The Thick-billed Kingbird is a loud and conspicuous inhabitant of open wooded habitats that predominantly occurs within a narrow range in western Mexico. On 4 June 1958, in the Guadalupe Mountains of southeastern Arizona (8 km north of Sonora and 1.6 km from New Mexico), John and Seymour H. Levy found a pair of Thick-billed Kingbirds ( Levy 1959 ), the first documented occurrence of this species breeding north of the U.S.–Mexico border. Since that time, the Thick-billed Kingbird has become a fairly common, but localized, breeding species in southeastern Arizona ( Corman 2005i ), that also occurs in extreme southwestern New Mexico ( New Mexico Department of Game and Fish 1996 ). In southeastern Arizona, the species typically occurs along perennial or intermittent streams and rivers with broader floodplains, near riparian woodland edges and clearings with large sycamores (Platanus) and/or cottonwoods (Populus) ( Corman 2005i ).
Like other kingbirds, this species forages in open habitats and captures insects on aerial hawking flights. The Thick-billed Kingbird "makes a big show of each food-capturing flight, quivering the wings and keeping the head feathers erected" ( Phillips et al. 1964a : 79), with much vocalizing. The species typically builds its nest in inaccessible locations in tall trees, and detailed studies of its breeding biology are lacking. Indeed, little has been published on almost every aspect of this species' life history. The most extensive source of published material on the Thick-billed Kingbird is that of Smith 1966d , who provided a mere 6 pages of text (in his 250-page monograph) based on observations of 5 males (1 paired) made over 3 days in southeastern Arizona and northern Sonora in June 1962. This limited record of displays and vocalizations of this species was set against a more extensive examination of the Eastern Kingbird (Tyrannus tyrannus) in his survey of Tyrannus vocalizations and behavior.
Despite the paucity of published information on the Thick-billed Kingbird, much of this species' biology is likely similar to that of other kingbirds: Cassin's Kingbird (T. vociferans; Tweit and Tweit 2000 ), Tropical Kingbird (T. melancholicus; Stouffer and Chesser 1998 ), Couch's Kingbird (T. couchii; Brush 1999a ), Western Kingbird (T. verticalis; Gamble and Bergin 1996 ), and Eastern Kingbird ( Murphy 1996a ).