Zeta's eagles, like all eagles, are capable of flight, unlike other Birds. They are of varying sub-species of eagles, with no two looking exactly alike. They are not as intelligent as Zeta, and some of them do well than others. They also work under the threat of being punished by Zeta for any failure, with Steve being made an example of.
After being spurned by Mighty Eagle, Zeta retreated to an arctic island called Eagle Island and began constructing an arctic resort with a group of eagles, after gathering riches and technological expertise in secret. Dissatisfied with being on just one island, she then pursued a plan to destroy two neighboring islands, Bird Island and Piggy Island, with a superweapon that she and her eagles constructed. When she finally completed her weapon and fired it for the first known time on those two islands, she inadvertently ended the Great Egg War between the Birds and Pigs, drawing them into an alliance to stop her before she could wipe them out.
Knowing that such adversary could destroy her weapon before she could upgrade it to inflict maximum destruction, Zeta ensured that her eagles would keep the weapon under guard, armed with ice spears, while urging the scientist eagles, including Glenn to make haste in completing the necessary experiments to enable the superweapon to fire lava-ice balls to destroy both island effectively, punishing those who failed. Most of the guards stayed inside the base to protect the weapon, with only a few eagles stationed to watch for intruders outside her base, who failed to notice the alliance's special forces beginning their mission to destroy the weapon a few days after it was formed. Two eagles, Carl and Jerry were assigned to guard what appeared to be the base's main entrance, but did not anticipate that much of the special forces team disguising themselves as Harvey, a mechanical decoy eagle, to sneak in.
The special forces team controlling Harvey steals a key card from Brad in one of the base's bathrooms, knocking him out with it, to enter the main cannon chamber. The team then distracts all the eagle guards inside with a break dance, until Chuck notices that Hank, one of the toughest Eagles in Zeta's guard squad, have subdued and captured Red and Silver after the former made a prior botched attempt to disable the cannon. Out of desperation, he accidentally destroys the Harvey costume, forcing the special forces to retreat and lock themselves in a room to regroup. The dancing eagles somehow got carried away with the entertainment Harvey offered so that they ended up not noticing the real intruders as they escaped detection.
With no threats in sight at the moment, the eagles returned to duty, until Zeta announced that her cannon was finally ready to launch a barrage of emulsified lava-ice balls for maximum destruction in ten minutes, rallying them to remind them that her vision with them was close at hand. By that time, the Bird-Pig elite forces reunited with Red and Silver just as they freed themselves from captivity and put together a renewed plan to stop Zeta. After Chuck blocks out the base's security cameras, all the eagle guards in the cannon chamber, continuing in their menial guard duties, then notice Bomb and are about to attack him, before he inexplicably offers to party with them at Regal Eagle, a pub at some other part of the island. The eagles foolishly agree to the party, giving Red, Silver and the Pigs an opportunity to attempt to use one of Zeta's ice balls to crush the cannon. The eagles soon return to the cannon floor after Zeta alerts them to Red and Silver's escape from captivity. Watching that plan fail, they then point their weapons at Red and Silver just as the cannon is ready to fire.
Mighty Eagle then arrives in a vain attempt to convince Zeta to abandon her plans, but it gives Silver another idea and a second chance to destroy the cannon by calling on Chuck to tie a strand of her super string across the muzzle, so that it would snag the cannon's missiles and pull them back inside to destroy it, which ultimately succeeds. The eagles quickly escape the ensuing destruction of the base, surviving it all. Zeta then comes to regret her actions and agrees to marry Mighty Eagle at long last, and her eagle allies agree to attend the wedding at the beach of Bird Island.