How do birds choose a place that will allow them to keep their chicks safe from the time the first egg is laid until the last fledgling flies away? For chickadees, including the Black-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (Poecile carolinensis) that I studied in Pennsylvania, the answer lies in tree trunk cavities which they will find and excavate for their nests. This made them convenient for my study, because they will readily use artificial nest boxes resembling dead trees, allowing me to easily monitor the whole breeding cycle from nest construction, to egg laying, to brooding, until the nestlings are ready to fledge!
A tree hollow is a great place for a nest, being sheltered from predators and the weather, and chickadees maximize coziness by lining their nests with moss, plant fibers, and fur. But where do they get fur? These daring little birds pluck fur off of mammals much larger than themselves, including squirrels, rabbits, deer, and even dogs. A cozy, secure nest helps the mother incubate and protect her 5-7 eggs (or, rarely, 9 or 10 eggs) while her mate brings back food for the family, such as insects.
The gaping golden maws and bulging, blind purple eyes of the day-old nestlings (pictured below) might not appear very appealing, but to a chickadee parent, the sight and sound of begging nestlings is irresistible. With so many siblings competing for space in the nest, they tend to arrange themselves in a tidy circle. Each baby chickadee’s beak points upwards so that when mom or dad returns with a tasty caterpillar, they can swiftly open wide and begin the begging ritual. The mother will stuff those yellow mouths with food until the nestlings have opened their eyes, grown in their feathers, and developed their muscles in preparation for flying. Almost magically, a chick transforms from a gooey pink gummy bear-sized blob into a fledgling the size of an adult bird in just two weeks. These fully grown fledglings, nearly ready to hop out of the nest and fly away, certainly look much cuter to us humans!
Below: The same nest as eggs (Left) and newly-hatched birds (Right).
Photos and caption by Clay Jones
Edited by Brady Nichols