developed cavities.

Fortunately, it turns out that chickadees will also use artificial nest sites provided they have the key characteristics: an entrance hole that is snug and not too big, else it let in other cavity-nesting birds or worse still predators. And a lining of woodchips, just like the inside of a real tree hole would have. A strategy is emerging: I will erect nestboxes in the garden in an attempt to attract the chickadees to nest.

Next week: I have a (nestbox) plan

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