Where is that found? It certainly implies animals will survive. Humans have lived and admired animals since the dawn of time. Perhaps the Good Lord,knowing that, will let animals survive in order to increase the happiness of the few humans that are saved.
Animals will be in the new heaven and earth.
That’s the “when” of it.
They won’t necessarily “survive”, they will be re-created.
Isa 11:6, BTW.