Wintering Bluebirds--the Magic and the Mystery

As I've watched bluebirds visit my mealworm feeder over the past several weeks, I've realized that this opportunity to observe and recognize members of the family that nested in my nest box this past season, is fleeting, and will never happen in quite the same way again.

The mated pair of my nest box bluebird family was not familiar with a mealworm feeder prior to their exposure this past spring.  They did not approach it or show curiosity at the onset, even though the feeder is very close to the nestbox.  Neither, did they have any experience with a human offering mealworms (nor did I).  It was while watching their behavior as they exited the nest box that I noticed that they sometimes paused on the guard and looked down for insects.  This gave me the idea to place the blue dish of meal worms in their direct line of vision as they rested on the nest guard after feeding young.

It was the female who first discovered the mealworms and landed on the dish with excited chirps, and who readily began to associate the blue dish with mealworms where ever it was placed.  This eventually led her to understand and associate the blue dish in the feeder with mealworms.  The male followed her example.  Very quickly, using fine honed flight skills, the male and female flew into the mealworm feeder's guard with precision, flattening their feathers and barely touching the wire guard that serves to keep out larger birds.

Female adult feeding inside the feeder with young bluebird perched on top.

The first brood juveniles were less precise in their landings and entrance, but also became very adapt at entering the feeder and collecting mealworms both for themselves and to feed to the second brood nestlings.  They also were not bothered by my presence, having seen me many times while in the company of their parents.  I could still distinguish them from their parents by behavior.  The male and female adults both often faced me when they landed, sometimes flying to a closer perch when I was present, and stared at me and wing-waved to solicit more mealworms.  Their bond to me as a potential source of food has remained strong due to their exposure throughout their feeding of two nest broods during the summer.  This behavior sets them apart even now.

The younger bird pictured in the top and third images, finds her way into the feeder, above, and stands alert behind the older female, possibly watching for her reaction or waiting her turn.  Below, a second young bird does not attempt to enter the feeder, but teeters on the outer edge to grab home-made suet that has fallen onto the platform.

Having observed these feeding behaviors and able to distinguish the mated pair from the season's offspring even after the first brood youngsters began to molt and lose their juvenile spots,  I have assumed that the bluebirds now visiting the mealworm feeder are the nest box pair and their offspring.  Since the family left the immediate area after the second brood fledged, I have naturally assumed that the birds having difficulty entering the feeder through the guard are the second brood juveniles that had no opportunity to practice.  

Having said that, last night I opened my new and wonderful resource for bluebird information, Studying Eastern Bluebirds, A Biologist's Report and Reflections, by David Pitts, and began to partially unravel some of my assumptions, or at least cast doubt on them.  As always, with animal and bird observations, we try to make sense of what we are seeing based on what we know about a species or about individuals, but there are many variables and possibilities to consider.  

Some of the interesting information that I read about flocking in Pitt's chapter on wintering bluebirds gave me pause, raising questions but not necessarily answering them.  This is not a bad thing, of course.  Unanswered questions cause us to observe more closely and open our minds to many possibilities.

To summarize, Pitt's winter observations of bluebirds he had banded led him to suggest that each wintering bluebird flock usually contained one adult male, one adult female, and two to six young bluebirds that had hatched the previous summer.  The adults were often, but not always, the mated pair in the territory that included their nest box.  The juvenile bluebirds in a winter flock, on the other hand, were usually not the offspring of the adults in that flock.  However, fledglings from a late nest did sometimes remain with their parents into the winter.  (aha!)

That last statement made me chuckle.  Question answered, question unanswered.  Am I seeing the inexperienced second brood juveniles returning to the feeder with their parents?  Or am I seeing young birds from other local families or migrants that have joined this pair's flock for winter survival?  It is certain I will never know the answer, but it is also certain that I am seeing young birds, numbering four to six, accompanying the familiar adult pair to the feeder, and that all of them are better equipped to survive the winter in the company of each other.

In the last three images, above, you are seeing the same young bluebird attempting to enter the feeder. She ultimately did not go inside, choosing to grab morsels of food from the outer rim, instead.  

More observations on wintering bluebirds and flocking behavior in upcoming posts.  

Links and Resources:

Studying Eastern Bluebirds, A Biologist's Report and Reflections by T. David Pitts

Feeding mealworms to bluebirds
My blog posts on my bluebird family
Bluebird art found on my website watercolor gallery and in my online shop.