In birding lingo, a summer resident is a bird that arrives in spring, breeds and departs in the fall for southern climes or lower elevations, escaping the harsh winter conditions. Most summer songbirds feed on insects or nectar and must leave before cold weather kills off their source of nourishment. In the Midwest, the majority of summer residents arrive in April, after the risk of a hard freeze has passed. Two exceptions are the eastern phoebe and tree swallow, which turn up during the latter half of March.
Tree swallows usually arrive in large flocks, gathering in bottomland woods along our lakes and rivers. Identified by their blue-green back, white underparts and slightly forked tail, these insectivores will soon pair off and look for a tree cavity in which to nest; some will use bluebird boxes or other man-made structures. Eastern phoebes, which look like miniature eastern kingbirds, take up residence along streams and wetlands, flycatching from saplings or from limbs that overhang the water. Both birds rely on the moderating effect that streams and lakes have on air temperature, allowing insects to remain active on cold March days.
