The sounds made by golden-crowned kinglets are so high-pitched that many people can no longer hear them (a good reason to get a-birding before retirement age). If you can hear them (and thankfully, I still can) you will always know when they are visiting your neighborhood even if they are too far up the tree-tops to see. Of course, sometimes they just make a high-pitched racket, as in the video below (very brief glimpses of the birds themselves, primarily just a sound document).
[My fear, of course, that I'm not actually hearing all there is to hear in this clip!]
In other Charles River Peninsula news... There are currently more than a dozen wood ducks in the river around the peninsula. They seem to be observing an uneasy truce with the mallards. This morning, in addition to the normal wood duck scream, I heard one make a sound more akin to a howl (sadly unrecorded).
Also, there was a brief visit by a small group of rusty blackbirds. They are such active and (in my limited exposure to them) jubilant birds. I always feel a twinge of pathos, like they are the remnants of some formerly great but now doomed and scattered tribe.