Genocide is "the deliberate and systematic destruction, in whole or in part, of an ethnic, racial, religious, or national group". Animals do not commit genocide. PERIOD. A lion might kill another male to take over its pride, but it won't partner up with other lions to deliberately wipe out another group.
Skirmishes between animals are very localized and focused on "survival of the moment." There is no long term deliberation possible, which is what is required when enacting genocide.
When a lion takes over a pride, he kills all the children of his predecessor, on purpose. That maximizes his own reproductive success.
Another example that came to my mind is that race of Japanese Hornets that systematically massacre beehives. They attack and kill every. single. one. of them. And then
they steal the larvae.