The term 'IBIS's Cousin' refers to three species of birds that are related to the IBIS. These species are the EGRET (5 letters), HERON (5 letters), and Spoonbill (9 letters). The EGRET is a white bird with long legs and a long neck, while the HERON is a large wading bird with a long neck and long legs. The Spoonbill is a large wading bird with a spoon-shaped bill. All three species are found in wetlands and coastal areas around the world.