Are rhea more aggressive than the general bird species? If a rhea is left alone, will it attack a person? What about if a rhea is near their young?

Rheas are generally not aggressive towards people unless they feel threatened. Some birds will attack if they feel their offspring are in danger. However, very few people have ever been attacked by these tall and powerful birds.

The only reported attack happened because a worker was trying to catch a pair of rheas during breeding season, so the male was in an extremely protective state. He jumped up and kicked the worker with both legs, causing him to fall over and be unable to get up for several minutes. The worker suffered some cuts and bruises but was otherwise okay.

Another report of an "attack" was actually defensive behavior on behalf of the bird toward its eggs or chicks. A young rhea, not much bigger than a chicken, charged at a farmer who was walking through his field. The farmer thought he would teach this little bird some manners by throwing rocks at it until it stopped charging him and ran away instead of standing its ground like most adult rheas would have done when confronted with danger. Although this sounds like an attack by any definition

Are Rheas Aggressive?

Rheas are aggressive. I have seen it first hand when an upset female chased me down, attacking with her beak and talons. I am sure you would not want to pet them like chickens, but their aggression is generally directed at other rheas.