Each year a pair of chimney swifts nests in our chimney. We are never sure when they begin building their nest or begin incubating a clutch of anywhere from two to seven eggs. In fact, throughout most of their time with us, aside from seeing them flying into the chimney at dusk, we would never know they were roosting and nesting in our chimney. In fact, it is only after the young have hatched do we begin hearing twittering sounds coming down the chimney.
In spite of the fact that chimney swifts live in close proximity to humans, we know very little about them. This is large because they spend their days flying about catching insects. In addition, they nest in chimneys that are often difficult to monitor.
For that reason, it is not surprising that my wife and I do not know when they begin nesting. If the birds that nest in our chimney are typical, both the male and female build the nest, incubate a clutch of two to seven eggs, and feed the young. At times, an unmated adult will serve as a helper.
The eggs are incubated anywhere from 16-21 days. When the young hatch, they grow rapidly. When the youngsters are around 20 days old some tend to get a little rambunctious and flap their wings while standing on the edge of the nest. Some will even crawl out of the nest and hang on the inside of the chimney.
Finally, when they fledge and leave the safety of the chimney, they form small groups of other fledglings and adults, which eventually form larger flocks before migrating to South America.
The only time we know the young are in our chimney is when the parents return to feed them. On such occasions, they begin rapidly twittering. These sounds increase in volume as they grow. Sometimes we will even hear them begin chattering when we hear a loud clap of thunder during the night.
The sounds are never annoying. In fact, it is pleasing to hear these sounds of nature filtering down our chimney rather than the loud sounds made by vehicles passing in front of our home.
Consequently, when we stopped hearing the twittering of the chimney swifts this past week, we knew they had fledged. Each day since, we have listened in vain for their calling. We now realize we must wait until next summer to be the proud hosts of another family of chimney swifts.
When they departed, I wish they could have taken some of the highway noise with them.