I have heard people on here say zebras are aggressive in captivity, yet I've seen all three species mixed with other savanna species in zoos during my visits. The Como Zoo has plains zebras in with kudus and sulcata tortoises, Henry Doorly has Grevy's in with ostriches, and the Hogle Zoo has mountain zebras in with giraffes and ostriches. In all of these the zebras and other animals seemed to keep to themselves. I know this is only three different collections and not multiple viewings, but the animals all seemed to get along. Is it just that some zebras are aggressive? Do they have to be gradually introduced to the herd?