The structure and topography of pelvic bone in polar owl

The research suggests that five lumbar vertebrae in polar owls, which are firmly fused with each other and with the sacral bone form the vertebral-sacral bone, which stiffens the spinal column and supports the pelvic limb. The polar owl has a rectangular pelvic bone, slightly expanded in the caudal direction. It consists of the ilium, ischium and pubic bone, which are fused together at the level of articular cavity. The ilium consists of a larger preacetabular part which extends from the cranial end of the bone to the articular cavity and a smaller postacetabular part which is located behind the articular cavity. The ischium consists of a body and a wing. A long, saber-shaped pubic bone consisting of the body and the tail grows to the wing of ischium. The tails of pubic bone directed caudomedially to each other. The total length of vertebral column in female polar owl is 1.15 times greater than male one. The iliac-ischial opening is located behind postacetabular part of ilium and ischium wing. A locked opening is cautocentral to the articular cavity between ischium body and pubic bone tip. Vessels and nerves for the pelvic limbs pass through this opening. Relative length of the pelvic bone in relation to the length of the body is 30.2% (male) and 26.7% (female). The ilium occupies 35.6%, ischium - 17.5%, pubic bone - 27.1% and sacral bone - 19.8% (male), 36.2, 18.1, 26.6 and 19.1% (female), respectively.