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 southern boobook is a mainly nocturnal species, though may be active at dawn and dusk. It is heard much more commonly than seen, being particularly vocal in breeding season. The characteristic two-note "boo-book" call or hoot can be heard up to away, the second note generally lower in pitch than the first. Calling takes place from sunset through till dawn, generally with a peak in the two hours after dusk and just before dawn. It can continue for several hours. The male's hooting is higher pitched and of shorter duration, and is heard much more commonly than that of the