OCCASIONAL PAPERS OF THE MUSEUM OF NATURAL SCIENCE LOUISIANA STATE UNIVERSITY BATON ROUGE, LA A REVIEW OF CURRENT KNOWLEDGE CONCERNING THE BREEDING AND SUMMER DISTRIBUTION OF THE CORDILLERAN FLYCATCHER (EMPIDONAX OCCIDENTALIS) IN MEXICO HAROLD F. GREENEY1,3*, MATTHEW J. MILLER2, and CHARLES VAN RIPER III3 1Yanayacu Biological Station & Center for Creative Studies, km 5, Via Las Caucheras, Cosanga, Napo, Ecuador. 2Sam Noble Oklahoma Museum of Natural History and Department of Biology, University of Okla- homa, 2401 Chautauqua Ave, Norman, OK, 73072, USA. 3School of Natural Resources and the Environment, University of Arizona, 520 N Park Ave University of Arizona, Tucson, AZ, 85719, USA. *Corresponding author:
[email protected] October 8, 2018 Number 89 ISSN 2474-8935 Occasional Papers Greeney et al. 2 ABSTRACT 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 uncer- tainty 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 sum- mer 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.