Cape Sable Seaside Sparrow: Ammodramus maritimus mirabilis
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.
The non-migratory Cape Sable seaside sparrow occurs almost
exclusively in Everglades National Park and Big Cypress National
Preserve in Dade and Monroe counties. Seaside sparrows are normally
found along the coast, however, this subspecies occupies seasonally
flooded inland prairies of muhly grass, short sawgrass, and
cordgrass. Areas of dense cordgrass, cattail, and shrubs are
avoided. The sparrow has not been found on Cape Sable since the
1970s due to habitat changes.
The Cape Sable seaside sparrow is adapted to a life in
vegetation that is periodically burned and flooded. Fires and
flooding maintain suitable habitat by preventing the invasion of
shrubs and trees. However, fires and high water levels during the
nesting season can threaten eggs and recently fledged young. The
Cape Sable seaside sparrow is sometimes called the "Goldilocks
bird" because conditions have to be just right for its
Cape Sable seaside sparrows are dietary generalists, taking
advantage of any food available as they forage low in the grass and
on the ground. They feed on grasshoppers, caterpillars, beetles,
spiders, and grass and sedge seeds. Adults remove the legs and
wings from insects before feeding them to their young.
Nesting can occur from February through August with most
occurring during April and May. The time and length of the nesting
season depends on flooding. Nesting will be delayed or ended if
water levels are too high. Males sing from the tops of grass stems
early in the morning during the nesting season. Nests are
constructed in clumps of grass about 6 inches above the ground.
Usually 3-4 eggs are laid. The female incubates the eggs for 12
days and young fledge at 9-11 days old. Two or three nests are
attempted each season with a success rate of 40-75%. The sparrow's
high reproductive potential help it persist in a variable
Some nests are lost to flooding and fires. Raccoons, snakes,
rice rats and hawks are probably predators of Cape Sable seaside
sparrows. Predation by a cottonmouth has been documented.
The Cape Sable seaside sparrow was classified as endangered by
the U.S. Fish and Wildlife Service and the Florida Fish and
Wildlife Conservation Commission because of its low numbers,
limited distribution, and threats to its habitat. Areas of critical
habitat were designated for the sparrow. There were an estimated
6,656 Cape Sable seaside sparrows in 1981, but annual surveys since
1992 indicate a decline to an estimated 2,624 birds by 2002.
Habitat is maintained by prescribed fire, and water levels are
regulated to benefit the sparrow. However, water management in the
Everglades has been controversial because of possible negative
impacts on other endangered species and human land uses.