Kershner, Eric L., and Walter G. Ellison. 2012. “Blue-gray Gnatcatcher (Polioptila caerulea).” The Birds of North America, edited by Paul G. Rodewald. Ithaca: Cornell Lab of Ornithology. Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/buggna doi: 10.2173/bna.23