My backyard has been a busy place lately even though I have warned all humans to stay out of it until the Bushtit eggs hatch. The nest has been relatively quiet with the parents coming and going at long intervals. Sometimes the whole pot from which they have hung the nest quivers and then I know that they are inside. Sure enough a few seconds later one or both will pop out and fly off at great speed.
The activity of which I speak is due to all the migrating birds that have stopped by on their way north. In the last two weeks I have seen six Wilson's Warblers, a Townsend's Warbler and one Cassin's Vireo. And remember, my back yard is teeny, tiny. You have to be quick to see these small birds. They don't stop for long although they are usually ravenous and will not pay too much attention to humans as they scour the bushes for something to eat. The Vireo looked like he was literally blown in on the wind. He landed upside down, righted himself and was off.
Warblers are such pretty little birds and are still very wild. They will not allow themselves to be domesticated in the slightest. Their colors range from very bright yellow (like the Wilson's) to contrasting black and white to blues, greens, and grays. Here is a link to Giff Beaton's page of Warblers. He has a ton of photos and you will find the Wilson's down at the bottom. I have never gotten a photo of one of these fast-flitting birds. I consider myself lucky to grab them with my binoculars long enough to make an identification. You won't find the Townsend's Warbler on his list, so here is a link to the Cornell Laboratory of Ornithology's site that shows this striking bird.
Of course, warblers are named warblers because of their beautiful song and are sometimes just called songbirds. But you won't hear them singing during migration. It's only when they get to their breeding grounds that the males will burst into song to attract the females. One year I was fortunate to be in Canada (Montreal) in late May, just in time to see all these birds arriving in great numbers to set up housekeeping and was able to hear them sing.