BARRIER BAY ISLANDS: Background

Barrier islands are very widespread throughout the mid-Atlantic region protecting nearly the entire coastal shoreline. Barriers within the region vary from 4 to 40 km in length, range from less than 1 km to 5 km in width and are separated from the mainland by lagoons and bays up to 48 km wide. Barrier islands along the Atlantic Coast are highly dynamic mosaics composed of beaches, dunes, shrublands, maritime forests and marshes. The primary agents of change within the barriers are succession that generates habitats from dunes to forests and winter storms that

set back succession by disturbing islands and creating open habitats. Avian species that inhabit these islands exist within specific disturbance/successional niches that depend on both of these processes.

Due to their natural beauty, barrier islands have always been sought out by the human population for recreation and development. Between 1945 and 1975, 3,286 ha of barrier island habitat was lost to development within the planning unit. By 1975, developed land represented 21.2% of the total land area within the island chain. Due to proximity to urban centers, most of this development has occurred within the northern reaches of the planning unit. A total of 47.4% of the island area in New Jersey is developed compared to 29.2%, 13.7% and only 1.2% for Delaware, Maryland, and Virginia respectively. Since the mid-1970's development rates have been greatly reduced within the physiographic region. Virtually all of the remaining undeveloped barriers are owned by the U.S. Fish and Wildlife Service, U.S. Park Service, respective state governments, or nonprofit conservation organizations. Maryland and Virginia currently contain one of the most pristine barrier island chains remaining along the Atlantic Coast.

In addition to the barrier islands, the region contains a large number of islands that occur within the lagoons behind barriers or within the Chesapeake and Delaware Bays and their tributaries. These islands vary considerably in size and structure from sand and shell bars to marshlands to complex uplands. Although a number of these islands have been formed by natural processes, the majority have likely been formed by deposition of spoil material from dredging operations or through other anthropogenic activities. The total collective area contained within bay islands is not currently known and likely changes on an annual basis due to the dynamics of the small depositional islands. However, many well-known sites within the region have been greatly reduced in size or have disappeared entirely in recent years due to erosion.

Barrier and bay islands support a significant component of the regional avifauna. More than 20 species either breed exclusively on these islands or reach their highest densities there. Collectively, these islands support more than 90% of the colonial waterbirds within the region and a higher percentage of the non-colonial beach-nesting species.