A review of current knowledge concerning the breeding and summer distribution of the Cordilleran Flycatcher (Empidonax occidentalis) in Mexico

Harold F. Greeney, Matthew J Miller, Charles Van Riper, Occasional Papers of the LSU Museum of Natural Science (89) :1- (2018).


The Cordilleran Flycatcher (Empidonax occidentalis) is one of many North American birds whose distribution crosses the US–Mexican border and for which little is presently known about summer distribution and breeding biology south of this border. In addition, the Cordilleran Flycatcher presents ornithologists with a number of challenging questions surrounding its taxonomy, migration, distribution, population structure, and species limits. In particular, there remains a good deal of uncertainty concerning the species-level relationships, seasonal movements, and the wintering and breeding distributions of both recognized subspecies of Cordilleran Flycatcher in Mexico. Using field observations, a thorough review of the literature, and the examination of several distributional databases, we compile current knowledge on Mexican populations during the summer months and emphasize directions for future research. We document the northern limit of confirmed breeding Cordilleran Flycatchers in Mexico and point to gaps in our understanding of its summer range south of the US border. Currently available data point to a potential migratory divide in northern Mexico, which has implications for species limits and evolutionary dynamics within the Cordilleran Flycatcher.