Aquila is one of the Giant Eagle at Camp Jupiter.
The Trials of Apollo
Camp Jupiter Classified: A Probatio's Journal
As Claudia, a new arrival at camp, leaves a bag of elephant droppings to be picked up, the eagle picks it up, along with the legacy of Mercury, as she drops the bag at the dump before returning to camp and gives Claudia a nudge as thanks for accompanying her.
A couple of weeks later, Claudia sneaks in the aviary to take her on a reconnaissance flight before her plan goes into motion, however Reyna Ramírez-Arellano stops the legacy of Mercury before she reaches her. The following day she and Frank go with another eagle to extract Claudia, Janice, and Blaise from the dumb after they find the ancile.