Atlantic Puffins are very social birds. They nest in colonies, where several pairs have nests close together. The puffins interact regularly through many behaviors, including a courthsip display called billing. When Project Puffin began to bring Atlantic Puffins back to Eastern Egg Rock, the researchers thought the puffins might not stay if they returned to an island with no other puffins. To simulate puffins and make returning birds feel more at home, we used decoys of puffins. When the first puffins returned, they actually went over to the decoys and "billed with them."

In mating and courtship the puffins will pair up before they come onto the island from the ocean. Once they are on land, the pair may perform billing, a behavior where puffins rub their beaks together. This display usually will draw a crowd of puffins to share in the excitement.

An aggressive encounter between two puffins often begins by gaping. This involves a puffin puffing up their body to look bigger and opening their wings and beak slightly. The wider the beak is opened the more upset the puffin. The puffin may also stomp its foot in place to show its displeasure. The bright colors of the feet and beak help illustrate these motions.

If the aggressive encounter escalates into a full-scale brawl the puffins will lock beaks. They will then attempt to topple each other in a wrestling match by using their feet and wings in a flurry of action. A fight may gather a crowd of 10 or more puffin spectators. The combatants may become so involved in the fight they end up rolling off their rocky perch.