Text and photos by Noreen Hannigan
I learned from renowned entomology professor and author, Doug Tallamy, that native host plants are critical sources of insects for birds to feed their young. One of the earliest Continuing Education events I can remember attending after I graduated ARMN training in 2015 was a talk by entomology researcher Desiree Narango. Her graduate study (with Doug Tallamy as her advisor), discussed how the availability of native plants in residential landscapes influences the nesting success of Carolina chickadees (Poecile carolinensis). She found that if there was less than 70% native plant biomass, insect populations declined as well as the chickadee population rate.
I walked out of the lecture hall coo-coo for Carolina chickadees and immediately decided to set up a chickadee nesting house. I live on a somewhat busy street in North Arlington in a 1947-era neighborhood. When we moved here in 1982, we took Carolina chickadees, goldfinches, and titmice for granted because they were in abundance. But my ARMN training opened my eyes to how poor the habitat had become, and how many non-native starlings, grackles, and house sparrows had taken over while I wasn’t paying attention.
I doubted my yard had anything interesting for chickadees, but I pressed ahead. Two things I did quickly were: (1) consult Doug Tallamy’s book, Bringing Nature Home, for a tree that would fit in my small yard and support a decent number of caterpillars, and (2) head to a bird store for a chickadee house. Within a few days of hearing Ms. Narango’s talk, I planted a river birch (Betula nigra) and installed the chickadee house. Then I waited for the avian real estate market to get active in early spring.
Carolina chickadees are year-round residents and live in flocks for much of the year. In late winter, nesting pairs (who are thought to mate for life) break off and look for nesting sites in natural cavities such as holes in decayed trees, but they will also use man-made bird houses if they are 5-15 feet above the ground and built to the right dimensions. Houses for many kinds of birds are commonly sold in bird stores, or you can make your own. Be sure, though, that you buy or make the right house for the bird you want to attract (and watch out for pushy house sparrows). Bird houses are easy to make if you are reasonably handy and have some basic tools. If you are going to make your own house, be sure to use the suitable dimensions and untreated wood.
You can learn more about Carolina chickadees and nest boxes and from websites I consulted, such as Cornell University’s “All About Birds,” and the Tennessee Wildlife Resources Agency site. Because I was impatient, I bought a ready-made chickadee house from a local bird store and—because I wanted to place it where I could see it from my porch—I also bought a mounting pole to put it in view.
I put it up in late winter so any chickadees in the area could scout it out before breeding season. Perhaps I overthought the process, but I worried that the house was too exposed to the elements, so I bought a wrought-iron arbor kit that I assembled and placed over the pole-mounted house. Then I planted a crossvine (Bignonia capreolata), which is semi-evergreen, to provide some protection in spring. It took a couple of years for the crossvine to get established, but it is growing over the arbor now and is casting shade and protection from the rain, as intended. (Yes, I have to keep it trimmed.) The cross braces on the arbor have also provided places for the adults to perch as they go in and out with nesting materials and food for the nestlings, which affords me the ability to observe them better.
The choice of the river birch proved to be a good one. Doug Tallamy lists river birch among the top five Lepidoptera (butterfly and moth)-supporting trees. Indeed, it has proven to be a popular perching and foraging place for chickadees and other birds in my yard. It is a fast-growing species, so it only took one or two years to attain a good size and be discovered by many birds. While nesting, the chickadees fly straight to it dozens (hundreds?) of times a day to peck at the peeling bark and branches to find insect protein for their nestlings. I cannot always see what they are finding on the tree, but they never seem to come away empty-beaked. Bonus: Goldfinch couples are also attracted to it and love to eat the seeds off the catkins (drooping flower clusters produced by trees) in late spring.
