Southern Bight, Minas Basin (NS020)

Southern Bight, Minas Basin (NS020)

Bay of Fundy (near Wolfville), Nova Scotia

Site Description

The Southern Bight of the Minas Basin, which includes the Avon River situated about 12 km north of Wolfville, is a large embayment in the Minas Basin, Bay of Fundy, south of the boundary line between Medford and Bramber. The Southern Bight is a large tidal embayment, chiefly composed of intertidal mudflats that are divided by river channels into five sections, varying in substrate (sand/silt gradients) and invertebrate fauna. These five sections include Kingsport-Medford, Porters Point, Starrs Point, Evangeline Beach, and Avonport.

Birds

The mud flats at the head of the Bay of Fundy are important staging grounds for an estimated 1 to 2 million shorebirds in late July and early August (in this and other adjacent IBAs). At low tide, vast areas of mud and sand flats, and salt marshes are exposed - the result of the Bay of Fundys tides, which are the highest tides in the world (up to 16 m). The rich red-brown mud harbors millions of Fundy mud shrimp, a vital food source for the Semipalmated Sandpiper. The Southern Bight, Minas Basin and other regions in the Bay of Fundy are the last and most important stopovers for the sandpipers, where they build up fat stores enabling them to make the long southward migration to South America in three to four days. The availability of such a prodigious food supply attracts 50 to 95% of the worlds Semipalmated Sandpipers, along with many other species of shorebirds, to the Bay of Fundy.

Some of these birds are found in the Southern Bight, Minas Basin: 51,667 Semipalmated Sandpipers have been recorded in late July and early August. This figure accounts for 1.4% of the global population. Also, more than 1% of the North American Black-bellied Plover population has been observed at this site. This number is based on data from 1974 to 1983 using an improved estimation method that was reported in Canadian Field Naturalist in 1993.

A high diversity of other migrant shorebirds forage on the large intertidal mud and sand flats throughout the Bight. Commonly observed species include: Red Knot, Sanderling, Short-billed Dowitcher, Least Sandpiper, and Semipalmated Plover. Some of these species may at times occur in numbers exceeding 1% of their North American or global populations, but surveys often do not cover all parts of the basin. Likewise, it is believed that an accurate census of the entire basin would reveal greater than 100,00 shorebirds.

During the spring tides, some of the sandpipers use nearby dyked fields for roosting.

Conservation Issues

The Minas Basin area was declared a Hemispheric Shorebird Reserve, under the Western Hemisphere Shorebird Reserve Network (WHSRN) in 1988. The Minas Basin was also separately designated as Ramsar site; Wetlands of International Importance, in the 1980s. In recent years, a commercial harvest of rag-worms, for bait, has disrupted the intertidal invertebrate community and thus staging shorebirds.

Several university thesis studies have been conducted here since the early 1970s, and there are some ongoing surveys, but the most extensive monitoring occurred in 1976 and 1997.

IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status

• Semipalmated Sandpiper300,000 (max.)
• Semipalmated Plover5,000 (max.)
• Short-billed Dowitcher1,613 (max.)
• Herring Gull30,610 (max.)
• Great Black-backed Gull5,736 (max.)
• Black-bellied Plover2,130 (max.)
• Chimney Swift1,094 (max.)
• Savannah Sparrow100 (max.)
• Piping Plover7 (max.)
• American Black Duck4,696 (max.)