Though birds have long been admired by biologists and engineers alike for having “lightweight” bones with specialized “reinforcements,” little work has been done to investigate the internal structure of wing bones. This internal matrix (trabecular bone) is a complex system of struts and plates found in epiphyses across vertebrates. While birds are not unique in having extensive trabecular matrices, they do appear unique in having larger, sparser structures that extend into the diaphysis. Long assumed to act like trusses, these “reinforcing structures” (RS) also seem to be a continuous part of the trabecular matrix, a highly complex structure more akin to a cellular solid. Recent studies model RS in the bird wing as either torsion-adapted ridges or bending-adapted struts. But observations of actual variation in RS across a broad phylogenetic sample of microCT scans shows far higher structural diversity than ever reported. We thus used a holistic, phylogenetic approach to investigate the mechanical role of these structures in the bird wing. Comparative, anatomical samples of bone containing RS were 3D printed and mechanically tested under both bending and torsion, paired with “hollow” versions (RS removed). Initial tests of a small flapping and large soaring species showed no obvious congruence with previous models- both performed better under bending than torsion, and neither showed significant differences in stiffness in hollow vs. intact trials. However, variation in stiffness was significantly lower in hollow than intact samples across both species and conditions. Ongoing work across species will better elucidate the complex mechanical role of wing-bone RS, and along with concurrent analyses on cortical-trabecular tradeoffs, these more holistic approaches will provide crucial insight into the functional morphology of bird flight.