Songbird migration is like the shaking of an enormous snow globe in which the plastic chips have been replaced by songbirds. One of the first tiny flecks of yellow to settle into the treetops of New England is the Pine warbler. An inconspicuous, unembellished little bird with canary yellow bellow and a dusty green and grey back, they are aptly named and spend the day catching insects from the tops of conifers. Two white wing bars and a loud monotone song are subtle giveaways to identifying the Pine warbler. Listen for the slurry trill from high in the tree tops , a much less mechanical song than the insect like buzz of the Chipping sparrow.