Thick-billed Green Bittern (Ardetta macrorhyncha) illustrated by Elizabeth Gould (1804–1841) for John Gould’s… https://www.rawpixel.com/image/321760/free-illustration-image-australia-birds-animalsFree Image from public domain licenseLittle Grey Bittern (Ardetta stagnatilis) illustrated by Elizabeth Gould (1804–1841) for John Gould’s (1804… https://www.rawpixel.com/image/321646/free-illustration-image-bird-john-gould-animal-birds-australiaFree Image from public domain licenseMinute Bittern (Ardetta pusilla) illustrated by Elizabeth Gould (1804–1841) for John Gould’s (1804-1881) Birds… https://www.rawpixel.com/image/321339/free-illustration-image-vintage-australia-animalsFree Image from public domain licenseYellow-necked Bittern (Ardetta flavicollis) illustrated by Elizabeth Gould (1804–1841) for John Gould’s (1804… https://www.rawpixel.com/image/321698/free-illustration-image-vintage-gould-illustrationsFree Image from public domain license