The blue-gray gnatcatcher’s breeding habitat includes open deciduous woods and shrublands in southern Ontario, the eastern and southwestern United States, and Mexico. Though gnatcatcher species are common and increasing in number while expanding to the northeast, it is the only one to breed in Eastern North America. Both parents build a cone-like nest on a horizontal tree branch, and share feeding the young. The incubation period is 13 days for both sexes, and two broods may be raised in a season.
The gray catbird tends to avoid dense, unbroken woodlands, and does not inhabit coniferous, pine woodland. Catbirds prefer a dense vegetative substrate, especially if thorny vegetation is present. Scrublands, woodland edges, overgrown farmland and abandoned orchards are generally among the preferred locations of the catbird. In Bermuda, its preferred habitats are scrub and myrtle swamp. During the winter season, the catbird has an affinity for berry-rich thickets, especially within proximity of water sources.