I find this ranking rankling because it doesn't take into account sex-based differences in monogamous behaviour. For example, the last animal in the list with t

I find this ranking rankling because it doesn't take into account sex-based differences in monogamous behaviour. For example, the last animal in the list with the lowest score (red-tailed fox) is present only because the female fox is indeed extremely promiscuous. Male foxes on the other hand, are almost 100% monogamous, choosing not to mate even if they are widowed. I guess the same also happens for the grey wolf, where pack leaders can access multiple female wolves, which inherently forces the latter into a monogamous relationship.