Christmas boobook lores and throat, yellow eyes, legs and feet. It is approximately 26–29 cm in length and 130-190 grams in weight with the female slightly larger than the male. The double-noted hoot, "boo-book," has a clucking quality with the second note usually lower in pitch. The begging call of juveniles is a high-pitched trill. Vocalisations are similar to those described for the Southern Boobook "N. novaeseelandiae" and include individual variation in advertisement calls. This may be useful in estimating owl densities as radio-tracking can be impractical in some terrains. A recording, courtesy of Richard Hill and Owl Pages http://www.owlpages.com/sounds/Ninox-natalis-2.mp3 Its natural
Southern boobook Australia", Gould recognised three species, all of which he placed in the genus "Spiloglaux": "S. marmoratus" from South Australia, "S. boobook", which is widespread across the Australian mainland and Tasmania, and "S. maculatus" from southeastern Australia and Tasmania. Meanwhile, in India, English naturalist Brian Houghton Hodgson had established the genus "Ninox" in 1837, and his countryman Edward Blyth placed the southern boobook in the new genus in 1849. "Southern boobook" has been designated the official name by the International Ornithological Committee. The common name comes from the two-tone call of the bird, and has also been transcribed as "mopoke". William