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
Anatomical terms of bone a condyle, particularly the medial epicondyle of the humerus. These terms derive from Greek. An "eminence" refers to a relatively small projection or bump, particularly of bone, such as the medial eminence. A "process" refers to a relatively large projection or prominent bump, as does a "promontory" such as the sacral promontory. Both "tubercle" and "tuberosity" refer to a projection or bump with a roughened surface, with a "tubercle" generally smaller than a "tuberosity". These terms are derived from "Tuber" (). A "ramus" () refers to an extension of bone, such as the ramus of the mandible in the jaw