The giant eagle is a magical beast. As its name fairly obviously implies, it is a giant version (10 feet tall with 20 foot wingspan) of a regular eagle. It is also a lot more intelligent. They have superior vision capable of seeing prey miles away.
Giant eagles, like many similar creatures, are prized for their value as aerial steeds. To tame one, the eagle must have a friendly attitude to the rider/tamer, and, being a goodly creature, they must be either good or neutral themselves. Riding one requires an exotic saddle, and six weeks of training.
Giant eagles, like their smaller kin, are carnivores.
Giant eagles live near great bluffs, cliffs, mesas, or mountain crags.
Giant eagles are relatively friendly toward dwarves and elves, and they like aarakocra. Two to twelve giant eagles will typically guard an elven lair. They typically ignore good creatures but attack evil creatures with hostile attitudes. Their intelligence is about equal to that of humans.
Giant eagles are courageous. They fear dark and enclosed spaces, but little else.
Giant eagles speak Auran and Common. Their own tongue is composed of avian cries and gestures.