Eastern Bluebird (Sialia sialis)
Common permanent resident throughout all but the southwestern part of the region. Eastern Bluebirds inhabit open habitats, including pas- tureland and savannas. They are also found throughout the year in Pecan bottoms and other riparian woodlands that have a closed canopy and, therefore, do not have an understory. On the southwestern plateau, and locally elsewhere in the region, Eastern Bluebirds are common winter residents and rare and local breeders. They are generally present between late September and early May. Bluebirds are cavity nesters and have benefited from nest box programs undertaken in the region.
Western Bluebird (Sialia mexicana)
Very rare and irregular winter visitor to the western plateau. This species is casual to accidental in the eastern third of the region. When present, Western Bluebirds have not been reported before mid-November. These reports are generally of small flocks with some remaining through early March. These birds are somewhat nomadic and wander locally. They use open habitats such as pastures, shrublands, and juniper woodlands.
