Relative expression (ΔCt levels) of AR (a), ER-α (b), and AROM (c) mRNA in the cervical, thoracic, and lumbar regions of the spinal cord in male and female golden-collared manakins and zebra finches. Spinal AR expression was higher in manakins than in zebra finches. Within manakins, spinal AR expression was higher in females than in males. Data represent mean ± sem.