The Cape Sable seaside sparrow is the only bird restricted
entirely to the Everglades ecosystem. The 5-inch-long sparrow is
dark olive-gray and brown on the back and light gray with dark
olive streaks on the sides. It has small patches of yellow feathers
in front of the eyes and at the bend of the wings. Because of their
small size, drab appearance, and secretive habits, seaside sparrows
usually are heard before they are seen. The male's song consists of
a few introductory notes followed by a "buzzy" trill.