Skulking or supping?

Meet the Common Yellowthroat, AKA Geothlypis trichas, spotted yesterday amongst the foliage on a scrub hawthorn in my upper meadow. I walked up there looking for butterflies and saw an indigo bunting on the way but couldn't catch any decent shots until I stalked the source of a persistent "chip." Mr. Common Yellowthroat was nearly invisible among the yellowed leaves and gray branches of the hawthorn, but I stood still for a while until the chaotic movement resolved itself into the shape of a bird. And then I snapped.

The Cornell Ornithology Lab's online bird guide
describes the Common Yellowthroat as a "skulking masked warbler of wet thickets" that says "wich-i-ty, wich-i-ty, wich-i-ty." I didn't hear any witchity sounds and I don't recall ever seeing this bird before, but on the wing he's easily mistaken for a goldfinch, of which we have bazillions. The Common Yellowthroat's calling card is that distinctive black mask, which goes so well with the word "skulking," although he didn't appear to me to be skulking. He appeared to be snapping at insects and swallowing them for supper.