Thick-billed Kingbird (Tyrannus crassirostris) [XC446353]
by Richard E. Webster from Minas Nuevas, \u00c1lamos, Sonora, Mexico (call)
Thick-billed Kingbird (Tyrannus crassirostris) [XC640323]
by Manuel Grosselet from San Pablo Etla, Oaxaca, Mexico (song)
Subspecies
Closest relatives of genus may be Empidonomus and Tyrannopsis. Recent molecular-sequence data indicate present genus is monophyletic and sister-group to clade that includes Empidonomus and Griseotyrannus. There are two main clades within genus, loosely corresponding to "tropical species assemblage" and combination of "W" and "E" species groups of earlier authors, but with some exceptions. On basis of similarities in voice and certain aspects of behaviour, it has been suggested may be most closely related to Couch's Kingbird (Tyrannus couchii), Cassin's Kingbird (Tyrannus vociferans) and Western Kingbird (Tyrannus verticalis). However, this hypothesis has not yet been evaluated with molecular data. Subspecies pompalis weakly differentiated.
The following 2 subspecies are recognised:
pompalis Bangs & Peters, JL, 1928 - South-eastern USA (extreme south-eastern Arizona, extreme south-western New Mexico) and western Mexico (Pacific slope from northern Sonora, western Chihuahua, Sinaloa and western Durango south to Colima).
crassirostris Swainson, 1826 - South-western Mexico (Guerrero, Morelos, southern Puebla, central Oaxaca, south-western Chiapas) and western Guatemala.
BirdLife International Species Factsheet