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2. Dense Geographic and Genomic Sampling Reveals Paraphyly and a Cryptic Lineage in a Classic Sibling Species Complex
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4. Hopping, W. A., Linck, E. (2023). Treat Pacific-slope Flycatcher Empidonax difficilis as conspecific with Cordilleran Flycatcher E. occidentalis. Proposal 2023-D-7. Submitted to the North American Checklist Committee. https://americanornithology.org/wp-content/uploads/2023/05/2023-D.pdf
5. Behle, W. H. (1948b). Systematic comment on some geographically variable birds occurring in Utah. Condor 50:71-80.