https://sdakotabirds.com/species/philadelphia_vireo_info.htm
Philadelphia Vireo (Vireo philadelphicus) | South Dakota Birds
Philadelphia Vireo - Vireo philadelphicus - Species Information and Photos - South Dakota Birds and Birding
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https://bcrarebirdrecords.ca/species/philadelphia-vireo
Philadelphia Vireo / Vireo philadelphicus | BC Rare Bird Records
An updated comprehensive online database for rare birds of British Columbia
philadelphia vireorare birdbcrecords