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
Norfolk boobook km²) Mt Pitt section of the Norfolk Island National Park. Boobooks breed in tree hollows. Recorded clutch sizes from Norfolk Island range from one to three eggs, with two being usual. Boobooks feed on small vertebrates, especially birds and mammals, as well as invertebrates. The population of the Norfolk boobook declined with the clearance and modification of its forest habitat, especially the felling of large trees with suitable hollows for nesting in. There was also competition for nest hollows with feral honey bees and introduced crimson rosellas. By 1986 the population had been reduced to a single female bird, named