When an eagle gets delivered to the camp, everyone has an opinion about what it's doing there. Before long, though, we figure out the eagle is for Serena to train to take care of the rattlesnake problem. We get a glimpse of this when she takes him for a test run:
The eagle settled on the ground with an elegant awkwardness, the serpent still writhing but its movements only a memory of when it had been alive. Serena dismounted and offered the gobbet of meat. The bird released the snake and pounced on the beef. When it finished eating, Serena placed the hood back over the eagle's head. (10.8)
Since the eagle fixes problems for Serena, we get that it's a symbol of her power--if she can train a wild animal, she can do just about anything (even cure herself of nightmares—swing by the "Dreams" page for more on this, though). And boy, does she. It's only a matter of weeks before she has the eagle hunting down rattlesnakes and improving the workers' efficiency and lining her pockets. You go, girl.
The eagle is good news for Serena, showing off her strength and determination to everyone around. But not everyone likes the idea. The workers tell us:
"Everything in the world has its natural place, and if you take something out or put something in that ought not be out or in, everything gets lopsided and out of sorts." (16.26)
The eagle is being talked about literally here, as something that doesn't reside in the area naturally. It's also a metaphor, though, for the workers' concern about Serena ruining the order of things by being too powerful. Not even nature can break her stride—here she brings in an eagle to check the rattlesnake problem and get everyone back on track with their work. And whenever she wants, she subverts natures by having people killed. No wonder the workers are a little freaked out…