Vennesland, Ross G., and Robert W. Butler. 2011. “Great Blue Heron (Ardea herodias).” 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/grbher3 doi: 10.2173/bna.25