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NATURAL HISTORY

MACGILLIVRAY’S SEASIDE SPARROW } Ammodramus maritimus macgillivraii
FAMILY: Fringillidae

DESCRIPTION: The MacGillivray’s seaside sparrow is a small bird, measuring about 5 inches in length. It has a dark, gray back; a short, olive-brown tail and wings; light-gray streaks on its breast and sides; yellow lores; and gray ear patches behind its eyes. There is a small patch of yellow  on the edge of each of its wings. Male and female plumage looks similar.

HABITAT: This sparrow inhabits interior northern Florida’s coastal marshes dominated by smooth cordgrass interspersed with stands of black needlerush. The sparrow favors saltwater marshes for about half of the year but moves to marshes that are flooded with fresh to slightly brackish water for breeding and nesting.

RANGE: The MacGillivray’s seaside sparrow’s original range probably included all suitable habitats in coastal eastern and southeastern Florida, extending to northern North Carolina. Currently the known distribution of the bird is restricted to coastal marshes north of the St. John’s River to northern North Carolina.

MIGRATION: This bird is nonmigratory.

BREEDING: Nesting occurs from spring through early summer with the time and length of the nesting period dependent on flooding — nesting activities decrease abruptly when marshes flood. MacGillivray’s seaside sparrows spend the fall and winter in high-salinity marshes near coastal islands, but move inshore to freshwater or brackish marshes for the nesting season. The birds construct cupped nests in clumps of grass about 6 inches above the ground. Usually 2 to 5 eggs are laid. The female incubates the eggs for two weeks, and young fledge at approximately 10 days old. When the young birds can fly, the sparrows return to saltier marshes

LIFE CYCLE: Sparrows are generally short-lived, with an average lifespan of two to three years.

FEEDING: MacGillivray’s seaside sparrows are omnivorous but have a special taste for tiny marsh crabs and crustaceans. They will also eat insects and seeds found in the marshes they inhabit.

THREATS: The principal threats to the MacGillivray’s seaside sparrow are sea-level rise and increased storm surge — both byproducts of anthropogenic climate change. Rising sea levels will eliminate critical nesting and foraging habitat for the MacGillivray’s seaside sparrow, while strong storm surges into the sparrow’s marsh habitat can destroy nesting areas. Sea levels along Florida coasts are expected to rise between 3 and 9 feet this century. Climate change related threats to the MacGillivray’s seaside sparrow are compounded by fragmentation of their wetlands habitat by development, as well as by habitat degradation through sedimentation, dam operations, pollution and unsustainable water-use practices.

POPULATION TREND: The MacGillivray’s seaside sparrow population is decreasing.

Seaside sparrow image courrtesy Flickr/Jeff & Amy