Axe-Beak Riding Birds

Axe-beaks are a species of huge flightless birds which have been tamed by the sab'rones, or gaucho cowboys, of the Drylands. They are known colloquially as terror birds, and stand taller than a man. They are easily large enough to ride once domesticated.
Despite being flightless axe-beaks can run as fast as a horse across the open grasslands, without needing as much water or being at the same risk of broken legs from hidden potholes or obstructions. When running, their heads dip low in line with their bodies and their necks and wings stretch out to stabilise themselves, almost gliding over the ground. Thus steadied, their bodies move very little in comparison, resulting in a remarkably smooth riding experience.
The birds are carnivorous, eating everything from small animals to carrion and even hunting in packs to bring down larger animals. Their beaks have toughened hook-like tips on the upper and lower surfaces, which they use both to smash open the burrows of prey and to club and hook the larger animals they hunt.
A terror bird will bond with a sab'rone as a chick, and is then raised in preparation for their future life as a riding bird. They only willingly partner with one rider, although it is possible with careful training to raise an axe-beak which will accept other riders. When being ridden by the sab'rones, the axe-beak is fitted with a special saddle that holds the rider in position while allowing the bird to move its body and wings freely.
Sab'rones are a relatively common sight in the grassy plains of the Drylands, although it is always impossible to know whether a group of riders on axe-beaks are cowboys or brigands, as they are frequently both. Clad in long thin leather coats that protect them from the heat and infrequent rains, and wide-brimmed hats that shelter them from the scorching rays of sunlight, a group of axe-beak riders is a distinctive sight. When they spot their prey, they will urge their birds into a sprint as they swing bolas, lariats and nets to entangle whatever they are hunting - whether it be animal or human.

Axe-beak riding bird by Geoff Hancock