Birds live in almost every environment; they fly, run, swim, dive, and climb. Recently, it has been suggested that an additional, putative mechanosensing organ, the lumbosacral (LS) ‘organ,’ might contribute to their outstanding locomotor ability. We assume that the LS structure/organ’s functional morphology results from an evolutionary adaptation and correlates with the locomotion modality in avians. The avian LS region shows several unique adaptations among vertebrates; a glycogen body wedged between spinal cord hemispheres, a spinal cord, which is ventrally supported by a denticulate ligaments network. Accessory lobes with potentially mechanoreceptive capabilities protrude into the canal from the spinal cord margins and close to the denticulate ligaments. The LS canal expands near the glycogen body, and the canal’s segments are fused into transverse semicircular grooves at the dorsal side (Kamska et al., in review). We suspect that each locomotion modality requires its own, finely tuned sensor adaptation. Although not yet proven, intraspinal (!) sensor information from accessory lobes would provide the necessarily rapid and sensitive locomotion feedback. Depending on the locomotion mode’s sensory needs, the LS canal and its soft tissue functional morphology would differ, with specific physical attributes pronounced over others. We started collecting data from ground-dwelling, land-fowl, and waterfowl birds. We chose a set of functional morphological landmarks based on the 3D segmentation of the LS canal endocasts and related structures. So far, we have found and characterized large differences between birds with different locomotion habits. We are in the process of establishing the correlation between their locomotion mode and functional morphology.