Fairly common in dense understory in mixed woods, often near water. Moves quietly, seems to always be peering forward, head stretched in a horizontal position before suddenly flicking its tail upright at great speed. Never lets you get too close and the vegetation is usually too thick to follow. Song is a jumble of twittery notes with a ‘friendly’ quality. Call a tangy ‘tlup.’ ID: Long and slim with a lengthy tail. In all plumages has uniform gray upperparts, yellow underparts with contrastingly white undertail coverts. The dark necklace, bold eyering, and spectacles stand out. Ad ♂ br: striking black necklace and head markings. Fall birds have reduced black, replaced by blue-gray. Ad ♀: little or no black on head; paler streaks on breast. 1st-yr ♂: intermediate between ad ♂ and ♀. 1st-yr ♀: the palest, with only a few faint streaks across neck.