Vulpin pack/riding ostriches - BtWD

In the world of Beyond the Western Deep, all mammal "races" are sentient people. Fish, birds, and insects fill the role of "animals," and fill the roles of everything from fodder to rare and dangerous monsters.

The desert-based vulpin (fox) people keep ostriches as pack animals. The common form is too small to seriously consider as a mount, but richer families have the means to develop and keep larger breeds that can carry riders.