During Black-capped Chickadee nesting season (April - July), you can tell alot about what's going on in their lives by what they're carrying in their beak. Here's a guide to some of the stuff you might see them carrying and what it might mean.
If you see a chickadee with a beak-full of wood chips, they are in the early stages of clearing a potential nest cavity. If you put out a nest box for the chickadees, put an inch or two of wood chips in the bottom of the box and you'll even see them carrying chips out of an artificial cavity.
If you see a chickadee carrying strands of moss, it may have started to build a nest within a cavity. This moss base may include other fibrous materials as well. I've seen them taking fibers out of our coco doormat to add to their nest!
ANIMAL HAIR AND FIBER
When you see a chickadee carrying a beakful of animal hair, they may be putting the finishing touches on a nest. This lining of soft material will nestle the eggs and eventually the nestlings, helping to keep them warm. You can offer alpaca fiber, sheep wool, or even dog or cat hair.
Chickadees will sometimes start or even complete a nest and never use it. So watch for these other beakfuls to see if you really have an active chickadee nest.
See a chickadee take a juicy green caterpillar into a cavity and - lucky you! - there's a good chance you've got eggs and maybe babies!! While mom is incubating eggs, dad brings her food. Sometimes she'll come out to get it, or else he'll bring it in to her. Then, after the eggs have hatched, insects make up the nestlings' entire diet.
This stage is fairly easy to observe since parents get pretty busy providing insects for their rapidly growing young. You'll be able to enjoy this activity for about 28 days: 12 days of the female being fed by the male during incubation and 16 days from when the eggs hatch to when the babies are ready to leave the nest.
If you see a chickadee exiting a nest with a dark-and-light blob, they're doing a little housecleaning. They're cleaning a tidy sack of poop, called a fecal sac, that has been left by a nestling.
Chickadees are so common in backyards that it's easy to observe their nesting activities if you take the time. See if you can follow their progress through each of these steps in the process. Have fun but be careful you're not disturbing them!