What large mammal species both take part in caring for their young?
Lions, ostriches, wolves, most other canids like jackals and foxes. It depends how large you mean by large, really. I’ve never heard of rhinos staying together after mating, though. EDIT: Oops, yes, ostriches are birds – I was just thinking of animals rather than mammals specifically. It’s a myth that male lions don’t hunt, though – the females do do most of it, but the males sometimes join in. I’ve seen two male lions and four lionesses kill a buffalo together, for example. You’re right that male lions aren’t always on parenting duty, but they do play a part in their offspring’s lives, unlike other cats. They protect them and play with them and so on. I’ve done a little research and found some more mammals in which both parents rear the young, though they’re not exactly large – marmosets, beavers, and klipspringers. There’s also animals that live in groups of males and females, like buffalo, so the baby has both parents present, though the male doesn’t usually do anything to help rais