During a NestWatch check last week, I sadly discovered that I had lost a brood of Black-capped Chickadees. The nest was intact and undisturbed, and it contained one unhatched egg and four dead naked and blind hatchlings. I'm assuming it was due to the loss of the mother bird.
The last I definitely saw the female bird was June 4 when she was incubating the eggs and departed during a nest check. She stayed in the area, letting me know her displeasure. The five eggs most likely started hatching around June 6th.
As I think back, I did see some unusual behavior at the nest about 3-4 days before I found the failed nest. A chickadee, which could have been the male, came to the window feeder to gather some mealworms. He brought them to the opening of the nestbox, looked in, then flew to a nearby perch. He returned to the nest hole with the mealworm, looked in, and again flew off to a perch. He did this five times (I thought the behavior was odd and actually counted it out loud every time he visited but did not enter).
I wonder if the female had already perished at that point and the male continued to gather food and look for her in the nest. At that time the four hatchlings could still have been alive, but needed their mother to brood their naked little bodies. They probably died of exposure since they had no way to maintain their body heat without a mother to provide warmth.
The six naked and blind chickadees in another nestbox and six feathered and nearly ready to go chickadees in a third box couldn't lift my spirits after finding the dead nestlings. I couldn't stop thinking about the mama either, and her surviving mate. Any number of things could've happened to the female. But it proves how hard it is out there for a chickadee, especially one putting her all into raising a brood of tiny helpless babies.