Nesting chickadee couples start looking for nest sites around early April. I see them visit the yard, call to each other, and inspect the bird house. Like any landlord, I eagerly anticipate signs that a couple wants to sign a lease. Some say it isn’t necessary, but I “prime” the inside of my chickadee house with a couple of inches of wood chips. You can use debris from a decaying tree, or even clean hamster bedding from the pet store. Just be sure the material is untreated. One sign that chickadees are seriously considering your house is when they start throwing out your wood chips. Don’t take it personally, though. Being cavity nesters, they will work on making the interior to their liking and then start bringing in moss and other materials to finish it. After this behavior has lasted a week or two, I gently raise the hinged roof panel (after giving a gentle warning knock) every two or three days to look for eggs.
The next thing I do is somewhat controversial: I put up a “wren guard” as soon as the first eggs appear to keep house wrens (Troglodytes aedon) from getting inside and throwing out the eggs. House wrens are a native species, but they are very competitive for nest sites. They use the same-sized holes and cavities that chickadees do, so they will also be interested in these houses. Some naturalists are opposed to using wren guards and recommend letting the birds work it out on their own. I understand that point of view, but confess I am so intent on boosting the chickadee population around my small suburban yard that I use them.
Once I see the eggs and attach the wren guard, I observe that the parents are momentarily puzzled, but they figure out how to fly around it and into the entrance after about five or ten minutes. Using a wren guard is not a guarantee that a wren won’t get in, but it has worked for me several years in a row. Note that it is important to take the wren guard off when the nestlings are a week or two old (too big for a house wren to pick up) because it will interfere with their fledging. If you chose to use a wren guard, keep track of the timing.
To be clear, I like house wrens and don’t wish to harm or eradicate them. This is their native breeding range, and they are valuable to the ecosystem, too. I merely want them to wait until my chickadees have launched before coming in. House wrens can also take over the nests of other birds such as bluebirds and tree swallows. As this website notes, use of a wren guard should not be your first course of action. The best way to prevent predation by house wrens is to put the nest box away from sites that would be attractive to them. But because of my small yard, I have few options for nest box placement.
I locate my nest box a few yards from my back porch because I’m a nosy landlord and I want to know everything my tenants are doing! While they are feeding their brood of five-ten babies for 16-19 days, they work from dawn until dusk every day bringing in hundreds of caterpillars—thousands before they’re done. The adults are tireless in their parenting duties. In addition to providing those thousands of caterpillars, they also take out all of the babies’ “fecal sacks” (poop in a gelatinous membrane) in order to keep the nest clean. It’s in with food, out with poop, hundreds of times a day for as many as 10 nestlings. That’s an incredible amount of energy and dedication generated by birds that only weigh about a half an ounce.
Whether it would have happened without using a wren guard, I can’t say, but a lot of new chickadees have fledged from my little house. I am usually fortunate to be watching the day they fledge, and I generally count seven or eight fledglings as they emerge. Unlike robin babies that hop around on the ground until they learn to fly, chickadee young take immediately to the air and wait in nearby trees and shrubs for their family to gather. The parents then lead them to a suitable habitat and continue to feed them in the wild for another two or three weeks. Some years I don’t know where they go after they leave my nest box, but this year the fledglings hung around the vicinity for about a month. I watched as they would transit my yard, usually in the mornings, perching from the river birch, to the red maple, to the holly, etc., at first being fed by the adults, but then learning to pick at branches and twigs for their own food. I could also tell as the days and weeks went by how their calls went from squealy little “dee dee dee” noises to more dignified-sounding “chickadee-dee-dee-dee” adult calls.
Lest you feel sorry for the house wrens who had been eying my chickadee house, I came outside the morning the chickadee family had flown, and right before my eyes, a house wren couple was already carrying its own nesting materials in. I let them stay.
Five years ago, I rarely heard a chickadee around my house, but I see and hear more and more with each passing year. Not all survive their first year, but some are thought to live two to five years. Every spring I look forward to nesting season the way some people look forward to baseball season. I get my bird house ready for them and position my porch chair for a good view. Little do they know how much joy they bring. For one thing, they are too busy raising their children and cleaning house!