The pervasive influence of human agency on biodiversity in the Anthropocene gives rise to several new challenges for national and international wildlife law, including questions regarding what is natural and what is alien. Ultimately, a new vision and new rules are called for but in the meantime wildlife lawyers and other conservation professionals must work with conventional legal frameworks. Striking instances where vexing issues arise are the recent range expansions of certain canids. Coyotes Canis latrans and crab-eating foxes Cerdocyon thous in the Americas and golden jackals Canis aureus in Europe are progressively colonizing areas and countries where they did not previously occur. A key question is whether to consider this as acceptable extensions of natural range or whether the pioneering carnivores should be viewed as alien species, potentially triggering legal obligations of prevention, control and eradication. In addressing this question we draw on guidance provided under the Convention on Biological Diversity and other international legal frameworks, in which governments are forced to grapple with the application of long-standing concepts to new phenomena in an era of profound global change. Our analysis suggests that coyotes in Costa Rica, crab-eating foxes in Panama, and golden jackals in the Netherlands are not to be considered alien species, whether invasive or not. Thus, even if action to address adverse impacts by these canids on native biodiversity may sometimes be desirable, these species are not subject to legal requirements to combat invasive alien species.