The ultimate form an organism attains is based, in part, on the rate and timing of developmental trajectories and on compensatory relationships between morphological traits. For example, there is often an inverse correlation between the relative size of an organism’s head and the length of its legs. Avian examples with disproportionately small heads and long legs include ostriches (Struthionidae), flamingos (Phoenicopteridae), cranes (Gruidae), stilts (Recurvirostridae), and storks (Ciconiidae). To determine whether a possible compensatory relationship exists between relative head size and hind-limb length in a typically long-legged family of birds—the Ardeidae—we measured skull dimensions (length, width, and height of cranium, and total skull length, including culmen) and skeletal hind-limb dimensions (femur, tibiotarsus, and tarsometatarsus) of the 12 North American species (north of Mexico) and of 12 additional taxa, including the morphologically divergent Agamia and Cochlearius. Our analyses reveal a negative allometric relationship between head size and leg length. For example, Ardea species exhibit the smallest relative head sizes and the longest legs, while Butorides, Nycticorax, Nyctanassa, and Cochlearius have among the largest heads relative to hind-limb length. Furthermore, both positive and negative allometries occur in paired comparisons between the three hind-limb bones, resulting in tall morphotypes having disproportionately short femurs while small morphotypes exhibit long femurs; this relationship has implications for foraging behavior. Moreover, long legs of Ardea apparently derive from an extended growth period, or hypermorphosis, while relatively short legs of Butorides result from growth truncation. The latter are thus morphologically paedomorphic features that, paradoxically, permit a functional precociality of the hind limbs: early onset of prehensile ability of the feet for grasping branches, which nestlings retain into adulthood, later expressed in foraging mode. This developmentally accelerated prehensile function in small species may be attributed, in part, to selection for predator avoidance in the early nestling stage.