The term 'Small Seabird' can be broken down into two crossword solutions: PETREL (6 letters) and TERN (4 letters). Petrels are seabirds in the family Procellariidae, which includes shearwaters, fulmars, and prions. They are typically found in the open ocean and breed on remote islands. Terns are a group of seabirds in the family Laridae, which also includes gulls and skimmers. They are usually found near coasts and breed on coastal islands or inland. Both petrels and terns are small seabirds that are adapted to life at sea.