The spring migration of birds washes across our region in a broad swathe that reaches its pinnacle in the middle of May. What started as a trickle as early as the waning days of February builds into a cascade of songbirds, some settling into local breeding territories and others winging on to boreal forests far to the north. Article continues below this ad This population involves thrushes, vireos, orioles, tanagers, buntings – but most of all warblers.