The term 'long-legged marsh bird' can be summarized by two crossword solutions: stilt (5 letters) and EGRET (5 letters). Stilts are a type of wading bird with long, thin legs and a long neck. They are found in wetlands around the world, including marshes. Egrets are also a type of wading bird with long legs and a long neck. They are found in wetlands, marshes, and other wetland habitats. Both stilts and egrets have white plumage and are often seen standing in shallow water.