Flamingos are known for their long legs, long necks, and party-pink feathers. Now scientists have discovered, for the first time, that the birds form long-lasting and loyal friendships—and that physical traits may play a role in those bonds.

The enduring partnerships among flamingos include mated couples that build nests together and raise chicks every year, as well as same-sex friends and groups of three to six close buddies.

Six species of flamingo inhabit large saline or alkaline lakes, mudflats, or shallow lagoons around the world, including the Americas, Africa, Europe, and Asia. The highly gregarious birds’ flocks typically number in the thousands.

Study leader Paul Rose, a behavioral ecologist at the University of Exeter in the United Kingdom, wanted to find out