Avian community structure and habitat use in a Southern New England estuary

Abstract

The habitat use of 126, 566 birds observed in a 158-ha tidal pond/salt marsh complex in southeastern Massachusetts was recorded during 218 fixed-width transect and 241 remote-count censuses conducted year-round over 5 years (June 1985–May 1990). The most abundant bird groups overall were waterfowl, gulls, shorebirds, and songbirds. Overall avian abundunce was greatest in the fall and winter. Avian richness ranged from a mean of 15 species in winter to 26 in summer; 131 species were sighted overall. Waterfowl, shorebirds, and gulls used tidal pond habitats (including flats) to a greater extent than marsh habitats; use of marsh habitats increased with tidal stage for each of those groups. Wading birds were more abundant in marsh habitats than in pond habitats, and songbirds used marsh habitats exclusively. The permanently flooded (subtidal) west pond segment was used to the greatest extent by cormorants and diving ducks and least by shorebirds and wading birds. Tidal stage influenced abundance patterns of shorebirds and gulls and activity patterns of shorebirds, gulls, and waterfowl. Time of day influenced abundance patterns of gulls. All macrohabitat types (intertidal and subtidal pond, emergent marsh) were used to a substantial degree by multiple bird groups indicating that the loss or disturbance of any type could negatively affect the estuarine avifauna.