Birds are a diverse group of bipedal animals that span a range of body size, morphology and habitat use. This diversity can be exploited to reveal relationships between morphology, economy and stability of locomotion, providing a complementary perspective to studies of humans and robots. We are conducting comparative studies among birds to investigate the diversity of bipedal locomotion strategies. Our approach integrates terrain perturbation experiments, empirical measures of mechanics and energy cost and simple models. Recent experiments show that both pheasants and guinea fowl adjust stance leg posture, swing leg control and preferred speeds in terrain conditions with differing 'roughness', suggesting that they select among more stable or economic strategies depending on context. Differences in walking and running dynamics exist between these similarly sized birds that may relate to differences in morphology and habitat use. In continuing work we will compare locomotion strategies among ground birds ranging from quail to ostrich to investigate how morphology and body size influence the strategies used by bipedal animals to achieve both economy and robust stability of locomotion.