Today I took down the birdhouse to clean out the old nest. The great tits and their offspring left on May 14th and have not returned since (please see the image below). From what I can tell the scale and birdhouse held up nicely. I am also starting to understand the drifting weight values once the birds leave the nest. The nest starts acting more like an obstruction in a clogged pipe (it sticks to the walls) once the birds stop hopping around on top. And this year seems to be a less bountiful season for the birds. The nest is smaller compared to last year and  the drop in weight when the offspring left is also less (I'm guessing fewer hatchlings). I'm kind of curious to see if another bird will start building a nest once I put the birdhouse back up again.