Spots and manes: the curious case of foster care between two competing felids

Adoption of unrelated young can have detrimental consequences to the caregivers' fitness in the form of costs emanating from maladaptive altruism. Owing to such costs, complete adoptions and allo-nursing are relatively rare in the animal world, more so between species that compete with one another. Lions and leopards compete through both exploitative and interference mechanisms, resulting in profound aggression and suppression at mutual encounters. Through intensive monitoring, we provide a detailed and prolonged account of a complete adoption of a leopard cub by a free-ranging Asiatic lioness. We briefly review existing literature on foster care in the animal world and suggest that maternal instincts and inexperience, coupled with behavioral and physical resemblance between lion and leopard cubs, could have acted as proximate cues in initiating such an unprecedented association. Furthermore, the unique sociobiology of Asiatic lions wherein the sexes live separately in small groups likely favored the duration of this interaction (similar to 45 d). We also discuss and speculate about broader perspectives of offspring recognition in the animal world and ask whether the study of such important yet rare associations has implications for our understanding of parental care.