Empathy and anthropomorphism, well-established components of the human-pet relationship, are considered to be especially related to pet animal welfare. We have developed a systematic and standardised approach to explore the effect of the human-pet relationship on animal welfare, focusing on pet birds. Based on a data set measuring the owner-bird relationship as well as bird welfare, cluster analysis and multivariate regressions were used to identify empirical types of bird owners and analyse their effect on bird welfare. Five empirical types of bird owners were identified based on the multi-dimensional relationship between owner and bird which consisted of: (i) the closeness-appreciating anthropomorphising owner; (ii) the closeness-appreciating socially supported owner; (iii) the anthropomorphising socially supported owner; (iv) the inattentive owner; and (v) the distance-appreciating owner. These differed in terms of the owner's tendency to anthropomorphism, the social support the bird provides to the owner, the empathy, attentiveness and respect of the owner towards the bird, and the bird's relationship with the owner. In particular, the inattentive type, but also both anthropomorphising types, raised serious questions as to the well-being of the pet bird. We found significant correlations to bird behaviour, such as imprinting aspects, aggressiveness towards humans, conspecifics and other pet animals, as well as behavioural disorders, such as locomotor stereotypies, courtship behaviour towards humans and feather-plucking.