Whereas the numbers of vertebrae making up different regions of the axial skeleton exhibit substantial variation between major clades of birds, counts of cervical, thoracic, and synsacral vertebrae are relatively constant within major clades of birds. This limited within-clade variability in vertebral number requires that any allometric scaling of vertebral regions be accomplished by differential vertebral growth, rather than variation in somite number. Differential growth of the axial skeleton has been demonstrated in non-avian clades with limited variation in vertebral number, but similar patterns have yet to be documented within major avian clades. Here, I assess scaling of the axial skeleton in herons (Ardeidae), which exhibit a constant number of cervical (17) and thoracic (6) vertebrae across a greater than 10-fold range in body mass. Phylogenetically-informed regression analyses show that the length of the cervical series scales isometrically with body size in herons – a pattern recently demonstrated for crown birds generally – and find that the lengths of the thoracic and synsacral series, as well as the vast majority of locus-specific linear measurements, also scale with isometry. In addition, neck length scales isometrically with skull length and leg length, but shows positive allometry in relation to thorax length. The predominance of isometric growth in herons is consistent with the hypothesis that a pneumatic and lightly built skeleton allows somatic growth to occur without substantial allometric compensation. Future work can test this hypothesis by comparing patterns of axial scaling in pneumatic clades to those of clades lacking skeletal pneumaticity (e.g. penguins; cormorants).