Hippo Ganglands (2014)

There's a gang war happening in the Luangwa Valley in Zambia, a battle among hippos for territory, dominance, mating rights, and survival. The reason? Dry season: a seven-month drought that forces over 30,000 hippos to the deepest part of the river to stay wet and cool. Follow these three-ton beasts as they fight lions, crocodiles, and other hippo gangs, struggling to stay alive until the next rainfall. Only then can they return to the lush paradise they once called home

Unfortunately the movie Hippo Ganglands is not yet available on HBO Max.