During the winter, when the Yellow-rumped Warbler is not in breeding season, it often inhabit resourceful open areas with shrubs or scattered the trees, that can provide it with some source of food supply, such as bayberries and insects, etc. Open areas preferred by the yellow-rumped warbler may include agricultural and residential areas, secondary forests, and shrublands, etc., these habitats generally do not have very dense vegetation; the species can also inhabit forests that are relatively open, such as mangroves, pine forests, and even coffee plantations, etc. The yellow-rumped warbler tends to have more diversified habitats during the migration process, though it is sometimes found in desert areas of the U.S. southwest, it is more common for the species to inhabit alpine habitats during migration as it tends to arid lowland areas.
Both males and females give out alarm calls, but only males sing to advertise territory. Carolina Wrens raise multiple broods during the summer breeding season, but can fall victim to brood parasitism by brown-headed cowbirds, among other species. Some populations have been affected by mercury contamination.
The Field Sparrow’s numbers expanded as settlers cleared forests in eastern North America, but may have declined in more recent times. Despite this, it is a common species with a wide range, and the International Union for Conservation of Nature has assessed its conservation status as being of “least concern”.
The Song Sparrows forage on the ground, in shrubs or in very shallow water. They mainly eat insects and seeds. Birds in salt marshes may also eat small crustaceans. They nest either in a sheltered location on the ground or in trees or shrubs. Song sparrows with areas of shrub cover in their territory, away from the intertidal coastline, have greater over-winter survival, as well higher reproductive success.