To kill Manny and his friends.
To pillage, plunder, rifle, and loot without giving a hoot (both failed).
The Pirates are the central antagonists of the 2012 animated film Ice Age: Continental Drift.
Their leader is Captain Gutt, the main antagonist of the film, and they plunder incoming ice caps for new parts for their ship and raiding all food supplies from other animals, ruling the seas without no-one stopping them until encountering their archenemies, the Sub-Zero Heroes (Manny, Diego and Sid).
It is hinted that Captain Gutt first came to this idea after his kind was going extinct and he also need allies for survival.
They all were going extinct and doomed to die in this changing world, except Flynn the Elephant Seal and Silas the Blue-Footed Booby. Each found across the world by Captain Gutt and serve him as his friends.
Shira, Silas, Gupta and Flynn are the meat eaters of the pirates.
Shira is the second character to betray a group and leader, Diego is the first with the Soto and the Sabertooth Tiger pack.
Shira and Squint may be the only ones in the group who are still alive. Flynn is also most likely still alive (since he is a sea creature). Silas, too, could have survived, since the birds of his species are able to come out of the water after they drop into it to catch fishes, so he could have surfaced and flown away after Precious blasted him in the sea.